Adventures with a Pocket Binocular Part II.

A work commenced November 11, Anno Domini 2019.

Part II

Subject to Copyright. Completed text will cite references & bibliography .

 

 

 

Taming a Flame:

Caveman’s telly.

The second week of February 2020 brought cold and tempestuous weather to Britain, with the arrival of Storm Ciara. Just as we were preparing our family evening meal on Sunday February 9, the storm caused a power cut which left us and our fellow villagers without electricity for a few hours. So out came the candles and on went the coal fire to keep us out of total darkness and comfortably warm. I have always been somewhat in awe of fire and fetched my pocket glass to observe the cadence of its flames as they rose upwards into the chimney column. Because of their excellent close focus, my pocket glasses can entertain me as much indoors as they can out of doors!

As I drank up the wondrous display of light and colour of the coal fire from the comfort of my couch just a few metres away, my mind reflected on the importance of fire to the progress of humanity over the milennia. Nature not only produced the fuels but also the reactive gas(oxygen) needed for fires to occur. They are thus vital components of a life-bearing planet. With an atmosphere of 21 per cent oxygen, it is just right to allow fuels(reduced carbon substrates) to ignite and generate heat and light. If the percentage of oxygen in our atmopshere were only a little higher, spontaneous combustion would be much more common and many areas of the world would experience the devastating effects recently suffered by the people and biota of Australia. If the oxygen levels were lower, we would be unable to extract enough chemical energy from food to allow us to do much in the way of higher cognitive activities such as talking, calculating and praying.

The unique ability of humans to create and control fire is probably the single most important activity that launched the high technology societies in which we now live. In its basic form, it provided our hunter-gatherer ancestors with warmth and light on cold winter nights, which allowed us to work for longer and so boosting human productivity. Its intense heat protected us from hungry predators stalking us out in the dead of night. By cooking food, it killed germs that might have made us sick. The intense heat of the fire also helped break down hard-to-digest foods, enabling us to extract their nutrients more effectively. With fire, humans could greatly expand the varieties of territories we could eke out a living in. No longer were mountains and frozen northern wastelands verboten. Fire must have triggered the largest exodus of humans from the warm grasslands of East Africa/Middle East, where we probably first emerged from after our forced expulsion from the Garden of Eden.

Our innate capacity to experiment led to further discoveries allied to fire. We learned to ‘cook’ wood, yielding the amazing substance we now call charcoal, and with that we could generate temperatures far in excess of any normal fire(up to a 1000C in fact!). Charcoal is a wonderful reducing agent, empowering our distant ancestors with the ability to ‘pull’ metals from ores; copper, tin, lead and the creation of alloys like bronze. Once we understood how to use air to increase the temperature of furnaces, the extraction of iron finally became possible. The age of metallurgy was born and with it the great transformation of our lives. Without a knowledge of combustion, we would have no ceramics, no cars, buses or trains, no computers, iphones or tablets; no skyrockets to scale heaven.

And no glass to peer through!

My binoculars would not exist were it not for fire!

And yet there are still deeper things to ponder. Why, for instance, doesn’t the coal I fetch from our bunker not react with the oxygen that surrounds it? Why, as creatures who ‘slow burn’ our food, do we not burst into flames? The answer is not all obvious, but pertains to the stability of both oxygen and coal at ordinary terrestrial temperatures. To burn coal, I must elevate its energy enough to initate the reaction, that is, by igniting the coal with a spark. And deep inside the countless trillions of cells that comprise the human body, enzymes(biological catalysts) lower the activation energy enough for our reduced foodstuffs to react with the molecular oxygen delivered to our body cells via myriad haemoglobin molecules.

But our ability to tame a flame is also related to our physical size. Think on it: if we were as small as a mouse say, we would be unable to get close enough to a fire to keep it fuelled without getting seriously injured. We’d also lack the muscle power to bring enough fuel in the form of chopped wood or dry brush to sustain the same fire. But humans are large enough(1.5 to 2m), and endowed with long enough arms with an ingenious manipulative tool at their ends(fingers with an opposable thumb), and with muscles powerful enough to chop and carry wood and lay it on a fire with outstreched arms, so keeping a safe distance from its desctructive flames.

And if we were significantly larger, gravitational forces would put much higher strains on our limbs. Carrying anything would much more difficult. Biophysicists have long known that simple power laws govern how body weight and limb strength scale with increasing height. Weight scales as the cube of height, but limb strength only scales with the square of height. That means that if we were much taller, strenuous physical activities would become far more challenging and even downright dangerous. Our limbs would shatter under their own weight and fumbling Prometheus falling into a fire would be a distinct possibility. The same principles explain why, upon faltering in a similar situation, a little child would emerge unscathed.

Can our physical size and the chemical and physical properties of our atmosphere that allow fires to be tamed and pressed into service by our kind be just coincidence? Is this just another serendipitous chain of events that happened to occur on our planet? Most certainly not! The godless naturalists can provide no credible answers to these questions.

They are, quite literally, left in the dark!

On the otherhand, a Creator God – an Unquenchable Fire – who designed this world for His human imagers to transform its natural resources seems far more probable to my mind.

Come, let us bow down in worship,
let us kneel before the Lord our Maker;
for he is our God and we are the people of his pasture,
the flock under his care.

Psalm 95:6-7

A Worthy Upgrade

The Leica Trinovid BCA 8 x 20 pocket binocular package.

During the first two weeks of January 2020, I had the opportunity to test drive a Leica Trinovid BCA 8 x 20 pocket glass kindly lent to me by a fellow villager. You can read about my opinions of that instrument here. As that report shows, I was very impressed with its wonderful optical and mechanical quality, but still a little concerned about how much use I would realsitically get out of a glass with very small, 20mm objective lenses. After some cogitation and deliberation, I decided that having two 8 x 25 units(the Opticron Aspheric LE WP and the Zeiss Terra ED) could not be justified, and so I gifted my Opticron to my next-door neighbour and invested in what is arguably one the highest quality achromatic(read non-ED) pocket glasses money can buy. Conducting some price comparisons across the internet, I managed to track down a UK-based seller offering the Trinovid for a very good price and I pulled the trigger.

The package arrived in perfect nick. What I received(see photo above) was a small box (actually double-boxed) with the Leica binocular safely packed inside a soft but rather oversized carry case, a small neckstrap, a comprehensive user manual, a test certificate and a booklet containing details of its 10-year warranty. The binocular had no eyepiece or objective lens caps though, and not even so much as a lens cloth thrown in for good measure!

My neighbour was thrilled to bits to accept the Opticron – a high quality pocket glass  – but I was equally thrilled to finally own arguably one the smallest, useful pocket glasses in existence. And, as my subsequent tests showed, the little Leica proved to be every bit as good as the unit I tested a few short weeks ago.

The little 8 x 20 Leica passed my flashflight tests with flying colours; it was just as clean and devoid of internal reflections as the earlier unit I investigated and delivered pin sharp images rich in contrast almost from edge to edge. There is no question that the quality control on these high-end pocket glasses is remarkably consistent. Optically, the Leica Trinovid BCA 8 x 20 is unquestionably a step up from the Opticron in terms of sharpness and contrast. Indeed, it is right up there with the Zeiss Terra 8 x 25, but in smaller, more elegant frame.

Once I had done my testing, I registered the instrument on Leica’s sports optics website(the serial number being printed under the right eyecup).

The Leica Trinovid BCA 8 x 20(left) has a smaller frame to the Zeiss Terra ED 8 x 25 (right).

As much of my work on telescopes over the last decade has involved raising amateur awareness of the wonderful properties of well-made achromatic refractors, I was thrilled to see that a top company like Leica was creating state-of-the-art miniature binoculars using traditional crown and flint glass. It showed me once and for all that excellent binocular optics doesn’t necessarily require the use of low dispersion lenses. Rather, it’s more to do with the precise figuring of the glass, as well as the application of state-of-the-art coatings to all optical surfaces that delivers this degree of excellence.

Both the Zeiss and the Leica are endowed with similar, high-quality optics, but one has ED Schott glass (the Zeiss) comprising one or more of its objective elements, while the Leica does not. But if I were to make an aperture stop for the Zeiss, reducing its effective aperture to 20mm, I would in effect have two instruments operating at 8 x 20 and with the same exit pupil(2.5mm). So the biggest difference between them would be the ED component and that would allow me to investigate claims made by a number of individuals over the years; specifically in relation to the brightness of the images served up by ED and non-ED optics. Is there any or much truth in this claim?

So I set to work performing some experiments in low light conditions, carefully comparing the images served up by both pocket glasses. I hope to report back on this in a later post.

A Better Case for a New Pocket Glass

The Leica binocular came with a soft padded case that was too large to fit it well. As you can see from the image below, the binocular has quite a bit of wiggle room inside the case and even when it’s closed, dust can easily enter and accumulate over time. This is especially the case as the instrument was not supplied with endcaps to cover the ocular and objective lenses.

The Leica logoed soft carry case is too large to fit the little Leica 8 x 20 and is not a very good deterrant against dust when the binocular has no dust caps.

I felt that there must be a better solution to this storage problem. So, after taking into account the dimensions of the Leica glass, I searched online for a suitable replacement. Eventually, I came across a tiny clamshell case, similar to the one I received with the Zeiss Terra but smaller again. Here is what it looks like:

A tiny, anti-shock clamshell case that zips shut.

Here is another photo of the clamshell case compared with the original case for reference:

The Clamshell case is significantly smaller than the supplied Leica soft padded case.

Costing just £6.99 inclusive of delivery, the clamshell case is shockproof and can be zip-closed.

The clamshell opens up revealing the storage space inside. Note the sachet of silica gel.

To my relief the Leica binocular fitted the hard clamshell case perfectly and can even accommodate the binocular with the eyecups kept up for quicker deployment.

The fully folded Leica 8x 20 sitting inside the new case.

The case also allows the Leica binocular to be stored with the eyepieces fully extended upward for quicker deployment.

I was delighted with the new case as it affords far better protection of the optics and is even easier to store away owing to its very small dimensions. The image below shows its size in comparison to the Zeiss Terra case.

Two good clamshells for two fine pocket glasses.

This should serve as an excellent storage case for the Leica pocket glass, protecting it from dust and moisture; an important issue since the instrument is splashproof but not waterproof.

Maybe I should contact Leica Sports Optics with this suggestion?

A Triumph for Aperture & Ergonomics!

Pure sweet!

Both the Leica Trinovid BCA 8 x 20 and the Zeiss Terra ED 8 x 25 are top-notch optical performers. But while the Leica is significantly more expensive than the Zeiss, it is the latter instrument that will prove to be the more versatile. Let’s compare some of the specifications to see why this is the case.

The Zeiss has a larger aperture and bigger exit pupil, making it significantly more effective in low light conditions and for observing the night sky.  The larger exit pupil (3.125mm) also makes it considerably easier to line up your eye pupils rendering the views more immersive and comfortable. The Zeiss has a much larger focus wheel making it the easy choice in cold weather where gloves are worn. In addition, the Zeiss Terra is more pleasant to hold in cold weather since the thermal conduction of its polymer frame is much lower than the aluminium frame of the Leica, which always feels very cold to touch in cold winter conditions.

The Zeiss has better eye relief than the Leica(16mm and 14mm, respectively) making it easier for eye glass wearers to engage with the entire field of view.  What is more, the Zeiss Terra has a considerably larger frame than the Leica pocket glass rendering it much more stable to hold steady during prolonged field use. It also has a noticeably wider field of view than the Leica(6.8 degrees as opposed to 6.3 degrees). And while the build quality is definitely better in the little Leica pocket glass, the Zeiss is really not that far behind it.

I like to think that the ethos behind the design of the Zeiss Terra pocket glass is different to that of the Leica. The frame of the Zeiss is constructed from modern, strong but lightweight materials (fibreglass-reinforced polyamide). Indeed, it only weighs about 75 grams more than the Leica glass. In addition, the Zeiss is fully fogproof and waterproof, whilst the Leica is merely splashproof and so the former has a distinct edge over the latter when moving from cold, damp conditions to a wam, interior environment. One other issue is worth mentioning; the Leica Trinovid BCA is much more fiddly to deploy than the Zeiss. Have you ever tried getting your optimal interpupillary distance with the Leica when attempting to view the night sky in the dark? It can be downright frustrating to say the least! Not so with the Zeiss Terra!

Seen in this light, it’s relatively easy to see why the Zeiss would be my first choice for standard field use. It just ticks so many more boxes than the Leica. Instead of feeling slightly anxious about using a small, ornate pocket glass, that anxiety all but disappears while using the Zeiss. That said, I can see where the Leica might be better suited than the Zeiss. Because the Leica is smaller and has less garish external colours than the Zeiss, it would probably be suited that little bit better to watching sports events from a distance or during an evening at the theatre. Its superior control of glare, internal reflections and less intense diffraction spikes when looking at bright artificial light sources also makes it eminently qualified for observing urban nightscapes and the occasional bout of ‘take anywhere’ tomfoolery.

All of this resonates well with experiences I have had when comparing smaller grab ‘n’ go refractors to my upgraded 130mm Newtonian reflector. Despite being less expensive than the refractors, the larger Newtonian proved the better choice time and time again, showing that you don’t always get what you pay for! Just like the Zeiss Terra, the 130mm Newtonian simply represents more bang for your buck!

Does ED glass in a binocular result in brighter images?

Anyone who has followed my blogs over the years will know that I am sceptical of the claims made by fanatics of ED glass. I found much of their claims somewhat pretentious, including statements like, ” Apos resolve binary stars better than traditional achromats and Newtonian reflectors.” My own tests conducted both in the field and backed up by numerous historical references showed otherwise, which is one of the reasons I got rid of a whole raft of refractors with ED glass and replaced them with much more economical and powerful Newtonian reflectors. It’s relatively easy to find comments about small, low- power ED binoculars where the following claim is  often made, “Binoculars containing ED glass give brighter images than those using traditional traditional crown and flint glass.”

Now, I can certainly see why binocular objectives containing ED glass might focus the visible wavelengths of light they collect that little bit more tightly than those without such elements, which might give them an edge in terms of producing a slightly brighter image, but not so much to make the difference ‘obvious’ or ‘immediately apparent.’ What I did discover is that it is often the quality of coatings applied to the lenses and prisms that result in noticeable differences in image brightness, since more efficient coatings result in a greater light transmission to the eyes. My curiosity was further piqued when I came across this short youtube review, where the presenter noted that a binocular with so-called ‘HD coatings'(read dielectric) produced a much more dramatic effect on image brightness than ED glass-containing instruments with the same specifications utilising non-dielectric(lower reflectivity) coatings.

So I wanted to test the claim that ED glass containing binoculars result in brighter images by conducting a series of observations using three binoculars; my Zeiss Terra ED 8 x 25(containing Schott ED glass and retailing for £270), my Leica Trinovid BCA 8 x 20(bought for £319) and my Celestron Trailseeker 8x 32 binocular(a £126 purchase). The latter instruments have high quality coatings but do not include ED glass containing objectives. The Celestron Trailseeker, in particular, has dielectric coatings applied to the roof prisms, creating the same ‘HD images’ to the Hawke Frontier X 8 x 32 model featured in the youtube clip linked to above. Surprisingly, Leica do not appear to publish details of the coatings they apply to their optical components and no data on its light transmission. The Zeiss Terra ED has a published light transmission of 88 per cent, which you can find on the Zeiss sports optics website.

The stopped down Zeiss Terra ED, effectively working as an 8 x 20 unit.

In order to make the comparison as fair as possible, I made a 20mm aperture stop for the Terra, cutting its effective aperture from 25mm to 20mm but still retaining a magnification of 8x. I then compared the performance of this stopped down binocular to the Leica 8 x 20 (at full aperture) under low light conditions at dusk, when the light was rapidly fading in the evening. I conducted such tests on three separate occasions and, in each case, I elicited the opinions of a number of other individuals, my wife and a few of my students, to ensure that the results were consistent with my own. The target was a tree branch located about 50 yards in the distance. Consensus was reached. The stopped down Terra ED yielded a very slightly brighter image than the Leica 8 x 20.

The stopped down Celestron Trailseeker 8 x 32 working at an effective aperture of 25mm.

But then I set up a similar set of experiments comparing a stopped down Celestron Trailseeker 8 x 32 with an effective aperture of 25mm with the Zeiss Terra ED 8 x 25 at full aperture(so also at 25mm). As with the first experiment, I canvassed the opinions of a couple of my students and my wife on the same target and under late, dusky lighting conditions. The results were very surprising! 3 out of four of us(including yours truly) reported the Celestron to have an edge in brightness over the Zeiss, while a fourth observer reported essentially equal brightnesses in both the stopped down Celestron and the Zeiss at full aperture.

Conclusions: The presence of ED glass did not result in any dramatic increases in brightness in both tests and when compared against the non-ED Celestron, the results seemed to indicate that it had, in fact, a slight edge over the ED containing Zeiss Terra. This further suggested that the Celestron Trailseeker had a light transmission of at least 88 per cent (and possibly a little bit higher), indicating that (as I suspected from other tests) it is indeed a highly efficient light gathering instrument. The results for the Leica Trinovid might also suggest that it may actually have a slightly lower transmission than the Zeiss(88 per cent), although I was unable to verify this in practice owing to the lack of published data on this Leica binocular.

I would warmly encourage other binocular enthusiasts to conduct similar experiments if they have the means. 

These experiments deepen my conviction that the marketing of ED glass in small, low-power binoculars like these, is yet another clever ploy to lure unsuspecting consumers to choose ED-containing binoculars over their non-ED counterparts based on misleading, if not false, claims. Don’t be a gullible gayponaut; never buy a binocular based solely on the presence or absence of low dispersion (ED glass). Check out the other specifications that an instrument offers before parting with your hard earned cash, or try before you buy.

A Vibrant Star Cluster in Coma Berenices

On the Lion’s back; Melotte 111 in Coma Berenices, as seen on page 125 of our guide book.

February has proven to be a very unsettled month weatherwise. The UK has endured not one, but two big storms; Ciara and Denis, causing widespread flooding and general havoc with many communities across the country. But even amidst this grotty weather, the night sky still presents opportunities to observe it, if only for a few minutes at a time. And small binoculars are the ideal instrument to use in these very unsettled conditions, as they require no set up time. If a clear spell presents itself, I’m away out to have a gander.

By mid-February, the constellation of Leo approaches the meridian around local midnight; a sure sign that Spring is on the way. And over in the east, other signs of vernality present themselves, particularly brilliant orange Arcturus, which has cleared the murky horizon and is rising ever higher in the sky, together with the many interesting stars that collectively inhabit the constellation of Bootes. Looking over to the northeast, the bright summer star, Vega, is reassertting itself, while setting in the west, Orion and Taurus are now past their glory days.

This time of year, I like to visit a conspicuous patch of sky just east of the hind legs of the celestial Lion. Easy to pick up in the pocket glass, the famous Coma Cluster( Melotte 111) is no trouble to track down in a dark, moonless sky as a smattering of 4th and 5th magnitude stars concentrated into an area spanning some 5 degrees. Light pollution in towns and cities often drowns out even its brightest members, but from a dark country sky, the Coma Cluster is a fine naked eye sight, with at least half a dozen members being clearly visible to my unaided eyes. But the view greatly grows in majesty when examined with a small binocular. The 8 x 25 Terra frames the cluster very well, where the characteristic ‘V’ shaped stellar configuration makes it child’s play to identify. Several dozen suns are easily discerned in this cluster in a pocket glass and up to 80 members can be pulled out of the dark with larger glasses.

Our guidebook on page 124 informs us that the centre of the cluster is estimated to be about 285 light years away, with its many main sequence stars estimated to have an age of approximately half a billion years. Such a vast amount of time is more than sufficient to prize its stars apart, which goes a long way to explaining why the cluster is so large and sprawling as seen in the pocket glass.  I made a sketch of the Coma Cluster last season using a larger binocular, which is reproduced below for interest.

Insights from an Old Book

Leafing through an old book can reveal  some surprising insights.

My two pocket glasses serve up breathtaking images of the creation. In terms of absolute optical quality, millimetre for millimetre, I would give the edge to the Leica 8 x 20. Yet, in comparing and constrasting it to the Zeiss Terra, I have noted a couple of other ways in which the latter instrument pulls ahead of the smaller glass. The first thing is close focus distance; the Zeiss pocket binocular can focus on objects as close as 1.4m away, while the Leica fares considerable worse in this regard, at about 1.8m. This will likely prove important going forward, as I am fond of observing insects, rock formations, colourful mushrooms and other fungi, as well as flowers at very close range. The Zeiss’ wider field of view will also make those close up views more compelling.

The second thing I have noticed is that, with the exception of strongly illuminated(read sunny) daylight scenes, the Zeiss pocket glass serves up noticeably brighter images. And this is true whether fooling around indoors, glassing out of doors on overcast days and in shaded areas like woods and glades. That the Zeiss was producing brighter images under a wide range of conditions surprised me a little until I happened to pick up an old book from my library, written by the late Leif J. Robinson, former editor of Sky & Telescope Magazine, entitled Outdoor Optics. On page 15 of that text, there is a graph(shown below) of pupil diameter versus age for dark-adapted eyes, as well as how the exit pupil behaves under so-called ‘office illumination.’

Exit pupil size versus age for dark-adapted eyes and under office illunination. Source; Outdoor Optics (1990), by Leif J. Robinson.

The ambient brightness (luminance) is measured in units called Lux, where 1 Lux is 1 lumen per square metre. In this wikilink, it gives the luminance values for various illuminated conditions, including office lighting, which can be anywhere from 300 to 500 Lux. Heavily overcast days can have Lux values as low as 100 though, while observing under the canopy of trees in wooded environments might be expected to be even lower. Looking at the size of the exit pupil under office illumination for my age(51) gives a value of ~3.5mm. Although the particular details of how my own pupil behaves is still unknown to me, these results go some way to explaining why the Zeiss Terra(with an exit pupil of 3.13mm) pulls ahead of the Leica (with a smaller exit puipl of 2.5mm)under these conditions. And gathering more light means that I can discern finer details in many dull or dimly lit scenes of extended objects using the larger 8 x 25 glass.

I intend to investigate this phenomenon further by taking measurements of the luminance under differing lighting conditions and relating this to what my eyes discern using these small pocket glasses. Accordingly, I have ordered up a luminance meter to perform these experiments, and will report back on this matter at a later date.

A New Colour Variant of the Zeiss Terra Pocket Now Available!

Remember how I described the Zeiss Terra 8 x 25 as having rather garish colours that might attract unwanted attention from the members of a crowd at sporting events? Well, I just recently discovered that Zeiss are now offering the Terra in not one, but two colour schemes. As well as the black, blue and grey livery on the original Terra, they now offer it in black, white and blue. And here’s what it looks like:

Zeiss Terra ED Pocket 8x25 Binoculars - Black/Black

Maybe someone from Zeiss was reading my blogs lol?

I think it’s rather handsome; don’t you? Source here.

 

To be Continued………………………….

 

De Fideli.

What I’m Reading.

See how the notion of chemical evolution has failed over the decades.

Paperback: £19.09

486 pages.

The origin of life from non-life remains one of the most enduring mysteries of modern science. The Mystery of Life’s Origin: The Continuing Controversy investigates how close scientists are to solving that mystery and explores what we are learning about the origin of life from current research in chemistry, physics, astrobiology, biochemistry, and more. The book includes an updated version of the classic text The Mystery of Life’s Origin by Charles Thaxton, Walter Bradley, and Roger Olsen, and new chapters on the current state of the debate by chemist James Tour, physicist Brian Miller, astronomer Guillermo Gonzalez, biologist Jonathan Wells, and philosopher of science Stephen C. Meyer.

Some Initial Endorsements:

“Cogent, original, compelling.”–Dean Kenyon, Professor Emeritus of Biology, San Francisco State University

“An important contribution to the origin of life field.”–Robert Shapiro, Professor Emeritus of Chemistry, New York University and author of Origins: A Skeptic’s Guide to the Creation of Life on Earth

“A valuable summary of the evidence against the chemical evolution of life… very well thought-out and cleary written.”–Robert Jastrow, founding director of NASA’s Goddard Institute for Space Studies

 

De Fideli.

Spectrum

Take a Closer Look.

 

 

In this blog, I’ll be exploring subjects of general interest/concern to me and wider society in this age of mass deception:

The Dark Side of Transgender Medicine

 

How the Media Manipulates Truth

 

Cogito ergo sum

 

The Secular Case Against Homosexuality

 

Our Fragile Home

 

The Anti-Social Network

 

A Form of Child Abuse

 

Cool stuff you never hear in Church

 

The Rise of Homeschooling

 

James Clerk Maxwell: a Great Life Lived

 

Reasonable Faith: An Interview with Professor Alvin Plantinga

 

Doubting Dodgy Science

 

Evaluating World Views

 

Depraved Minds

 

The Beauty of the Creation

 

The Preciousness of Free Speech

 

Walking your Way to Good Health

 

Did the Eye Really Evolve?

 

Unholy Alliance: when Dodgy Science Merges with Theology

 

The Truth about UFOs

 

The Rise of Neo-Paganism

 

From Spiritual Shipwreck to Salvation

 

The Rise in Euthanasia Killings

 

The Greatest Story Ever Told

 

Holocaust Survivor

 

Coming Soon to a Town Near You: The Rise of Bestiality

 

The Death of Naturalism

 

Anything Goes

 

From Gaypo to Paedo

 

When Scientists Lose the Plot

 

The Sixth Mass Extinction Event in Our Midst

 

‘Depth Charging’ the Values of the Ancient World

 

The Truth about the Fossil Record

 

AI

 

The Language Instinct

 

Not the Same God

 

Greening the Deserts

 

Moving the Herds

 

Evolutionary Atheist gets his Facts Wrong…..Again

 

Distinguished MIT Nuclear Physicist Refutes Scientism

 

Pursuing Truth

 

The Dangers of Yoga

 

Pseudoastronomy

 

Get thee right up thyself! : The New Transhumanist Religion

 

The Biblical Origin of Human Rights and why it’s a Problem for Atheists

 

A Closer Look at the Israeli-Palestinian Conflict

 

Winds of Change: Prestigious Science Journal Concedes Design

 

A Distinguished Chemist Speaks the Truth

 

The Scourge of Pornography

 

Eye

 

Bart Ehrman Debunked

 

An Evil Generation Seeks After a Sign

 

Magnetic Pole Shift

 

Decimation of Global Insect Populations

 

The Spiritual Suicide of a Once Christian Nation

 

Mass Animal Deaths Worldwide

 

Not Going Anywhere

 

UN Report: World’s Food Supply under ‘Severe Threat’ from Loss of Biodiversity

 

False gods of the New Age

 

From Abortion to Infanticide in the “Land of the Free”

 

Sports Personalities Speak Out Over Transgender Athletes

 

Magonus Sucatus Patricius

 

Celebrating a Killing

 

Human “Out of Africa” Theory Debunked

 

The Other Side of the Rainbow

 

Vintage James Tour: How to Cook Up a Proto-Turkey

 

Big Brother Watching

 

Follow the Evidence: The Problem of Orphan Genes

 

Follow the Evidence: The Genius of Birds

 

The Butterfly Enigma

 

Man’s Best Friend

 

Darwinian Evolution On Trial Among Biologists

 

New Fossil Finds Thwart Human Evolutionary Predictions

 

Global Persecution of Christians

 

 Ratio Christi

 

Questions About the Qur’an

 

Engaging with Islam

 

Calling Evil Good

 

Parousia

 

Tall Tales From Yale: Giving up Darwin.

 

More on the Proto-Turkey:  Dr. Tour Responds to Cheap Shots from the Pond Scum Merchants

 

Good Riddance: Despicable British TV Show Axed after Death of Participant

 

There’s Heehaw Out There…ken.

 

The Fastest Growing Insanity the World has Ever Seen

 

Pharmakeia

 

Darwinism & Racism: Natural Bed Fellows

 

The Modern Root of Anti-Semitism

 

Jesus & Archaeology

 

A Victory for Common Sense: Transgender Weightlifter Stripped of his Medals

 

The US Equality Act: A Plea for Caution

 

Reunited: Music & the Human Spirit

 

Gladys Wilson

 

1st Century Christian Insight: The Didache

 

The Clothes Maketh the Man

 

Why Some Books were Left Out of the Bible

 

Why the Human Mind is not Material

 

What God Thinks of Scientific Atheism

 

For the Love of the Creator

 

An Essential Component of a Modern Education

 

Peace Cross

 

Earth: “Presidential Suite” of the Universe

 

How to Really Stand Out in a Crowd

 

Straight from a NASA Scientist: Jewel Planet

 

The Singularity

 

No Life Without Super Intelligence

 

Darwinism as a Cargo Cult

 

Body Plan Development Raises New Headaches for Evolutionists

 

Membrane Biochemistry Stymies Evolutionary Origin of Complex Cells

 

Science Speaks: Common Abortafacients Harmful to Both Mother & Child

 

Biblical Ignoramus Twists the Words of Christ

 

The Multiverse: Just Another Religion

 

Apologia Part I

Part II

Part III

Part IV

Part V

Part VI

 

Attention Parents: American Psycho Association Promoting Polyamory to Pre-Teens as ‘Ethical.’

 

The Only Rainbow God Recognises

 

Calling Time Out on Evolutionists’ Failure to Explain The Cambrian Explosion

 

7 Reasons to Reject Replacement Theology

 

Psychiatric Diagnoses are ‘Scientifically Meaningless’ Study Shows

 

Out of a Far Country: A Gay Son’s Journey to God

 

Universalism Debunked

 

The Prosperity Gospel Debunked

 

New Science Reveals First Cellular Life to be “Amazingly Complex”

 

New Law Firms Being Established to Counter the Rise in Christian Persecution

 

Playing the Numbers 32:23 Game

 

Multiple Lines of Scientific Evidence Converge on 3rd Century BC Age of the Famous Isaiah 53 Scroll.

 

Meet the Gestapo

 

Exposed: Theologians Deceived by Darwinian Ideology

 

New Insights into the Shroud of Turin

 

What we Know and Do Not Know About the Human Genome

 

Debunking Da Vinci Code Tosh

 

Sorry: No Such Thing as “Gay” Penguins

 

Genetic Entropy

 

Dunderheid Alexa

 

The Extinction of Reason

 

A Biblical Perspective on Diet

 

Revelation: Number of Transgender People Seeking Sex Reversals Skyrockets

 

Psychologist Debunks Pseudoscientific Explanations for Human Love & Compassion

 

The Dismantling of the Feminine

 

Disturbing Trends in the Roman Catholic Church

 

N = 402

 

The Nazareth Inscription

 

A Christian Response to Halloween

 

Seeking Methuselah

 

Beware the Enneagram

 

No Safe Spaces!

 

Pale Blue Dot

 

Encyclopedia Galactica

 

Phillip E. Johnson: A Tribute

 

The Darwinian Response to Human Life: Let the Baby Die!

 

The Best Explanation for Beauty

 

What is Feminism?

 

Insects & Light Pollution

 

Candy-Ass Christianity

 

Antiobiotic Resistance in a Post-Darwinian World

 

Adam & Eve: Redux

 

Joyce Meyer

 

Michael Behe Says No to Theistic Evolution

 

New Atheism: An Autopsy

 

Serenading an Old Girl.

 

“Progressive” Christianity as a Political Cult.

 

Israel Folau Vindicated

 

The Church of Satan, Sweden

 

A Rational, Christian Response to Humanism

 

More Depravity: the Sexualisation of Children

 

Shameful Humanity:  Murder of the Unborn Now the Biggest Worldwide Killer.

 

Origin Stories

 

Privileged Planet

 

Brokeness

 

Sorry Sam Smith, You’re Still a ‘He.’

 

Nature Genetics: How ‘Evolutionary Thinking’ led Biologists Astray about Pseudogenes.

 

A Kindgom Divided Against Itself: Why Evolutionary Psychology is Bunk

 

Of Melting Glaciers and Darwinism

 

First US President Addresses 47th March For Life, as theSecular Media Duck for Cover

 

Wolves Among the Sheepfolds

 

The New Science of Separate, Distinct Creations

 

That Sacred Space

 

Faith of the Fatherless

 

More Tales of Darwinian Thuggery

 

Keeping your Children Strong in the Faith

 

Former Editor of Nature Waves Bye Bye to the RNA World

 

At Scientific American: Physicist Pours Cold Water on Scientism

 

A Biblical Perspective on Alcohol Consumption

 

High Priest of a Pseudoscience Rears His Ugly Head Again

 

Another Step into the Human Immorality Sewer: Normalizing Throuples & Sologamy

 

Symptom of a Depraved Society: Scientists Now Fighting to Affirm a Basic Fact of Life: Sex is Binary

 

Speaking the Truth in Love: What the LGBTQ Community Needs to Know

 

The Power of Biblical Prophecy: The Triumphal Entry of Jesus into Jerusalem

8 x 42 vs 8 x 32; Which is More Versatile?

Two good binoculars: The Barr & Stroud Savannah 8 x 42(left) and the Celestron Trailseeker 8 x 32(right).

Many binocular enthusiasts will often recommend a good 8 x 42 as the near perfect all-round instrument for birding, hunting and astronomy. This recommendation seems sensible enough given their medium size, weight and decent light gathering power for use in bright daylight, low light conditions and stargazing. But the increasingly popular compact 8 x 32 has also earned a respectable place in the hearts of many birders and sightseers owing to its lighter weight but greater light gathering power over a pocket binocular. But that raises an interesting question; which model is more versatile in the long run?

To begin to answer that question, I’ve spent some time comparing and contrasting the efficacy of two binoculars in these size classes; a Barr & Stroud Savannah 8 x 42, which I have written enthusiastically about in a past blog, and more recently, a Celestron Trailseeker 8 x 32, described in more detail here.

Let’s first look at the specifications of both models at a glance:

The Barr & Stroud 8 x 42

Fully multi-coated

Phase coated(probably silver or enhanced aluminium)

8.2 degree FOV(143m@1000m)

5.25mm exit pupil

18mm eye relief

Dry nitrogen purged

Waterproof

810g

Retail Price: £120 UK

The Celestron Trailseeker 8 x 32

Fully broadband multi-coated

Phase coated(high reflectivity dielectric coatings)

7.8 degree FOV(137m @1000m)

4mm exit pupil

15.6mm eye relief

Dry nitrogen purged

Waterproof

453g

Retail Price: £125(recently reduced for clearance owing to the discontinuation of the model)

Performance in Bright Daylight Conditions

Both instruments serve up  very sharp, high contrast images of well-illuminated targets with virtually no chromatic aberration(this is widely exagerrated by many reviewers but is actually not really an issue in any realistic situation. Indeed, in my comparison of smaller high-quality ED and non-ED instruments there has never been a target that I have imaged where ED glass made any meaningful difference to the viewing experience). The Celestron has a narrower field of view and a smaller ultra-sharp sweetspot. The Barr & Stroud displays a wider, flatter field with a noticeably larger sweetspot. The larger exit pupil on the latter makes viewing that little bit more comfortable, since positioning the eye over a larger shaft of light is easier to achieve. Both instruments generate images that are about equally bright under these conditions though. Near equal too is their ability to suppress glare and internal reflections owing to good baffling and high-quality coatings applied to all optical surfaces. The objective lenses are also deeply recessed in both binoculars, offering protection against rain, wind-blown dust, as well as serving as an effective barrier against peripheral glare.

I also noted slight differences between these instruments in colour tone when observing brightly illuminated daylight targets. The Celestron had a more neutral colour tone, whereas those of the Barr & Stroud were ever so slightly yellower and darker in comparison.

The focusing wheels on both instruments are notably different in field use however. The Barr & Stroud possess one of the best focusers I have personally experienced(indeed they have been very good in a number of other instruments marketed by the same company). It is buttery smooth and very easy to adjust in situations where rapid changes of focus are necessary. The Celestron focuser has much more tension in comparison, even after using it for a considerable number of hours in the field. When rapid focusing is required, the Barr & Stroud Savannah is clearly superior, which makes a significant difference when scanning fast-moving targets like birds flying across the field of view.

There is also a significant difference in eye relief between the two instruments. The Barr & Stroud has a whopping 18mm eye relief whereas the Celestron Trailseeker only exhibits 15.6mm in comparison. What this means in practice is that the latter is far more comfortable to use while using eyeglasses. I can see the entire field of the Savannah if I use my eyeglasses but it’s a lot more challenging with the Trailseeker.

The weight difference between the models is considerable however; with the Celestron tipping the scales at just over half the weight of the Barr & Stroud. Indeed the latter is one of the heaviest  8 x 42s currently available, while the Celestron Trailseeker is one of the lightest models in its aperture class. This has a significant  bearing on  prolonged use and transport in the field, where neck strain is effectively eliminated in the light-weight Celestron.

Low Light Performance

On paper, one would reasonably expect that the significantly larger 8 x 42 would prove better in low light conditions, such as those experienced at dawn and dusk, but my testing revealed some surprising results! In a nutshell, the Celestron Trailseeker proved to be much closer to the Barr & Stroud under such conditions! Immediately after sunset on several late January evenings, I found that both instruments produced very similar performance in terms of the brightness of the images garnered of a heavily lichen-adorned tree branch located some 50 metres off in the distance. Indeed, the 8 x 42 only pulled noticeaby ahead well into twilight when the last light of day was ebbing from the landscape. This seemed genuinely puzzling to me, as I fully expected the results to be well, like night and day.  But why though?

The first significant difference between the models relates to the coatings used on the roof prisms in both instruments. The Celestron Trailseeker has state-of-the-art dielectric coatings that significantly improve its light transmission over a similar sized model with lower reflectivity aluminium or silver coatings. Maybe the Trailseeker has better anti-reflection coatings applied to the lenses making up the objectives and the eyepieces? The second thing that I noted is the significantly larger frame of the Barr & Stroud Savannah, which will have commensurately larger prisms than the smaller Celestron, with the implication that more light will be absorbed while traversing the former. That said, I still couldn’t understand why an instrument with 42mm objectives was not pulling very far ahead under such low light conditions than an instrument with only 32mm aperture objectives. Quite frankly, it still didn’t add up!

It was then that I realised that the best explanation possibly pertained to the size of the exit pupil under the same conditions. As any amateur astronomer worth his/her salt will tell you, the pupil of the eye is designed such that it dilates in low light conditions to allow more light to reach the retina. Indeed, this is one of the ABCs in telescopic deep sky observing, where a fully dilated eye pupil shows you much fainter objects than eyes that are newly accustomed to the dark. But while some dilation certainly occurs under low light, I wondered whether there was a limit to how much dilation actually occurs during early twilight, when the differences were observed to be most similar in both instruments. If my eyes only extended from say 2.5mm during bright daylight to a liitle over 4mm in early twilight, the extra millimetre or so offered by the 8 x 42 would be of no significant benefit. Maybe my eyes were just not capable of using the 5.25mm offered up by the larger 8 x 42 under such conditions?

I also noted that the tests on both binoculars were carried out more or less simultaneously for the duration of about 15 minutes, so not long enough to induce big changes in the ratio of rhodopsin(which reaches higher concentrations in darker conditions) to retinal(which exhibits higher concentrations in bright light conditions) In addition, the eye takes quite a long time to effect these biochemical changes, and most certainly longer than the 15 minute duration over which these tests were conducted. Moreover, rhodopsin is still rather labile even in low light conditions such as those encountered during the twilight sessions. However, these findings were quite in keeping with the subsequent experiences I had with both binoculars under well-adapted dark conditions; specfically under a clear night sky with no Moon.

Dark Sky Performace Compared

Donning some dark sunglasses I sat out in a deck chair for about 25 minutes after leaving a bright indoor environment to accelerate dark-eye adaptation. By then I was sure that my eye pupils had dilated to their maximum extent and the process of rhodopsin biosynthesis was well under way. Examining the region centred on Orion’s belt stars, I immediately noted a very significant difference between the glasses; this time the clear winner was the 8x 42 Barr & Stroud binocular. It was easy to see that it was pulling in more numerous and fainter stars in Collinder 70 than the smaller 8 x 32. The same was true when I critically examined the Sword Handle of Orion, and in particular, the marvellous gaseous nebula of M42. The 8 x 42 was very much superior, indicating that my eyes were indeed gathering in more light( as they should do) owing to its larger exit pupil of the 8 x 42 binocular.

That said, the 8 x 32 was more comfortable to hold over prolonged periods(several minutes), owing to its much lower weight and transmitted a surprising amount of light; far more than any pocket glass (25mm aperture or less) I had recalled from memory, yielding quite impressive views of star fields and open clusters like the Auriga Messier trio, then very high overhead in the winter sky. The slower focus wheel on the Celestron was far less of a problem under these viewing conditions owing to the relatively tiny focus adjustments required when viewing astronomical targets, and especially when moving from the zenith to objects imaged nearer the horizon.

Overall Implications

The Barr & Sroud Savannah 8x 42(left) gets my winning vote over the Celestron Trailseeker 8 x 32(right).

So which instrument is more versatile? Unsurprisingly, this is a deeply personal choice and, as such, there are no absolute answers. If you don’t mind carrying around the extra weight, then the 8 x 42 would get my vote. I just love the way the instrument feels in my hands, its solid, Spartan construction, wonderfully sharp, super-wide field of view and spectacular bang for buck. The 8 x 42 is exceptionally easy on the eyes with its very comfortable 18mm eye relief(compared to the considerably tighter 15.6mm on the Celestron) and larger exit pupil, so pulling well ahead as an astronomical instrument, or when glassing under deep twilight conditions. It’s only significant downside over the 8 x 32 is its lack of dielectric coatings on the Schmidt-Pechan roof prisms, but it more than makes up for this with its fine optical quality and sturdy mechanical design. Indeed, the 8 x 42 Savannah remains this author’s personal favourite binocular!

But if weight is a big issue and you like to do all or nearly all of your glassing during daylight hours, then a high-quality 8 x 32 will certainly deliver the readies and thus deserve serious consideration.There are some other models in this binocular size class that are as good, if not better than the Celestron, and at prices that won’t leave you out in the cold; the Vortex Diamondback HD 8 x 32(with its famous ‘no questions asked’ VIP warranty), the Nikon Monarch 7( 8 x 30) and the Hawke Frontier X HD, immediately come to mind, all of which retail in the UK for between £200 and £300 and well worth checking out. If possible, you should try before you buy to avoid disappointment.

 

Thanks for reading!

 

Neil English is the author of several books on telescopes and astronomical observing, but does not endorse bling. He is seriously considering writing a similar text dedicated to binoculars in the future.

PostScriptum: I intend to have my fully dilated eye pupil size measured on my next visit to my optician.

De Fideli.

The War on Truth: The Triumph of Newtonianism Part II.

Octavius: when a ‘scope costing a few hundred pounds eats a £1500 refractor for breakfast, your telescopic worldview has to change……and it did!

Continued from Part I

New entries indicated by ***

Of late I have been observing primarily with my 8” f/5.9 reflector.  After collimation, I check the seeing via visual observation at moderately high power on tight and/or magnitude contrast doubles—this is how I happened on this pair of doubles in Draco.

STT 312AB and STF 2054AB appear to the naked eye as the single star Eta Draconis.  Starting in Ursa Minor, a straight-line path from Kochab through Pherkad gets me to Eta as shown in the annotated Cartes du Ciel screenshot below.

 

DRADblDblPath_GIMP.jpg

 

I like to start with the fainter pair, STF 2054AB which is  a mere 12’ due North of Eta Draconis.  In 2017 this mag 6.2/7.1 pair had a separation of 0.943”, which is in line with historical speckle data.  At 345x, I saw two whitish stars of slightly uneven magnitude that were clearly split with dark space between the stars.  I gauged the seeing by estimating how often the image sharpens to two distinct discs.

The 2nd Ed. of CDSA lists STF 2054 as a (2) + 1 triple, meaning the A component is really AaAb.  Stelle Doppie informs the AaAb pair is CHR 138AaAb with a separation of 0.222” (1990)—perhaps those with larger glass can see this as oblong?

Moving on to the brighter object, Eta Draconis or STT 312 AB is where the fun starts.  This mag 2.8/8.2 pair has a separation of 4.68” as measured by Gaia satellite (2015.5)  Using the same eyepiece you used for STF 2054AB, try to find the faint secondary without prior position angle knowledge.  It will be quite small and about 4.5x farther than the distance between the stars comprising STF 2054AB. 

My first attempt at detecting STT 312 B required almost a half hour of moving my eye from averted to direct vision before I definitively saw the tiny speck of light corresponding to the companion.  On a subsequent night, I found the secondary right away because I knew where (and how) to find it.  The more steadily the diminutive B presents as a dot of light, the better my seeing.  Of course, darker skies will also aid your efforts for seeing the faint companion. 

STF 2054AB and STT 312AB help me gauge my local seeing and are fun to look at.  Have you looked at these stars lately?

Nucleophile(Austin, Texas, USA): from an online thread entitled, Fun in Draco: Proximal Pairs STT 312AB and STF 2054AB

Perhaps the aforementioned objects are too easy and you desire a greater challenge; if so, head about 11 degrees due south of Eta Draconis to Hu 149

This pair of ~matched magnitude 7.5 stars has a separation of 0.66″ (last precise in 2017 = 0.665″; my own measure in 2017 = 0.662″)  The pair are slowly widening:  Burnham (1978) lists the separation at 0.5″

Using my 8″ reflector, I observed this object last night and logged the following observations:

345x:  image transforms from elongated to notched (snowman) about 30% of the time; both stars are light orange-yellow

460x:  now seen as sitting on the border of resolved to two discs and split with the tiniest of black space between the discs

Below is an inverted image of Hu 149 I assembled in 2017 using my 15″ reflector and an ASI178MC camera at f/23 operating in mono mode.

 

HU149_JDSO.jpg

Nucleophile(Austin Texas, USA), from an online thread entitled; Fun in Draco: Proximal Pairs STT 312AB and STF 2054AB

Attached are some recent pictures of these double stars.  In all cases, N is up and E is left.

I obtained the images using my 15″ reflector and an ASI 290MM cooled CMOS camera.  An imaging train of Paracorr type 1 (setting 5), Powermate 2.5x and a Baader Orange filter gives an f ratio of 13.3  Images were collected using either SharpCap or Firecapture. 

Measures were made with Speckle ToolBox.  Composite images were assembled in Registax.

First up is STF 2054AB

STF2054AB_DRA.jpg

Dear Mark,

Thanks a lot for your interesting and well-documented presentation of a pair of doubles so well suited to gauging seeing  all year round. Last night I made these my first port of call with a 140mm Maksutov (an OMC 140 made by Orion UK, a good instrument). The physics suggest that the separation of 0.943” which you state for STF 2054AB is at the physical limit possible with this aperture, so I was keen to find out how I would fare.

The day had been hot, seeing was mediocre. I know from experience, though, that the air may calm down in certain phases of the evening, so I just hoped I would catch a good moment. At 75x I saw no hint of a companion of Eta Draconis, but STF 2054AB was definitely elongated. At 130x still no sign of Eta’s companion, but the elongation of STF 2054 became even more evident and it was clear at which end the weaker component stood. Encouraged by this, I went up to 210x. Now STF 2054 was a stretched figure-8 that popped apart into separate discs in better moments of seeing. Somehow quite charming!

I had gone in without PA knowledge and estimated this at 330°. Stelledoppie says 351°. So deviation <10%, that’s OK.

After having trained the eye in this manner, I turned my attention to Eta Draconis at 210x. All I could spot was a disc within a wildly dancing diffraction pattern. Although the B component, with its separation of 4.68”, is more than 4.5x further than the distance between STF 2054 A and B, it is evidently much harder to spot. This was an interesting lesson in the effect of Delta-Mag.

I find STF 2054 quite charming and Eta quite challenging, and will certainly be returning to them often. So thanks again, Mark.

CS, Christopher

C.Hay(Germany), from an online thread entitled; Fun in Draco: Proximal Pairs STT 312AB and STF 2054AB

Finally, here is Hu 149

I measured this one 21 times over three nights in order to gauge repeatability of the measuring protocol.  The current measure matches very well what I obtained a few years back.

Hu149_DRA.jpg

rugby, on 19 Jun 2019 – 06:11 AM, said:

I just finished observing STF 2054 AB and STT 312 in Draco using an  SW 120 ED and a Meade LX 10. A very bright moon with Jupiter brightened the eastern horizon.  Unfortunately these pairs lie directly above my house and thus suffer from heat rising from the roof.

What I saw was surprising. 2054 was elongated but not separated in the 120 at 200x.  I had not expected anything because it is on the edge of this scope’s capabilities. I did not try the 8 inch.

STT 312 AB was exceedingly difficult. Without prior knowledge of PA I kept seeing flashes of a tint dot south south preceeding the primary. I used the 120 at 200x. The view in the 8 inch was too turbulent for any resolution.

I am notoriousy poor in estimating position angle.

Hi Rugby,

Give ’em a try with your 8″–I think you will like the views!

Nucleophile( Austin Texas, USA), from an online thread entitled; Fun in Draco: Proximal Pairs STT 312AB and STF 2054AB.

Last night was about my 10th try to find that little bugger hanging out in the diffraction ring. I had tried repeatedly and without success with my 120mm ED. I’ve tried before with my 8″ [Newtonian], even on an EQ platform a few nights ago. This time I managed to see it with the 8″ at an ungodly 498x without the EQ, so constant nudging and then allowing it to drift (if the drifting was near rapids) . I would call it my “great white whale”, but it’s more like a tiny white pimple.

You’d expect the 8″ should easily split it, if I could just get improved seeing.

Chesterguy

Chesterguy( Stillwater, Oklahoma, USA), from an online thread entitled: Zeta Herculis…finally!

 

Well, I confirmed my sighting of Zeta Herculis las night. Same instrument, equal or better seeing and this time on my EQ Platform. Despite not getting my platform aligned perfectly on Polaris because it was blocked by my house, I still managed enough accuracy so that, while it drifted through the EP, it wasn’t like the prior night. Still a tough split at 498x in my typical seeing. I salute those of you who are splitting it below 140mm.

Chesterguy(Stillwater, Oklahoma, USA), from an online thread entitled: Zeta Herculis…finally!

I observed this double with the 8″ reflector twice in recent days:

345x:  just split with smaller secondary appearing yellow against bright white primary; secondary appears to be sitting between first and second diffraction rings

314x:  when seeing permits, the yellowish secondary is seen sitting atop the primary

I did a few Aberrator simulations for the expected view using either my 8″ or 15″ reflectors; these are shown below.

 

ZetHERAberrator_Gimp.jpg

The 8″ inch simulation is fairly close to what I saw.  The 15″ simulation shows the secondary now sitting near the second diffraction ring.  In some images I obtained recently with the 15″ and an ASI 290MM camera this is pretty much what I saw.  In the composite image below the first diffraction ring appears as a fuzzy halo while second ring got washed out a bit in processing.

 

STF2084_Zeta_HER.jpg

Nucleophile(Austin, Texas, USA), from an online thread entitled; Zeta Herculis…finally!

I just made a 7 inch aperture stop today for my 18. Worked great tonight. I’ve made them many times before but it’s been a while. Seeing tonight was so good the better views were at full aperture..

Darren Drake(Chicago, USA), from an online thread entitled Aperture Mask

DavidC, on 19 Jun 2019 – 03:41 AM, said:

I am making an off axis aperture mask for my 10 inch lightbridge, but using a single 4 inch hole. I got the idea from san francisco sidewalk astronomers, but they had it as plans for a solar filter. I’m making it for planets and double stars. I’ve been told by stepping the aperture down to 4 inches, planets won’t be as bright, therefore I can use more power on them. At 1270 mm focal length, I’m hoping for impressive views on planets by using more power. Am I thinking this correctly?

 

Thanx, David

Waste of time IMO. I have a 10” LB with a very good mirror set. I also have excellent 100 and 120 mm ED refractors. If seeing is equal, the 10” reflector slaughters the excellent refractors in planetary detail.

SteveG(Seattle, Washington, USA), from an online thread entitled: Aperture Mask

Vla, on 20 Jun 2019 – 2:55 PM, said:

Smooth edges have more of a cosmetic effect. Rough edges don’t induce aberrations, because they don’t affect wavefront shape, and unless the edge is ridiculously rough, the diffraction effect will be negligible. As an illustration, effect of a 2-inch focuser protruding into the light path of a 200mm diameter mirror. As much as 1 inch into the light path will take only about 1% of the energy out of the central maxima (which, expectedly, becomes somewhat elongated, because the vertical mirror diameter is effectively shorter).

Yes indeed! The effects are diffractive and tiny, not what we optics guys call aberrations. I also like your focuser signature there… Fourier Transform (impulse-response) says it all.

Masks roughly-cut with scissors or a knife are perfectly fine. The one thing to try to avoid is long straight edges. Those will give noticeable spikes. The three straight edges of the focuser there… do a little bit of that.

On the tech/theory side… there are infinitely many wavefronts that will produce the same impulse response. That’s because the sensor (eye or camera) detects only amplitude, but not phase. So you can’t inverse-transform back to the wavefront by processing on the one image of a star… unless you use two or more (ideally many) focus positions’ images. And that is what we call ~phase diversity analysis~ (what was used to assess Hubble’s flaw). And what is implicitly involved in the various casual ~Sar Tests~ that we often talk about here. 

Tom Dey(Springwater, New York, USA), from an online thread entitled: Aperture Mask

Deep13, on 14 Dec 2018 – 06:56 AM, said:

In my mind, the ideal planet telescope is a 10 or 12″ EQ Newt (split ring?) in a permanent location with a clear view of the south and overhead. Add a good binoviewer, pairs of long ZAOs, and an easy way to reach the EP, and I’d be all set. In reality, it would be too expensive and I have no place to set it up permanently. So-o-o-o, I’ve arranged to buy a used 8″ f/8 EQ-mounted Newt. I’ll need to have some servicing done on the mirrors. I’m thinking that within the realm of likely possibility, this may very well be my ideal set-up. Right now it has no fan and a tall R&P focuser, so I may change those things. And I’ll built a cart for the Meade RG mount. I already have a tall adjustable chair and a Denk II with pairs of TV Ploessls.

 

Any thoughts? What’s your ideal planet scope?

 

I had both a very good 8″ Zambuto f-7.5 and a 10″ Waite f-5.8 on an EQ mount, the 8″ I had rotating rings but still a very big pain in the rear to use on an EQ mount. I am considering a slightly different set up 10″ f-5.3 through f-5.5 for a shorter tube and mounted on an EQ-AZ mount, in AZ mode viewing will be far more easier as the EP will be on one side and accessible.  At the focal lengths mentioned as long as you get a premium mirror and build it well you can achieve 50x per inch with sharp image on the planets, and you can use a 1.83″ secondary, CO 18.3%. good luck.

dag55(Hamburg, Illinois, USA), from an online thread entitled; Ideal Planetary Scope

The Orion 4.5 in f/8 dobsonian could be an option. Seems to get good reviews on the optics here on CN. Lightwieght. I believe the focuser is plastic, but, it should be ok with normal weight 1.25in eps.If the moon with a 4 -5 in reflector is the ojective, this little scope should do a decent job.I have not used the Orion, however, I do have a 4.5in f/8, and I think they are capable little scopes.

Good viewing,

dmgriff, from an online thread entitled, 4-5” reflector recommendation

 

+1 on the AWB OneSky.

I was surprised at how well it works. At 14 pounds total, it might be just what you’re looking for.

Havasman( Dallas, Texas, USA), from an online thread entitled: 4-5” reflector recommendation

The AWB One Sky is fine for the money but its burdened with an very poor helical focuser, preferable is the Lightbridge 130 , discontinued but still available from some dealers, the Zhumell 130, the best of the bunch IMHO or the slightly smaller Zhumell 114 , very similar to the Orion Starblast but less money, the Zhumell is also sold as the Edmund Astroscan Millenium, D.

Binojunky, from an online thread entitled: 4-5” reflector recommendation

 

The Onesky is a fine scope. I have no problem with the focuser.,and the mount is quite stable.,Some of my best spent astro money.,cheers.,

Attached Thumbnails

  • 20190327_183143.jpg

 

Clearwaterdave(Western Maine, USA), from an online thread entitled: 4-5” reflector recommendation

How is a 4″ apo a “no brainer” when the OP specificly asked about a reflector? The OP has other scopes and seems to have some idea of what he’s lookin for.,What scope you think would do a better job for doubles or planets is not what he asked about. If you have used and liked a 4-5″ reflector of any type and you want to share your experience here that would be helpful to the OP.,waytogo.gif

Clearwaterdave(Western Maine, USA), from an online thread entitled: 4-5” reflector recommendation

I have had the OS up next to a 102ed and “to my eyes” the views are too similar for me to say either one was “better”.,And there are many many very happy OS owners.,So yes.,you can expect a quality reflector for $200.,That’s the no brainer.,and the OS isn’t the only one.,there are a few good quality 5″ reflectors out there for $200.,YOMV.,

Clearwaterdave(Western Maine, USA), from an online thread entitled: 4-5” reflector recommendation

Thank you again for all the great responses. I’m always pleasantly surprised at the information you guys have and your experience. Yes, optics are my primary concern for the scope, but I haven’t really read one bad review concerning them so I think the OneSky is what I’ll go with. I have a pretty large back deck with a decent view to the south so it will be easy to track the moon every night, even if only for a few minutes. Concerning refractors: the truth is I have little experience with them (I know they’re not hard to figure out) and my comfort level, if you will, is with Dobsonian type reflectors. I have a neighbor down the road who has a 4” Takahashi (I think), and the views through it are really something else. Then he told me the price tag and my mind went to how how big of a Renegade or Teeter I could get for the same price. Plus someone told me that owning a refractor will lead you down to the perilous and very expensive road of astrophotography.
The reason I don’t put the 8” out on the back deck is that I use it specifically for planetary viewing now. I have it in the garage ready to load up for a quick drive into the foothills next to the house. The view is better and I get away from all the house and street lights. At f/7 that 8” gives just wonderful views of the planets. I was also able to complete the AL double star program with. If you haven’t looked at that program, I recommend it as it was one of my favorites to do. The 8” was the first scope I ever owned and I had to rebuild it out of disassembled parts, which I found at a flea market. That was a journey, let me tell me you. But now it’s dialed in with a great mirror and I’ll have it forever.
And with the 10”: that’s my deep-sky, dark site, fall into the heavens scope. I try to get out there at least once, if not twice, a week. It too has great mirror and makes it hard for me to financially justify a larger scope given there’s so much to see with it.
Back to the OneSky. Hopefully it will be what I’m looking for. I have perfect cover and place for it, it won’t get dirty, and when I’m out enjoying the late evening and want a quick peak, it’ll be right there.

Mick Christopher, from an online thread entitled: 4-5” reflector recommendation

One of my all-time favorite 4ish inch scopes is the Orion XT4.5, mentioned by Dave and Ed earlier. It’s a very nicely engineered and accessorized product, and provides sharp high power views with very minimal focus wiggles and immediate dampening times. The long focal length makes the scope forgiving of the somewhat imprecise focuser, which works quite well. It’s also very easy on simple eyepieces, which is handy. It’s not a do-all scope, owing to the focal length and 1.25″ ep limitation, but it’s still capable of providing pleasant low power views, yet shines at moderate and high powers. Add a 5 gallon bucket, inverted, as a “chair” (which can pull double duty as a caddy for charts, ep case, and binos) , and the scope works well for adults without the need to raise the scope on a platform.

KerryR( Midwest Coast, Michigan, USA), from an online thread entitled: 4-5” reflector recommendation

 

If the OP can handle the extra size and cost the Orion XT6″F8 is a fine scope, I picked mine up last years for $300 Canadian brand new shipped to my door, take it out in two pieces, plonk it on the ground and away you go, D.

Binojunky, from an online thread entitled: 4-5” reflector recommendation

 

This report is the third installment of a series of observational investigations I have made using an 8 inch f/5.9 reflecting telescope. 

Check out this link for goals and methods used in this study:

https://www.cloudyni…-and-monoceros/

Corvus
Bu 920 (12158-2321) mags 6.86/8.22; pa = 308°; sep = 1.934”, 2016 (solid data)
345x:  well split with secondary a bit smaller; both stars are yellow; well above resolution limit

B 1716 (12247-2004) mags 9.42/9.42; pa = 230°; sep = 0.701”, 2014 (solid data)
345x:  single star
460x:  a bit elongated, but never resolved despite best efforts; below resolution limit; important data point to set lower limit for fainter stars

Hydra
STF 1273 AB, C (08468+0625) mags 3.49/6.66; pa = 310°; sep = 2.824”, orbital estimate for 2019.3 (solid data)
345x:  easily split to two yellow stars of widely varying magnitude; above resolution limit

Bu 587 AB (08516-0711) mags 5.75/7.41; pa = 121°; sep = 1.186”, 2017 (solid data)
345x:  blur of light that sharpens to a small secondary that is just split
460x:  spit 100% of time; above resolution limit

Bu 219 (10216-2232) mags 6.70/8.52; pa = 186°; sep = 1.773”, 2015.5 (Gaia DR2, solid data)
345x:  split 100% of time; secondary is much smaller and both stars are white; above resolution limit

A 3064 (08403-1518) mags 9.15/9.00; pa = 357°; sep = 0.681”, 2015.5 (Gaia DR2, solid data)
345x:  just resolved to two tiny discs 40% of time; just above resolution limit; important data point to helps set minimum value of rho for faint, equal mag pair

A 338 (08207-0510) mags 8.83/9.39; pa = 17°; sep = 0.569”, 2015.5 (Gaia DR2, solid data)
345x:  slightly pointy
460x:  slightly elongated, but never resolved; well below resolution limit

HJ 4478 (11529-3354) mags 4.67/5.47; pa = 52°; sep = 0.578”, 2015 (data needs confirmation)
627x/orange filter:  elongated that becomes notched 10% of time; just below resolution limit; difficult due to low altitude; requires re-measure to firm up separation value

B 1175 (10582-3540) mags 8.25/9.23; pa = 251°; sep = 0.61”, 1998 (data is old, scant)
345x:  resolved 50% time to two similar magnitude yellow stars; a bit above resolution limit; separation likely greater now; requires newer measures of separation and delta mag

B 218 (12002-2706) mags 9.11/9.69; pa = 340°; sep = 0.472”, 2015.5 (Gaia DR2, scant data)
627x:  very faint; rod shaped at times, but no hint of resolution or notch; well below resolution limit; requires re-measure to firm up separation data

HWE 72 (12136-3348) mags 6.48/8.55; pa = 159°; sep = 1.231“, 2016 (solid data)
345x:  just split 30% of time to two white stars; secondary is much smaller; above resolution limit

Bu 411 (10361-2641) mags 6.68/7.77; pa = 303°; sep = 1.33”, 2017 (solid data)
345x:  just split 100% time to two light yellow stars of somewhat dissimilar magnitude; above resolution limit

Bu 219 (10216-2232) mags 6.70/8.52; pa = 186°; sep = 1.773”, 2015.5 (Gaia DR2, solid data)
345x:  split 100% time; secondary is much smaller and both stars are white; above resolution limit

Leo Minor
STF 1406, aka STT 211 (10056+3105) mags 8.37/9.42; pa = 219°; sep = 0.728”, 2017 (solid data)
345x:  just split from resolved 30% time; stars are faint, white, and seem to be of similar magnitude; above resolution limit; a newer delta mag measure desired

Lynx
STT 159AB (06573+5825) mags 4.45/5.50; pa = 236°; sep = 0.704”, orbital estimate for 2019.3 (solid data)
345x:  single star
460x:  possibly pointy
627x:  at times elongated showing secondary as smaller, but never resolved; below resolution limit; it is unclear why this is so difficult—perhaps there is a ‘brightness’ factor that needs to be incorporated?  Revisit next year using orange filter and get a new measure.

COU 2607 (07441+5026) mags 5.33/8.43; pa = 164°; sep = 0.973”, 2012 (data is a bit old but is considered solid)
460x:  secondary pops into view as just split 50% of time; just above resolution limit

STT 174 (07359+4302) mags 6.62/8.26; pa = 92°; sep 2.170“, 2015.5 (Gaia DR2, solid data)
345x:  split 100% of time; both stars are white and secondary is much smaller; fine mag contrast double; well above resolution limit

Hu 850 (08094+3734) mags 9.42/9.23; pa = 349°; sep = 0.57“, 2016 (scant data)
345x:  viewed for an extended period of time using averted vision shows the pair exhibiting a notch just past extended a mere 10% of the time; never resolved and is considered below the resolution limit; a re-measure of separation is needed

Ursa Major
STT 232AB (11151+3735) mags 8.02/8.90; pa = 243°; sep = 0.623”, 2015.5 (Gaia DR2, solid data)
552x (Pentax 2.5XO/Paracorr Type 1, setting 1):  pointy about 25% of time, but never a hint of being resolved; below resolution limit

STT 235AB (11323+6105) mags 5.69/7.55; pa = 44°; sep = 0.949”, 2019.3 (orbital estimate, solid data)
345x:  on the resolved/split border with secondary seen as much smaller
460x:  cleanly split; primary is yellow, secondary is light orange; above resolution limit

STF 1770 (13377+5043) mags 6.93/8.18; pa = 128°; sep = 1.722“, 2015.5 (Gaia DR2, solid data)
345x:  cleanly split; primary is light yellow while the smaller secondary is light orange—a fine pair; above resolution limit

STT 200 (09249+5134) mags 6.53/8.57; pa = 337°; sep = 1.251”, 2015.5 (Gaia DR2, solid data)
345x:  close split (AV helps to see fainter secondary)
460x:  easily split to two stars of unequal magnitude—very nice; above resolution limit

STT 232AB (11151+3735) mags 8.02/8.90; pa = 243°; sep = 0.623“, 2015.5 (Gaia DR2, solid data)
552x (Pentax 2.5XO/Paracorr Type 1, setting 1):  pointy about 25% of time, but never a hint of resolution; below resolution limit—important data point for calculator development

A 1346 (09591+5316) mags 8.84/9.66; pa = 179°; sep = 0.624“, 2019.3 (orbital estimate; data is incongruent between orbital estimate, historical speckle and Gaia DR2)
345x:  slightly elongated; very difficult
460x:  moves past elongated to notched <10% of time
627x:  possibly seen as resolved 10% of time with averted vision; just below resolution limit; requires re-measure to firm up separation value

STT 229 (10480+4107) mags 7.62/7.92; pa = 254°; sep = 0.63“, 2019 (estimate from 4th Interferometric Catalog; data incongruent between historical speckle, orbital estimate and last precise)
345x:  moves past pointy to resolved 30% of time showing secondary as a bit smaller versus the primary
460x:  persistent snowman shape that sharpens to nearly split 30% of time; just above resolution limit; re-measure of separation needed for this important data point

Bu 1077AB Dubhe (11037+6145) mags 2.02/4.95; pa = 336°; sep = 0.802“, 2019.4 (orbital estimate, solid data)
460x/orange filter:  very difficult; secondary pops into view 30% of time as just split—otherwise, it is merely a blur of light/brightening of first diffraction ring; at or just above resolution limit

**Have you observed or imaged any of these objects recently?  Let me know.  Perhaps you have a suggestion for a double I should observe—I’m all ears!

Nucleophile(Austin, Texas, USA), from an online thread entitled; Investigations With an 8 Inch Reflector. Part I: Canis Major, Canis Minor, Lepus, and Monoceros

My preference is in the “or” category. I have used all of my scopes for doubles, but I love my 10 inch reflector… it is a double star magician… except for Sirius B… just can’t get that one in the 10 inch. But I have split it ONCE with my 4 inch achro (retired this one to give to my granddaughter)… she loves doubles too…

SeaBee1, from an online thread entitled; scope preference for doubles

I use my Stellarvue 105mm APO most of the time for doubles wider than 1″ and when the seeing is only fair.  It gives such nice images with no central obstruction.

If the seeing is above average I use the Intes 180mm Mak-Cass with its astro-sital 1/9 wave optical system on the tighter doubles, and planets.

I don’t usually use the 10″ LX 200 on doubles, but one night when the seeing was very good I was using the Baader 8-24 zoom on the double double in Lyra and zoomed all the way to 660x,  the stars looked perfect and the separation was enormous.

I usually don’t use my 18″ Obsession for doubles, but once while doing a two star alignment on Antares with my 12.5mm cross-hair eyepiece, there it was a bright orange star with a little green orb next to it.  I hade to just stop and take a good long look, it was beautiful, and so was the seeing that night.

Astromaster; from an online thread entitled; scope preference for doubles

Last seen this star for a long time. Seeing that the closer stars that I knew are either already inaccessible (too close) or have gone beyond the horizon, I decided to observe those that are less mobile. In particular, this one. Since there are days with an excellent atmosphere and they should be used. In comparison with the double in the zet boo, this star looks obviously wider and accessible. It is interesting that the difference in the sizes of fragments of diffraction disks is visible. This is quite unexpected, considering that the difference in brightness is only 0.2. Maybe this star is variable? and therefore I see that parts of diffraction discolves of different sizes (this happens when the difference in brightness is more than 1 … 1.5 magnitudes). This is weird.  I used a large piece of paper to accurately mark the track of the star and its position. Such dimensions allowed me quite accurately, without using devices, to note how exactly the disc is stretched..eta crb1.png
Constantin 1980, from an online thread entitled: Observation Eta CrB (0,38 “) 9\04\2019

This report is the fourth installment of a series of observational investigations I have made using an 8 inch f/5.9 reflecting telescope. 

Check out this link for goals and methods used in this study:

https://www.cloudyni…-and-monoceros/

Bootes
BU 224 (14135+1234) mags 8.94/9.35; pa = 95°; sep = 0.65“, 2015 (last precise; not solid, opening)
345x:  single star
460x:  pointy but never resolved; well below resolution limit; magnitude data is from Hipparcos (1991, 515nm); needs a re-msre of delta mag and separation

 

STT 287 (14515+4456) mags 8.40/8.62; pa = 5°; sep = 0.575“, 2017 (last precise vs 0.659” orbital estimate for 2019.3; data incongruent)
345x:  seen as elongated 30% of time
460x/averted vision/extended viewing:  elongated only, never resolved; below resolution limit; needs a re-msre of separation

 

STF 1866 (14417+0932) mags 8.48/8.65; pa = 205°; sep = 0.733“, 2015.5 (Gaia DR2, solid data)
345x:  on the border of resolved and split to two even magnitude light yellow stars; above resolution limit

 

STF 1863 (14380+5135) mags 7.71/7.80; pa = 60°; sep = 0.654“, 2017, (last precise, solid data)
460x/orange filter/averted vision/extended viewing:  moves past elongated to resolved 20% of time
627x/orange filter: just resolved 50% of time; just a bit above resolution limit; important data point (equal mag pair) to set minimum value of rho

 

STF 1867 (14407+3117) mags 8.36/8.83; pa = 355°; sep =0.674“, 2017 (data needs confirmation)
460x:  just split 50% of time to two white stars of slightly dissimilar magnitude; need re-msre of separation

 

A 148 (14220+5107) mags 8.32/8.96; pa = 190°; sep = 0.535“, 2019.3 (4th Int. Catalog estimate vs 0.58” last precise in 2015; data not solid)
627x:  a bit elongated but never resolved; well below resolution limit; need re-msre of separation

 

KUI 66 (14148+1006) mags 5.44/8.43; pa = 111°; sep = 0.99“, (my own measure in 2017 with ASI 178MC camera; data tentatively considered solid as it is a match with 4th Int. Cat. estimate)
627x/orange filter:  much smaller secondary seen as a resolved dot very near first diffraction ring 30% of time; just above resolution limit; important, large delta mag data point so re-msre with ASI 290MM camera needed.  See image below.

 

AGC 6 (14339+2949) mags 9.81/10.30; pa = 133°; sep = 0.752“, 2015.5 (Gaia DR2, solid data)
345x/extended viewing:  seen as elongated rod, never resolved; very faint and difficult; below resolution limit; important data point to set ‘faintness factor’

 

STT 298AB (15360+3948) mags 7.16/8.44; pa = 187°; sep = 1.208“, 2019.4 (orbital estimate, solid data)
345x:  easily split to two small light yellow stars of similar magnitude; very pretty; above resolution limit

 

A 1110AB (14497+0759) mags 7.69/7.93; pa = 245°; sep = 0.692“, 2015.5 (Gaia DR2, solid data)
345x:  oscillates between resolved and split; both stars are yellow with secondary seen as smaller and *delta mag is likely >0.24
460x:  seen as split 100% of time with secondary possessing a hint of orange; above resolution limit; Gaia DR2 gives a delta mag of 0.67 which does not agree with Tycho value of 0.24—will attempt a measure of delta mag to rectify

 

Canes Venatici
STF 1606 (12108+3953) mags 7.44/7.93; pa = 145°; sep = 0.611“, 2019.3 (orbital estimate vs 0.627”, last precise in 2017; data not solid)
460x:  elongated but never resolved
627x:  moves past notched rod to resolved 20% of time; at or just above resolution limit; observation supports tighter value of rho [0.611”]; this is an important data point; will re-msre (possibly annually) to firm up value

 

STT 251 (12291+3123) mags 8.35/9.27; pa = 61°; sep = 0.781“, 2017 (last precise; data not solid)
345x:  just resolved 30% of time with secondary much smaller
460x:  just split 50% of time; a bit above resolution limit; faint secondary plays role in difficulty; re-msre of separation needed

 

STF 1768AB (13375+3618) mags 4.98/6.95; pa = 95°; sep = 1.656“, 2019.3 (orbital estimate; solid data)
345x:  well split, primary is white and secondary is light yellow and considerably smaller—a fine sight!  Above resolution limit

 

Coma Berenices
STF 1639AB (12244+2535) mags 6.74/7.83; pa = 324°; sep = 1.855“, 2019.3 (orbital estimate; solid data)
345x:  well split, primary is white and secondary is light yellow; very pretty mag contrast pair; above resolution limit

 

STF 1687 (12533+2115) mags 5.15/7.08; pa = 200°; sep = 1.18“, 2018 (last precise; solid data)
345x:  a bit past just split 100% time with secondary noticeably smaller; both stars are yellow; above resolution limit

 

COU 397 (12575+2457) mags 9.06/9.71; pa = 63°; sep = 0.70“, 2015 (last precise; solid data)
345x:  single star; faint!
460x/averted vision:  slightly elongated but never resolved; below resolution limit; important data point to establish ‘faintness factor’

 

A 567 (13328+2421) mags 6.21/9.71; pa = 256°; sep = 1.450“, 2015.5 (Gaia DR2, solid data)
345x:  secondary seen as split 50% time and appears as very small, very faint dot a bit past first diffraction ring of primary; above resolution limit

 

Ursa Minor
STF 1989 (15396+7959) mags 7.32/8.15; pa = 23°; sep = 0.67“, 2013 (last precise vs 0.603”, orbital estimate for 2019.4; data not solid)
345x:  moves past elongated to exhibit a snowman shape
460x:  resolved about 40% time with secondary a bit smaller; above resolution limit (observation supports separation closer to 0.67” value; re-msre of separation needed)

 

BU 799AB (13048+7302) mags 6.60/8.45; pa = 265°; sep = 1.39“, 2017 (last precise; solid data)
345x:  easily split; both stars are white and secondary is considerably smaller—very pretty; above resolution limit.

 

A 1136 (16135+7147) mags 9.22/9.47; pa = 9°; sep = 0.727“, 2007 (last precise, data is old)
345x:  barely split; both stars are very small and white, and secondary is just a bit smaller; helps to establish ‘faintness factor’; above resolution limit; a re-msre of separation is needed

 

Virgo
BU 797AB (12345+0558) mags 9.10/9.39; pa = 146°; sep = 0.61“, 2010 (last precise, data is a bit old but considered solid)
345x/averted vision/extended viewing:  slightly pointy
460x:  elongated and on the border of resolved, but never did resolve despite an extended view
627x:  moved past elongated to resolved about 5% of time; at or slightly below resolution limit; a very important data point that warranted 45 mins of study under very good seeing conditions

 

RST 4484 (11447-0431) mags 8.46/8.39; pa = 64°; sep = 0.738“, 2017 (last precise; data not solid)
345x:  just split to two ~even magnitude yellowish-white stars—beautiful!  Above resolution limit; re-msre of separation needed

 

BU 935AB (13459-1226) mags 5.66/8.47; pa = 304°; sep = 1.03“, 2001 (last precise; data is old)
460x:  brightening of first diffraction ring sharpens to much smaller secondary 30% of time; both stars are yellow; above resolution limit; a new measure of separation is needed for this important mag contrast binary

Have you observed or imaged any of these objects recently?  Let me know.  Do you have a suggestion for a double I should observe within one of these constellations?  I would like to hear about it.

Nucleophile(Austin, Texas, USA), form an online thread entitled, 8 Inch Reflector Investigations. Part IV: Bootes, Canes Venatici, Coma Berenices, Ursa Minor, and Virgo

Here is an image of KUI 66 I obtained in 2017 using an ASI178MC camera operating in mono mode.

 

KUI66_JDSO.jpg

Cool, another crop! Here’s some of mine for comparison:

STT 287, 552x 12.5”. Wow! Hair-split, ~0.7″, near equal or half a delta mag.

STF 1867, 552x 12:5”. 0.5 delta mag, hair to figure 8 split, white. Not especially good seeing

Kui 66: 12.5” Unresolved faint haze at 553x, but adding the apodizing mask I had a glimpse of the B star 15% of the time, very small and faint, ~3″ and 4-5 delta mag. Both orange. Definitely there.

STT 289: 8″ 205x: Noticed a very much fainter star emerge with averted vision then could hold direct. Very fine, well split. 8″ 410x: Tried to bring out the B star with higher magnification, but oddly it disappeared. Curious. 20″ 410x: B star easily seen though the disks are bloated, seeing not good.

STT 298. 12.5” 552x Wow! Almost didn’t look at this one since it was split in the 80mm finder. One component is a close equal pair, ~2″.

STT 251. 12.5” 553x: Decidedly not round disk — there’s also a brightening in the diffraction — but not really split.

STF 1768: 8″ 205x: Very tight pair, a little more than hairline split, ~2 delta mag. 8″ 333x: white and dull blue, ~1″, split, Nice!

STF 1768. 12.5: 553x: Very pretty pale yellow and orange, 2-3 delta mag, ~2″

STF 1639: 8” 205x White and slightly blue pair; close, around 3″ [overestimated the split, it was so clean!]

STF 1687: 12.5” 553x = 35 Com: Bright orange & fainter B, showpiece, ~1.5″

A 567: 12.5” 553x: very faint B, very close, ~1″ when seeing stills, 3-4 delta magnitude. Surprised it is not so difficult. B looks like it doesn’t have any light of its own and is illuminated by A.

BU 935 = 86 Vir: 12.5” Pretty orange star but @ 553x poor seeing won’t allow split of 3 delta mag, 1.2″ B.

mccarthymark(San Francisco Bay Area, California, USA), form an online thread entitled; 8 Inch Reflector Investigations. Part IV: Bootes, Canes Venatici, Coma Berenices, Ursa Minor, and Virgo

Excellent info, Mark.

my notes on your notes:

a.  STT 287, inclined to think it is tight–like 0.6″  I will def msre next year.

b.  the much studied KUI 66, nice use of mask to glimpse the companion!  I used an orange filter and very high power on an excellent night

c.  STT 289–I will add this large delta mag object to my list (thanks!)

d.  STT 298AB  something is askew here with the delta mag as both of us describe the mags as being similar–I didn’t catch this first time around but have made a note for next year to try and get a msre of delta mag for this one; I looked back into my log notebook and also noted:  “tiny headlights; beautiful!”  Additional note based on the 4th Int Cat.:  the same year as the Tycho mag values [as listed in the WDS] are those from Hipparcos (albeit at a slightly shorter wavelength = 511nm) which found  the magnitudes to be 7.59 and 7.78–a much closer match to what we observed.  This is humorous:  WDS notes say the ‘D’ component at 167″ is actually a galaxy (possibly a quasar)!  How’s that for ‘optical illusions’  At mag 14, I will be chasing that one for sure with the 15″ scope.

e.  STT 251 was surprisingly difficult for both of us…

f.  BU 935  you may wish to give this one another shot on a night of very good seeing; it is difficult

Nucleophile(Austin, Texas, USA), form an online thread entitled, 8 Inch Reflector Investigations. Part IV: Bootes, Canes Venatici, Coma Berenices, Ursa Minor, and Virgo

Here is a composite image of A 1110AB taken in 2017 with the ASI 178MC camera.  The image supports a delta mag of >0.24

My measured value differs quite a bit from that of Gaia DR2 (0.692″) for this object.

 

A1110AB_JDSO.jpg

Nucleophile(Austin, Texas, USA), form an online thread entitled, 8 Inch Reflector Investigations. Part IV: Bootes, Canes Venatici, Coma Berenices, Ursa Minor, and Virgo

    So much for Newtonians not being suitable for observing high-resolution double stars eh?

    Mr. Hardglass

     

    Sol, that the primary is 8.38″ in diameter is a revelation. I assumed it was the standard 7.9″. When I stow it away for the monsoon, I need to measure it. That’s kind of cool, but definitely non standard for a Newt, yea? I wonder if they are using 8″ SCT blanks that are (supposed to be) a little bit ‘over sized’. Just curious.

    When I do the math for a 2.6mm diagonal support, I get 2.6/8.38 = 31% obstruction. Not a ton of difference, but comforting to some. My MCT has a 30% +/- obstruction and offers no ill feelings. The images are nice. It should have the contrast of a 8.38 – 2.6 = 5.8″ refractor, and you do not hear folks complaining about those views. It still puts ~90% of the maximum light into the Airy disc compared to a perfect 5.8″ APO. It’s right at the diffraction limit with a descent (not premium) mirror.

    Abytec(Pampanga, Philippines), form an online thread entitled: ES Firstlight 8inch dob vs. Skywatcher 8inch dob

    Actually I took lots of measurements regarding the E.S. 8, and measured many times. Not because I was obsessively compelled to, but I had an opportunity to acquire another 8″ mirror with a “pedigree”. So I needed to know if I would be able to use the E.S with little if any modification for an actual 8″ diameter with a traditional 1.4″ thickness to work.

    To the original O.P. the stock E.S. primary is also 7/8″ thick so the 6 point floating cell is just another little plus for the E.S. over the GSO or Synta.

    With the stock E.S. 8 that’s well collimated and cooled Jupiter showed a bit better than TEC140 with really good, (8P) seeing. On D.S.O. no contest.

    Sol Robbins(astronomical author and distinguished sketcher), from an online thread entitled, ES Firstlight 8inch dob vs. Skywatcher 8inch dob

    Hi all,

    Please find attached a drawing of Jupiter I made last night with my 8 inch Newtonian in my home observatory.  I have to say, I was quite impressed with image quality- the details on the disk were easier to see despite the low altitude of the planet.  The main feature was the dark and turbulent SEB(s), and the start of the STropB in the South Tropical Zone.  The EZ was rather active as was the NEB, the NTB and NNTB contained darker sections.  Io is shown in the drawing and was probably the strongest colour I have ever seen, no doubt this is due to the low altitude.

    Best wishes,

    -Paul

     

    Jupiter_2019-06-29-0012UT_visual_PAbel.png

    Paul G. Abel(author, BBC Sky at Night presenter, Leicester, UK), form an online thread entitled: Jupiter and Io last night.

     

     

    From practical experience I have found optical quality, coating quality, proper baffling and eyepiece used more important to contrast than CO size once its below around 30%. Why small APO’s out perform slightly larger obstructed scopes is usually NOT due to being un obstructed but optical quality, mechanical quality and other factors. A smaller CO is nice, but can limit your fully illuminated field and eyepiece choice. Theory is great, but assumes everything is equal which it seldom is.

    The biggest enemy of contrast is scatter, stray light and optical quality if you have a reasonable size CO.

    Richard Whalen(Florida, USA), from an online thread entitled, Secondary Mirror Obstruction?

    TOMDEY, on 02 Apr 2019 – 9:46 PM, said:

    A six-inch scope with a 30% diameter obstruction resolves far better than an unobstructed five-incher. Just generate the non-normalized point-spreads and MTFs to see that in action!

     

    PS: This is why a (good) modest-sized Dobsonian will always blow the socks off a good smaller refractor (any smaller refractor!) for both light-gathering and resolution!

     

    But, gota admit… refractors make fine finder scopes on big Newtonian reflectors…    Tom

    Every time I see yet another thread about secondary mirror sizing and central obstruction (particularly when the MTF graphs start appearing), I say what Tom said above – just use a slightly larger telescope and don’t worry about it.  (And those little refractors do make very nice finder scopes.)

    However, I will also add something else – if you undersize the secondary or size it to only fully illuminate the very center of the field, then you are:

     1) using the part of the secondary that is most likely to have a defect,

     2) using the part of the secondary that might roll off due to cooling,

     3) using the part of the secondary that is often left out of the interferometric analysis, and

     4) forcing yourself into very precise placement of the secondary in order to get something close to a fully and symmetrically illuminated field (in other words, making it very hard on yourself for very little gain).

    My method to size secondaries for most telescopes is simple – add 4″ to half the mirror’s diameter to get the intercept distance.  Then divide by f/#.  Then go up one flat size if the calculation yields a size that is close to a standard flat size.

    So, if I calculate that a 3.1″ or 3.2″ flat is needed, I go to 3.5″.  At 3.4″ – 3.5″, go up to 4.0″.

    The 4″ added to half the mirror’s diameter just allows the use of a filter slide underneath a properly placed SIPS or Paracorr 2.  For a little more breathing room, use 4.5″ in the calculation.

    Try this on various commercial Newtonians and you’ll find that some have secondaries that are too small…..

    Mike Lockwood(premium large aperture mirror maker), from an online thread entitled, Secondary Mirror Obstruction?

    Whew! for my 36-inch F/3.75… that comes out to (18+4)/3.75 = 5.9″ … and mine is 6.25″, with a nice wavefront! And, frankly… even a tad bigger than that might be prudent. I just happened to already have the 6.25 and characterized the wavefront at work… figured a known good one would keep the project hustling along!  I then teased the focuser as close in as possible… reducing that four inches to about three. When I focus my farthest-innie eyepiece… only have a few mm to spare! 

    Tom Dey( retired optical scientist, Springwater, New York, USA), from an online thread entitled, Secondary Mirror Obstruction?

     

    A number of factors are working against reflectors:

    1. Reflectors have central obstructions, which reduce the resolution.There’s also a bit of loss to the spider, which creates diffraction spikes.

    2. Reflectors tend to have problems with temperature differentials within the tube, which creates air currents that distort the image.

    3. Mirrors have more scatter than lenses.

    4. Reflectors have a harder time staying in alignment than refractors.

    5. Reflectors have coma. Refractors have their own problems (chromatic aberration and spherical aberration) but expensive glasses and lens designs can basically eliminate these.

    6. Refractors are usually higher end than reflectors (so, they tend to be higher quality).

    However, you can usually resolve these:

    1, 3. Reflectors scale up far better than refractors, so they can have more aperture, which helps compensate for these problems. Obstruction sizes can be minimized, curved spiders will spread the diffraction spikes around and make them less apparent.

    2. Intelligent fan usage can do a lot for air current formation. Good telescope design can keep cool-down times reasonable and mostly eliminate this issue in use.

    4. It’s pretty easy to get good at reflector collimation. Just keep it collimated.

    5. Coma can be mostly eliminated through use of a paracorr. Or, you can use a longer focal ratio.

    6. There are premium mirror-makers who produce mirrors up to the quality of the best lenses.

    If you resolve these issues, reflectors still do not perform up to the standard of a refractor of the same aperture – but will perform as well as a refractor that is slightly smaller. However, you can get a reflector that is far larger than any refractor you can get. It’s reasonably feasible to get a 12-16″ dobsonian with premium optics and good thermal management, and that will (under good conditions) walk all over any refractor anyone with a normal income will ever be able to afford.

    Mitrovarr(Boise, Idaho, USA), from an online thread entitled; Why are refractors considered to be sharper than reflectors if resolution is a function of the aperture?

    Refractors typically do not suffer from thermals, are typically in excellent collimation, are baffled better, and don’t have a center obstruction.

    The number of reflectors that are miscollimated is astronomical. So overall I think you have a better chance of having a excellent experience with a large APO refractor. BUT, find a 10″ or bigger 1/6th wave or better, perfectly collimated reflector and it will knock your socks off.

    Whichwayisnorth(Southern California, USA), from an online thread entitled; Why are refractors considered to be sharper than reflectors if resolution is a function of the aperture?

    That Dalek, on 03 Mar 2017 – 01:35 AM, said:

    Just a question that came to me. Thanks for any answers!

    Refractors often have better definition, which is the ability to show fine, low-contrast detail.  A reflector solves that problem by being larger, gathering more light and having higher resolution.

    A old rule of thumb is that a 6-inch Newtonian, properly designed and built, will beat a 4-inch refractor.

    Caveman_Astronomer, from an online thread entitled; Why are refractors considered to be sharper than reflectors if resolution is a function of the aperture?

    I will simply say that what we perceive as “sharpness” is not resolution.. A few comments, experiences, thoughts.

    – If I look at 52 Orionis, a 1 arcsecond double star in my 120 mm Orion Eon. It is very close to the Dawes limit so on a perfect night, the disks are overlapping and its difficult split at best. If I point my 10 inch F/5 Dob at 52 Orionis on that same night, and the scope is cooled and of course collimated, 52 Orionis is split wide open. Much smaller disks widely separated.

    In this case, I see 52 Orionis as much sharper in the 10 inch.. But most often, I think the comparisons of both contrast and resolution are made in relative terms, at a 0.5 mm what do I see?

    – Looking at the Globular M79 in Lepus is a 6 inch refractor versus my 22 inch Dob, few would perceive that the refractor was sharper.. M79 in the 22 inch looks about like M13 in a 10 inch. M79 in a 6 inch looks, well we know what it looks like..

    – Reflectors are fininky to the uniniated.. They require care and attention.. Collimation and thermal management are important..

    It always seems there comparisons are made between some sort of ideal refractor and the average faster Newt. An 120 mm F/5 achromats versus a 130 F/5 Newtonian.. I think most would (f)ind the Newtonian sharper…

    Jon Isaac(San Diego, California, USA), from an online thread entitled; Why are refractors considered to be sharper than reflectors if resolution is a function of the aperture?

    mogur, on 04 Mar 2017 – 02:19 AM, said:

     

    dugpatrick, on 03 Mar 2017 – 01:53 AM, said:

    All good points.  But, yes, resolution is better with larger aperture.  An 8″ newt will have better resolution than a 4″ APO. And better CA.

     

    Doug

    Only if it’s PERFECTLY collimated! (a rare find) And I’ll take a little CA over loss of contrast because of a spider vane and secondary obstruction.

     

    Perfect collimation of reflectors is not hard to obtain, with the right tools (Glatter laser + TuBlug or Catseye cheshire + autocollimator).   But not every reflector owner is so demanding of collimation, nor willing to spend for the top-level tools that reliably produce perfect collimation.  OTOH, others of us are a bit happily OCD about collimating our reflectors.

    FirstSight(Raleigh, North Carolina, USA), from an online thread entitled; Why are refractors considered to be sharper than reflectors if resolution is a function of the aperture?

    Apo refractors exist in a sweet spot where their unobstructed aperture and single-pass light path tends to produce better images than similar aperture reflectors in the same seeing conditions. Most amateurs view with seeing conditions that put anything larger than about ten inches at a disadvantage because the scope resolution is limited by the seeing, not the aperture. With steady seeing and constant temperatures (e.g. Florida) reflectors can do just as well as apo refractors for visual use.

    GJJim, from an online thread entitled; Why are refractors considered to be sharper than reflectors if resolution is a function of the aperture?

    mogur, on 04 Mar 2017 – 02:19 AM, said:

     

    dugpatrick, on 03 Mar 2017 – 01:53 AM, said:

    All good points.  But, yes, resolution is better with larger aperture.  An 8″ newt will have better resolution than a 4″ APO. And better CA.

    Only if it’s PERFECTLY collimated! (a rare find) And I’ll take a little CA over loss of contrast because of a spider vane and secondary obstruction.

     

    The difference in inherent resolution between an 8-inch scope and a 4-inch scope is so vast that the Newt would have to have disastrously poor optics or be really badly collimated to flunk this particular test.

    Operating at the magnifications useable in a 4-inch APO, the loss of contrast due to the 8-inch Newt’s central obstruction is barely detectable.

    Tony Flanders(Former Sky&Telescope Editor, Cambridge, MA, USA), from an online thread entitled; Why are refractors considered to be sharper than reflectors if resolution is a function of the aperture?

    osted 04 March 2017 – 08:23 AM

    Mitrovarr, on 04 Mar 2017 – 04:26 AM, said:

     

    grif 678, on 04 Mar 2017 – 03:43 AM, said:

    In all my old books, way back before APO’s and SCT’s. the rule of thumb seemed to be, in all instances, that a 3 inch refractor was about equal to a 6 inch reflector. I often wondered why, since a 6 inch mirror had so much more area than a 3 inch lens, but I guess the focal length and secondary obstruction had something to do with it.

    I wonder if that figure was due to worse coatings back in the day. I really wouldn’t expect a modern 3″ refractor (any kind) to beat a 6″ of equivalent quality. Even back in the day, I’m not sure. I have a really good long 3″ achromat and a good 6″ homemade (not by me) dob, both are at least 30 years old, and the dob totally destroys the refractor on planetary detail.

    I think one only has to setup and RV-6 alongside a 3 inch F/16 achromat to see that even 50 years ago,  a 6 inch Newtonian was far more capable than a 3 inch refractor… 

    Been there,  done that,  know the result,  don’t need to do it again.. 

    Jon Isaac(San Diego, California, USA), from an online thread entitled; Why are refractors considered to be sharper than reflectors if resolution is a function of the aperture?

    We can confidently say that a well-made 4-inch refractor can do better than a well-made 4-inch reflector, but the issue gets a little murkier when we start looking for a refractor that is a serious competitor for a well-made 12-inch Newtonian, for example, or even for a well-made 8-inch Newtonian.

    Caveman_Astronomer, from an online thread entitled; Why are refractors considered to be sharper than reflectors if resolution is a function of the aperture?

    So there I am with my 120 mm F/7.5 Orion Eon with the FLP-53 doublet that cost me $1200 used and next to it is a 10 inch F/5 Dob that cost me $240 used.

    Splitting doubles, the 10 inch does the number on the refractor, viewing Mars, the 10 inch does the number on the refractor. This should be no surprise. This does require an operator who knows how to clean a mirror, the collimate a scope, to cool a scope.. And it does require decent seeing..

    Inch for inch, there is nothing as potent as a small refractor.. Dollar for dollar, pound for pound, reflectors offer more planetary contrast, will split tighter doubles..

    Jon Isaac(San Diego, California, USA), from an online thread entitled; Why are refractors considered to be sharper than reflectors if resolution is a function of the aperture?

    Refractors are great. Too bad they are all so small in aperture

    Caveman_Astronomer, from an online thread entitled; Why are refractors considered to be sharper than reflectors if resolution is a function of the aperture?

    caveman_astronomer, on 04 Mar 2017 – 1:40 PM, said:

     

    Cpk133, on 04 Mar 2017 – 1:25 PM, said:

    God, or natural selection, depending on your persuasion, seems to favor refractive optics for wide fields, low maintenance, and the sharpest views per mm of aperture.

    What kind of refractor should I buy that would compete with a 12-inch Newtonian?

     

    This 10″ refractor should do the trick.  http://www.cloudynig…nch-tec-at-wsp/

     

    $50 000 + $15 000 for the mount and $8 000 for the tripod.

     

    Cotts(Madoc, Ontario, Canada), from an online thread entitled; Why are refractors considered to be sharper than reflectors if resolution is a function of the aperture?

    russell23, on 04 Mar 2017 – 3:24 PM, said:

     

    treadmarks, on 04 Mar 2017 – 3:14 PM, said:

    People often say refractor images are more “aesthetically pleasing” (sharper?) even if they don’t show more detail. Aside from the quality issues mentioned, I’m thinking it’s also because smaller telescopes are more resistant to bad seeing. My understanding of the theory is that larger telescopes can have better contrast through brute-force, by having more clear aperture. So it’s not the contrast giving refractors more aesthetic images, it’s their smallness and the fact that refractors take the most advantage of that smallness.

    That certainly could be part of it.  Another factor for me is the simplicity of the observing.  I am able to sit at the back end of the scope and sight along the tube to locate objects or stars for star hopping.  The viewing is always comfortable like that and sighting along the tube with your eye next to the eyepiece is not as easy with a newt.

     

    Like I said – I’m not ant-Newtonian.  I might even look to pick up a large dob when I retire.  But for now I’m very happy with what I have.

    I think a Newtonian is actually easier to point.  Imagine an object 75 degrees elevation.  With a refractor,  it is very awkward to position my head to look along the tube or through a red Dot or Telrad finder.  With a Newtonian,  the focuser and finders are at the sky end of the scope,  I just lean over,  glance through the Telrad,  point the scope, comfortable and effective. 

    Jon Isaac(San Diego, California, USA) form an online thread entitled, Why are refractors considered to be sharper than reflectors if resolution is a function of the aperture?

    Quote

    I don’t even use a finderscope with my refractor.    The first thing I did when I bought the 120ED was sell the finderscope.     My widest TFOV eyepiece serves as my finderscope.  Sometimes that is the 40mm Pentax XL (2.8 deg TFOV).  Sometimes that is the 32mm plossl, 32mm Brandon or 28mm Pentax XL (1.6 deg TFOV).  Or if I’m feeling really interested in a challenge I might even use the 12mm XF or 9mm Morpheus (0.77 deg TFOV) and go sweeping for the target.    I sight along the tube to locate stars to starhop from or a lot of times I just point the OTA right to the location of the target.   I find it remarkably efficient.

    Like I said,  I can make it work..  You talk about spending more time observing the object,  working a list of double stars at 60 degree elevation with a 50 mm RACI finder is much more efficient than awkwardly sighting along the tube,  and then using a wide field eyepiece to locate the object.. 

    With my short focal length refractors,  I generally just shoot from the hip..  But there is no doubt,  the Dob  with the Telrad and RACI finder is much better for easily finding more challenging objects. 

    Jon Isaac(San Diego, California, USA) form an online thread entitled, Why are refractors considered to be sharper than reflectors if resolution is a function of the aperture?

     

    Richard Whalen, on 04 Mar 2017 – 6:14 PM, said:

    Planets, brighter DSO objects or the moon in high contrast the refractor can be the best choice.

    After more than 50 years observing, I find the aesthetics of the view more important than the brightness. Also part of the experience for me is also sitting out under the stars on a perfect night and seeing the silhouette of that long white tube against the background of a sky full of stars. Somehow it’s how it should be, and all is right in my world.

    I know what you mean; there’s something about those grand old 6-inch achromats on their massive German equatorial mounts that sends a chill down the spine. The views are incredibly clean, and the scopes are big enough to yield some very detailed views of the planets — but just barely big enough.

    The fact remains that a 12-inch Dob is far cheaper and more portable than a long-focus 6-inch achromat. And while its aesthetics may be lacking, on a good night it can deliver far more planetary detail than said achromat.

    Tony Flanders(Cambridge, MA, USA), form an online thread entitled, Why are refractors considered to be sharper than reflectors if resolution is a function of the aperture?

    mlbex, on 17 Mar 2017 – 6:34 PM, said:

    When is the last time a major observatory built a refractor? As far as I know, the largest refractor still in use is the 36-incher on Mt Hamilton, built in the 1880s (according to Wikipedia)! It’s still a fine telescope, but there’s a reason observatories are building reflectors. Perhaps they scale better. That wouldn’t really be a problem with everyday astronomers.

    Yes, reflectors scale vastly better, for several different reasons. To be precise: false color scales linearly with aperture, large lenses are hard to support, and the glass for a lens has to be perfect throughout its thickness rather than just at the surface. And this is indeed an issue for everyday backyard astronomers.

    Refractors pretty much rule supreme in apertures smaller than 90 mm. There are some pretty good 76-mm Newtonians on the market, but they’re only marginally cheaper than equivalent reflectors, and they have a number of disadvantages. So they appeal mainly to people who are really hard-up for money. There are also a handful of Mak-Cas scopes in apertures of 60 or 70 mm, but since the main benefit of that design is small physical size, and 60- or 70-mm refractors are already quite small, the tiny Mak-Cas’s aren’t very popular.

    Refractors are also quite competitive in apertures from 90 to 125 mm. But toward the top of that range, the disadvantages of the design are beginning to kick in big-time. At 125 mm, either you end up with a short-focus achromat with tons of false color, or a long-focus achromat that’s really unwieldy and hard to mount, or an apochromat that costs a minor fortune.

    At 150 mm, refractors are really a stretch. Very few people can afford apochromats in this size, and with achromats you typically end up with both lots of false color and an unwieldy size. There are nonetheless some people who love 150-mm achromats because of their low light scatter, but that’s truly the end of the line. Refractors bigger than 150 mm (6 inches) are rare indeed in the amateur world.

    With reflective designs, by contrast, you’re just getting started at 150 mm. That’s considered quite small for a Newtonian, and not quite there for an SCT. Eight-inch Newts are really cheap and effective, especially on Dobsonian mounts, and eight inches is the standard size for SCTs.

    In the modern world of amateur astronomy, where deep-sky objects are the most popular targets, even 8 inches isn’t much. That’s barely enough to resolve most globular clusters or see the spiral arms of the biggest and brightest galaxies. So while refractors certainly have their place for viewing wide fields, for viewing the planets in less-than-perfect seeing, and above all for photography, the fact that they scale up poorly definitely limits their popularity among amateur astronomers.

    Tony Flanders(Cambridge, MA, USA), form an online thread entitled, Why are refractors considered to be sharper than reflectors if resolution is a function of the aperture?

    Newtonians, provide a natural, simple viewing position for the eyepiece at all apertures. Refractors and Cassegrains require tall tripods and star diagonals. We’re not going to make the artificial distinction and comparison between 90mm refractors and 90mm reflectors or between any other refractors and reflectors that happen to have nominally matching apertures.

    Caveman_Astronomer, from an online thread entitled; Why are refractors considered to be sharper than reflectors if resolution is a function of the aperture?

    Redbetter, on 20 Mar 2017 – 10:30 AM, said:

     

    caveman_astronomer, on 18 Mar 2017 – 1:17 PM, said:

     

    Newtonians, provide a natural, simple viewing position for the eyepiece at all apertures.

     

    An equatorial Newtonian appears to have some rather unnatural eyepiece positions depending on the declination of the target and the position on relative to the meridian.

    No, I’d say that if an equatorial-mounted Newt has rotating rings, it’s always easy to find some comfortable viewing position regardless of where the scope is pointing.

    However, I don’t really agree that Newts provide the best viewing position regardless of aperture. I do agree that alt-az mounted Newts (including Dobs) have the best ergonomics of all designs up to a focal length of around 1,500 mm, maybe even to 2,000 mm. But beyond that, they start to require increasingly tall ladders, which begin to get genuinely dangerous and/or scary around 3,000 mm. In those focal lengths, I think that Cassegrain designs are quite clearly superior, due to the fact that you’re observing from the bottom of the tube and the fulcrum is closer to the back than the front.

    Refractors certainly have the worst ergonomics, at least in focal lengths above 1,000 mm. They really have the worst of all possible worlds: bottom viewing, long tube, fulcrum far from the eyepiece, viewing angle exacerbates variation in head height rather than counteracting it as with a Newtonian.

    Tony Flanders(Cambridge, MA, USA), form an online thread entitled, Why are refractors considered to be sharper than reflectors if resolution is a function of the aperture?

    I’ve just recently got myself my first refractor (a 120mm f5 achro) after having used an 8″ f6 dob my whole life. I was actually quite surprised to find the ergonomics much worse and I have had to constantly adjust the height of the tripod to find a good position. Despite this, observing close to the horizon for long periods of time seems quite awkward for the neck.

    Olle Erikkson(Sweden), form an online thread entitled, Why are refractors considered to be sharper than reflectors if resolution is a function of the aperture?

    300x in an 8 inch is a 0.7 mm exit pupil or about 37.5x /inch. Even my 70 year old eyes can view the planets at magnification levels and more, provided the seeing supports it.

    I consider 300 x fine for an 8 inch..

    Jon Isaac(San Diego, California, USA),from an online thread entitled, 8″ F/5 Newt planetary and coma

     

     

    Richard Whalen, on 09 Jul 2019 – 04:34 AM, said:

    How much magnification you can use depends on your optical quality, seeing and your eyesight and aperture. With my 8″ scope I am often around 350x to 450x on Jupiter, and 525x on Saturn. Sometimes higher when conditions are perfect.

     

    My rule of thumb is 43x the aperture in inches on a very good night with decent optics, higher for very good or excellent optics. Also much depends on which planet you are observing.

    Richard, I am usually between 333x and 400x on Jupiter in my 8″, as well, at 0.6mm and 0.5mm exit pupil. I find 333x (~40x per inch) power to be the most productive and my rule of thumb, as well. At 400x, Jupiter is still workable, but it’s beginning to dim a little. I was looking at Oval BA the other night, it was easy at 333x. I could see it at 400x, but not as easily.  And I am fairly sure at 500x it would have been even more difficult. I accidentally pulled out the wrong eyepiece and hit 1200x once (0.16mm exit pupil!). Not much to see up that high. I guess my optics are not that good. smile.gif

    I get that the quality of our optics produce nice sharp and high contrast images at high power, after all it’s the same quality image we see at less magnification where (lack of) aberration is apparent in terms of resolution and contrast. But I am always interested in the mechanism of how high quality optics can afford higher magnifications at vanishingly small exit pupils, say a bit smaller than 0.5mm, without excessive image dimming. At some point we begin to lose visual sensitivity and, thus, lose the image itself as the eye is working at a very small relative aperture (less than about 0.5mm f/60).

    Getting closer to 600x on Jupiter, IME, is unworkable (or at least not as productive as a bit less magnification) in any 8″ aperture even in good seeing. I mean, we can still see some detail up that high, I saw some detail at 1200x, too. Just not much detail was perceived by the eye, even though we are viewing the same fine afocal image we observed at 400x and less. At some point, it becomes less about the optics and more about the exit pupil and, I suspect, throughput as well.

    For example, Jove is fine on both 6″ Mak and 8″ Newt at 0.6mm exit pupil, (240x and 333x, respectively). But, at 0.5mm exit pupil, the Mak image is unworkable while the Newt image still had some legs. I suspect this has something to do with the throughput of each scope, not so much about their respective quality or difference in aperture. Of course the 8″ image is brighter, thus affording higher magnification than the 6″. They are pretty close to the same level of quality, not premium but pretty good and roughly the same obstruction. Both were thermally stable and well collimated. Seeing varied from above average to very good in both over time.  (I agree with you in another thread when you talked about stray light control and mechanics, too.) 

    But, when I hear folks talk about quality optics affording higher magnification, I am always reminded of the small exit pupil involved and how quality might over come the inverse square law and our own personal level of acuity (as a variable). Unless you or they mean magnification higher than say 1mm exit pupil when poor optics start to become visually and visibly soft, while better optics retain their fine imaging properties until the image surface brightness is no longer supported at smaller exit pupils. Sometimes when folks talk about ludicrous magnification in any scope, and especially in premium scopes, I wish they’d elaborate on what they saw up that high. Tight double stars or a bright planetary nebula? 

    I just do not understand how quality affords higher magnification to smaller than 0.5mm exit pupils (very small relative apertures) and well above the magnification where poor image quality becomes apparent. 

    Asbytec(Pampanga, Philippines), from an online thread entitled, 8″ F/5 Newt planetary and coma

    After 500x the image starts to get too dim in a 8″. This is where a 14.5″ shows it’s stuff at 1000x on Jupiter.

    Chas, I know you have great seeing. My seeing is pretty much the same during our dry season monsoon. So, yea, we’re operating at higher magnifications, generally, and on Jupiter, specifically, as well as other objects. I guess that is the crux of my question. Assuming descent optics in both, the 14.5′ at 1000x is about the same as an 8″ near 550x. In my experience with an 8″, the image is less productive starting about 400x and above. Others may vary somewhat, of course.

    Unless the optics are truly better in the 14.5″ in appropriately good seeing. Then my question is why can the higher quality, larger 14.5″ aperture show it’s stuff at much higher magnification than roughly the equivelent of an 8″ showing it’s stuff at 400x? The equivelent magnification in the 14.5″ would be about 750x, but why does quality allow it to show it’s stuff at 1000x (equivelent of 550x in the 8″)? I’d love to know what can be seen up that high because, my thoughts are, the 14.5″ image is dimming, too, for the same reason the 8″ is already dimming at 400x and higher.

    I’ve seen the Jovian image at 500x and 600x in the 8″, but I would not call it really a great image (on the eye, anyway). There is some detail to be seen, still, and the limb appears to be as sharp. But, a lot of the lower contrast detail is becoming or is already difficult to see. Bright high contrast stuff like double stars are no problem, but Jove is a different animal. It cannot be pushed to ludicrous magnifications, but if it can and optics are the reason, then my question is why and what is seen up that high. A sharp limb, a few belts, the moons, and maybe the GRS?

    Asbytec(Pampanga, Philippines), from an online thread entitled, 8″ F/5 Newt planetary and coma

    My lifetime-best view of Jupiter in the 12.5″ was at 456x (36.5x/inch), and we could see a knotty white swirl in the salmon colored (then, now it’s more orange) GRS.

    The whole disc looked like the surface of an orb, not a flat disc, and the colors were amazing–ochers, pale ivory, bluish tints, grey-greens, reds, whites, blacks, greys, etc.

    It was a technicolor image, and super-sharp–sharp enough we could see the shadows of projections on the cloud banks below. And an 18 element stack of lenses in the focuser.

    Spectacular seeing conditions, obviously.

    On other nights of superb seeing, I’ve gone as high as 986x (79x/inch), just to see if it could be done, but I haven’t been able to see what I saw that night.

    The moral of the story is that it is not only optical quality, but seeing that determines how high a magnification we can use.

    In absolutely perfect seeing, I’ve used a superb 7″ scope at 160x/inch and the image was OK. I just couldn’t see anything in that scope at 160x/inch

    that I couldn’t also see at 100x/inch, though the image of Saturn at 1123x was incredibly large.

    But even after all the crazy high powers, give me 400-500x with spectacular seeing, and I can see details on Ganymede and Neptune. 1000x isn’t really necessary.

    It’s all about the seeing.

    Starman1(Los Angeles, California, USA), from an online thread entitled, 8″ F/5 Newt planetary and coma

     

    The short answer is that a good Premium telescope will probably perform noticeably better than an average cheap mass-marketed one. Somewhere between better and way better. But that’s actually a statistical statement. Occasionally a too-good-performing cheap one somehow slips through their QC system… and occasionally a Premium scope will be deficient. The Premium scope is almost always worth the Premium price differential. That is to say — if you don’t want to mess around — just buy the better scope and enjoy it! 

    Tom Dey(Springwater, New York, USA), from an online thread entitled: Premium 1/10PV 8″ Newtonian vs mass market 8″ Newtonian.

    I owned a Synta 8”f6 Dob along with a custom 8”f6 Dob with a Zambuto mirror for several years. The differences in the views were subtle, requiring side-by-side viewing on rare nights of excellent seeing to confirm. On the other hand, the improvements in the views offered by two inches additional inches of inexpensive aperture were obvious.

    If an 8” scope is the largest you want to handle, and you want improved views, premium 8” optics will provide a marginal improvement at about 10x the cost. An inexpensive 10” scope will cost about 2x and the improvements in its views will be obvious. However, premium scopes usually come with premium mechanics in addition to premium optics, and the mechanical improvements are usually obvious under all circumstances.

    So, my preferred approach these days is to empirically determine the largest scope that I am comfortable using at an observing site, and then upgrade or replace its optics and mechanics as much as my budget allows

    Gwlee, from an online thread entitled: Premium 1/10PV 8″ Newtonian vs mass market 8″ Newtonian.

    Make sure that “1/10 wave Peak-to-Valley” rating is on the wavefront, not the mirror surface. Also, make sure the seller has a good reputation.

    I went a different route, and had my first Synta 8″ F/6 mirror re-ground by a respected glass-pusher, as its initial figure was quite poor. To fill in the gap while this was in process, I purchased a second Synta 8″ F/6 (yeah, seems like a stupid idea, but the second one was reasonably good). The total cost was lower than buying a complete specialist-built scope, but of course I had to do a little work myself.

    I’ve decided to hold onto both scopes for now. I’ve set up the one with the great mirror using a better mirror cell, low-profile focuser, and smaller secondary, optimizing it for high magnifications, while the second scope is for lower mags, with a larger fully-illuminated field.

    Like you, an 8″ Newtonian is at my limit for weight and size.

    Hoawardcano(Olathe, Kansas, USA), from an online thread entitled: Premium 1/10PV 8″ Newtonian vs mass market 8″ Newtonian.

    Starlease, on 19 Jul 2019 – 7:44 PM, said:

    Put a Zambuto mirror in my 10″ dob and it outperformed my 14″ claimed 1/8 wave dob for planetary details seen. Little tiny details on Mars seen in 10″ were invisible in 14″.

    Your 14″ dob at 1/8 wave is about 1/4 wave at the wavefront – just diffraction limited. It’s possible in extremely good seeing that your 10″ would show more detail, but on an average night I doubt it, unless there are other issues that you haven’t thought about like cooldown, collimation, mounting of optical components, or maybe the claim of diffraction limited of the 14″ isn’t true.

    People are always looking for fairy dust they can sprinkle into their telescopes to make them defy the laws of physics. Someone let me know if it works. smile.gif

    Nirvanix(Medicine Hat, Alberta, Canada), from an online thread entitled: Premium 1/10PV 8″ Newtonian vs mass market 8″ Newtonian.

    Replacing the 2ndry will probably be the best bet

    but you should learn how to star test 

    https://youtu.be/QxUQJjjsdW4

    Pinbout(Montclair, New Jersey, USA), from an online thread entitled: Premium 1/10PV 8″ Newtonian vs mass market 8″ Newtonian.

    Although I didn’t do it with 8″, but with 10″, I think the mirror exchange was a large improvement for visual observations. Views through my GSO 10″ were good, but star tests have shown some astigmatism. Following the advice on this forum, I exchanged the secondary mirror for Antares, but the astigmatism was still there. So, I decided to exchange the primary for the 1/10 pv. The difference is considerable. With GSO mirror, the views were very good, now they are great. I can see many more crispy details on Jupiter, Saturn, Mars or the Moon. Things that were ‘soft’ before are sharper now. And it happens even on the nights with poorer seeing, I just have to wait for the moment in between smile.gif

    For low-power, wide-field DS objects, probably there is no difference, but color: GSO coating produced a greenish touch, OOUK makes it more white/ flat.

    With GSO mirror, I often used the aperture mask to see planets sharper. After exchange, in my opinion the aperture mask only makes things dimmer and less sharp, so I guess the scatter light before was bigger with the standard mirror. 

    Overall, I have learnt the lesson saying that the exchange for a better mirror was worth it, the telescope is used now more often for the sheer joy of visual hunt for details.

    WOJ2007(Tychy, Poland), from an online thread entitled: Premium 1/10PV 8″ Newtonian vs mass market 8″ Newtonian.

    After owning a really fine 8” CZ mirror for several years I am always impressed by the views when the mirrors are properly collimated and when the primary mirror has reached thermal equilibrium. Is it better than a mass market 8”? I can’t say because I have no way to compare. It’s also really light for the given aperture (better construction/thinner mirror) without giving up stability.

    What I can say about my premium reflector is that the mechanicals beat the pants off my venerable, but flawed 10”. The focuser, balance, bearing smoothness, primary mirror cell, secondary mirror holder are superior in every way. The entire tube is flocked and the cradle design allows the tube to be easily turned and/or moved north south. My definition of a premium scope (which includes the mirror) is one that both offers expected mirror performance while the structure disappears as one uses it. A premium scope is more than a premium mirror and a premium mirror will fall short of full potential if one has to battle with the other parts.

    Chesterguy(Stillwater, Oklahoma, USA) from an online thread entitled: Premium 1/10PV 8″ Newtonian vs mass market 8″ Newtonian.

    I have two 8ers to compare, one Zambuto 8″ F7, the other a generic “Skywatcher” 8″ F6.

    But the comparison is necessarily through memory . . .

    I visit family a couple of times per year in Australia. Got tired of lugging my C6 and refractor through airports. So last time back I bought an 8″ F6 “Saxon”, which is the same as the Skywatcher 8″ solid tube.

    About a year ago I came across an ad where a guy had the parts for an 8″ F7–the primary being a Zambuto quartz, and the secondary a 1/30 wave Antares. Moonlight single-speed focuser. A solid tube (flocked), and splashed out for an Aurora precision cell. I run it alt-az on a Skytee 2 mount.

    How do they compare?

    I wasn’t expecting miracles with the Saxon. A solid diffraction limited scope was all I was wanting.

    First object was Sirius at high elevation in quite good seeing. Within 2 minutes of setting up the scope on first light I easily split the pup. Done. This is a good scope!

    Star test isn’t perfect (I am no expert on this). My recollection was a brighter ring on the outside on one side or the other of focus. So I’m guessing a less than perfect edge. But it performs very well indeed, and more than met my hopes. I haven’t spend much time on planets with this scope (it does perfectly fine). When down under I’m more interested in the Southern objects–Magellanic clouds put up a ton of detail in this scope.

    But what about that Zambuto? Well, as far as I can tell it is as close to perfect as you can get in an 8″ mirror. Star test looks identical to my eye on either side of focus.

    The mirror is up and ready to go with just a couple minutes of running a fan, and puts up etched views of the planets and moon (it has a very small secondary, and is optimized for planets). A particularly memorable view was of the double double from Mt Pinos (parking lot must be close to 8k ft). Perfect dots and diffraction rings. An observing friend with a lot of experience called it the best view of the double double he’d ever seen.

    But how would this thing compare to a 10″. Well, I think you’ll get a more sharp/contrasty view out of the 8″ premium, but so long as the 10″ is decent, it will resolve more detail, those details will just look a tad softer.

    Areyoukiddingme, from an online thread entitled: Premium 1/10PV 8″ Newtonian vs mass market 8″ Newtonian.

    N3p, on 19 Jul 2019 – 5:57 PM, said:

    Has anyone replaced their regular 8″ Synta Newtonian with a higher quality 8″ Newtonian and how was your experience?

    The key difference I found was as follows.    During critical observation of an object for 5-10 mins, on the couple of times when the atmospheric seeing snapped into focus- lasting 0.5 to 2 seconds- the mass market mirror would give an “ooh nice” response whereas the premium would give a “wow!” response.

    The rest of the time the mirrors were pretty similar.

    On galaxies, the higher strehl mirror gave just enough contrast to pass a threshold where the eye could suddenly detect a dust lane.   The mass market mirror couldn’t reach that threshold.

    Max T, from an online thread entitled, Premium 1/10PV 8″ Newtonian vs mass market 8″ Newtonian.

     

    An inspiring 6″ f/8 ATM build by Matthew Paul, Orange County, New York, USA

    Though I did not  build the scope for imaging, I wanted to share what it is capable of under not so ideal conditions. Very happy with the results of the optics. I need to build a better OTA for it. It’s rather flimsy, the spider is not rigid, the tube flexes, and the focuser is just a plastic rack and pinion, but it works very well for now, and the hard part (the optics) are done. Thank you again to everyone that offered information and assistance as I worked on the mirror.

    MVI_0140-3.jpg

    Matthew Paul(Orange County, New York, USA) quoted here

    Matthew Paul, on 22 Jul 2019 – 3:32 PM, said:

    Though I did not  build the scope for imaging, I wanted to share what it is capable of under not so ideal conditions. Very happy with the results of the optics. I need to build a better OTA for it. It’s rather flimsy, the spider is not rigid, the tube flexes, and the focuser is just a plastic rack and pinion, but it works very well for now, and the hard part (the optics) are done. Thank you again to everyone that offered information and assistance as I worked on the mirror.

    attachicon.gif MVI_0140-3.jpg

    That image ought to give apo owners pause.

    Ed Turco(Lincoln, Rhode Island, USA), from the same thread

    There is real poetic justice in how well a good Newtonian telescope performs.

    JamesMStephens(Hattiesburg, Mississippi, USA), from the same thread.

     

    Hello Marty, I can’t answer all your questions, but I did a shoot out between a 150mm f/8 achor and 200mm f/6 dob on Mars a few years ago at opposition.

    The Dob was much better, I suspect it had more to do with no CA vs the increase in aperture. Mars was smeared with false color rendering very little detail in the views. I sold the Achro because it was too much for me to mount. And in my light polluted sky, I don’t do much low power deep sky.

    I suspect that It would also lose fine detail on Jupiter, but I could not do a side by side compare.

    I have a 6 inch 150 f/5 newt, and it does a good job on Juipter/Saturn. I have not had a shoot out between it and say a 100mm ED, or 120 8.3 acrho for a comparison. As far as personal tastes, my eyes are getting old and are light starved, so usually a brighter less crisp image is preferred over a dimmer crisper one.

    I suspect …. the best scope for viewing the planets at 150mm without going crazy expensive would be the 150 f/8 dob. I’m looking for one right now in the used market. A 120 ed I suspect would do a good job too, but at 4x the price, and a big mount to boot.

    I have an f/5 250 reflector on a dob mount. Best view of Jupiter I have. It does take an hour to cool.

    Vtornado( Northern Illinois, USA), from an online thread entitled: 150mm Instrument for Planets, Which Type?

    I’ve tried them all over the past 40 years.  Best view of planets was through Newts with good mirrors that were properly collimated. Note the underline, because that (particularly the latter) can be an issue with Newts. For something more compact and lightweight a good 6″ Mak is an excellent planetary scope and it won’t cost you an arm and leg.  I just picked up a used Orion 150 Mak and the (visual) images of Jupiter and Saturn are superb. My old 127 Mak is also good but the 150 gives more edge on brightness.

    fcathell(Tucson, Arizona, USA), from an online thread entitled: 150mm Instrument for Planets, Which Type?

    I think a 6” f/8 dob, with top notch optics

    (Spooner) would be a great choice and affordable.

    NHRob, from an online thread entitled: 150mm Instrument for Planets, Which Type?

    6″ mak

    6″ f/8 newt

    4″ fpl-53 double Vixen or triple

    will all give great planet views.

    tomjones, from an online thread entitled: 150mm Instrument for Planets, Which Type?

    tomjones, on 23 Aug 2019 – 01:02 AM, said:

    6″ mak

    6″ f/8 newt

    4″ fpl-53 double Vixen or triple

    will all give great planet views.

    Why add a 4″ into this discussion when it’s an inferior option?  A good 6″ f8 outdoes it.

    azure1961p, from an online thread entitled: 150mm Instrument for Planets, Which Type?

    MalVeauX, on 23 Aug 2019 – 6:33 PM, said:

    So… to add more to this mix…

     

    What would any experienced observers rate a 200mm F6 Quartz reflector to a 150mm F8 ED doublet for planetary views?

     

    Would the extra aperture make enough of a difference?
    Or would the 150mm F8 ED refractor still throw up the better, higher contrast image?

     

    Very best,

    The extra aperture would make enough of a difference if the mirror were superb, the tube material, thermal issues, focuser etc., were all finely tuned and working together. Then there are the ergonomics of viewing position and the question of what type of mount will be used.

    If one were to buy a used 8″ f/6 “classic” EQ mounted Newtonian from a good source, such as someone here on CN, then that would be a very efficient bang for the buck. Especially if the mirror were a known and proven winner. Probably in the Approximately $500 range vs. $2000 for the 150mm f/8 ED.

    “Would the 150mm F8 ED refractor still throw up the better, higher contrast image?” Yes it could, if the 8″ f/6 newt had degraded mirror coating and dust, not collimated perfectly, focuser not smooth, set up on warm surface so that thermals enter the tube and plague the system etc., But in my opinion the Newtonian will win if the details are all taken care of and watched. 

    I wish I could find a local old classic 8″ F/6 EQ mounted Newt to play around with, actually…

    Everlasting Sky( Vancouver, Canada), from an online thread entitled: 150mm Instrument for Planets, Which Type?

    I concur with fcathell, as far as planetary observing with Newtonians when all the necessary conditions are in play. My very best planetary views have been through large truss-tube Dobsonians with premium mirrors, along with large classical Cassegrains, when the seeing has been excellent.

    I also agree with Richard Whalen’s post when the aperture is limited to 6 inches.

    Dave Mitsky(PA, USA), from an online thread entitled: 150mm Instrument for Planets, Which Type?

    Quote

    Even with spot on collimation (Newts, DOBs, Maks, SCT’s, etc.) – you still have a central obstruction vs. none in a refractor and that reduces contrast and resolution…even if just slightly — it does

    It’s worth keeping in mind that the CO does have a small effect on contrast, not on resolution..

    This does mean that a scope without an obstruction, when compared to an other equivalent scope of equal aperture will have reduced fine scale contrast.

    But that’s only if the apertures are identical and the optical quality similar. Otherwise, the contrast is affected by the aperture far more than by a central obstruction. This is why large scopes with COs can provide much greater contrast than a scope without a CO.

    Some years ago I experimented with my 120 Eon by adding a 40% CO, I could see a loss of contrast but it was surprisingly small.

    In this comparison, unless one went with a high quality Newtonians (Spooner) then a $2500 ED Doublet would likely provide better planetary views.

    On the other hand, if weight and length were the guidelines, the a good 8 inch Newt would be hard to beat.

    Jon Isaac( San Diego, California, USA), from an online thread entitled: 150mm Instrument for Planets, Which Type?

    M11Mike, on 24 Aug 2019 – 01:12 AM, said:

    Jon – normally I’m with you 99.9%.  But I have seen numerous times FIRST HAND where a quality 4″ refractor beat out much larger apertures on the planets.  And I don’t think the guys with these scopes didn’t have them properly collimated, etc.  These guys with scopes (like the Meade 10″ SCT) were my observing buddies and they concurred.   They were active seasoned observers like myself.

     

    Mike

     

    Well.. maybe. But you can’t blame that on the CO.  Thermal issues, optical issues, poor seeing..

    Try adding a 35% CO to a 4 inch Refractor and see how much difference it makes.

    Jon Isaac( San Diego, California, USA), from an online thread entitled: 150mm Instrument for Planets, Which Type?

    I’ve had a 6″ F8 newt with 1/8 wave optics and it was excellent for L&P. I’ve got a IM715D mak and the same can be said of it. Big advantage to the mak is in 8 years I’ve never had to collimate it. Either scope would work on my Twilight 2 without a counterweight, I doubt the same could be said of a 6″ refractor. I’ve got an excellent WO ZS110 triplet and it doesn’t outperform my mak or C9.25XLT for L&P unless seeings sub par.

    dscarpa(San Diego, California, USA), from an online thread entitled: 150mm Instrument for Planets, Which Type?

    First Light Report
    Finally, the time had come for first light.  When I put the Glatter laser collimator into the focuser and turned it on to begin aligning the optics, I was stunned to see that the laser beam was hitting the primary mirror inside the circle in the middle of the hotspot.  Despite being driven over 1000 miles and loaded/unloaded twice, the tolerances are tight enough on the telescope. I’ve setup the telescope four different times since – and the initial laser position on the mirror has been inside the 1/4″ (6 mm) hole at the center of the HotSpot every time.  Collimation required less than 1/16 of revolution of any of the knobs on either the secondary or primary mirrors.  I pointed the telescope at the horizon and the zenith.  I moved quickly in altitude and azimuth, and slid the EQ platform through it’s entire range of motion twice.  Collimation didn’t shift.  At all.  
     
    Once the sun dove behind the hills just to the west of the observing site, I uncovered the optics and started the fan in earnest to get the optics cooled to ambient as quickly as possible.  I carry a 10″ rechargeable fan that I used to push air at the front side of the primary mirror, and allowed the built in fan to pull air across the back.  The mirror box is only about 8″ deep in total, so air is able to flow easily around the optics and through the structure to help with temperature changes and cooling. Once full darkness had descended up on the observing site, I removed the front fan, rechecked collimation and got to the business of deep sky observing with the new telescope.  I left the rear fan running at full speed, where it’s just audible as a background noise.  Later I turned this down some just to quiet the fan in the silent nighttime desert. Temperatures dropped 23º F (12º C) over the next 2 hours. The thin optics and open structure of the observing rig did a wonderful job of keeping up with the change.  
     
    When I first began talking with Mike Lockwood about commissioning a fast, thin mirror he told me that I’d likely never seen what a cooled telescope could really do being that my main observing machine has been a 15″ full thickness OMI mirror in a wooden Obsession structure.  I love that telescope, but I learned on this weekend what Mike was talking about.  Conditions that had been blamed for years on poor seeing were not present on this night, even though we all agreed that the seeing wasn’t any better or worse than a typical night at this location.  I spent nearly all of my time over the next few nights observing comfortably with much higher magnifications than I’d ever been able to use previously. 
     
    NGC 5139 – Even though it culminates at just 11º above our southern horizon, Omega Centauri was on the meridian at the end of astronomical twilight, so the three of us agreed that it was the obvious choice for the first target.  We’re all familiar with the views of this object from this site with instruments of all sizes from a 63mm Zeiss refractor to a 20″ f/5 Obsession.  At this low elevation there were some obvious atmospheric artifacts being induced in the image – but we all agreed that this was the finest view we’d had of this granddaddy of globulars.  With a 21mm Ethos I immediately noticed a couple of things.  1 – The telescope maintained perfect balance though it was pointed 10º above the horizon.  When I removed the eyepiece to switch to a lighter one, the telescope didn’t budge.  I’m no designer, but I attribute this to the use of the 30″ altitude bearings and perfectly balanced design.  2 – I was looking at Omega Centauri with 20″ of aperture and a 1.2º true field of view.  The cluster was lost in the middle of a field with all kinds of black space around it. With all that aperture focusing all that globular into the smaller image scale of this wide field, the cluster was astonishingly bright, even by it’s elevated standards.  I hadn’t changed eyepieces or objects yet, and I already knew…..this was going to be a fun telescope.  At 175x in a 10mm Ethos, the cluster is huge, extending nearly to the edges of the field.  What I noticed most was the stars being impossibly tight pinpoints, with black space around them.  The contrast between the globular’s stars and the background sky is the most notable thing from the observation.  
     
    NGC 5128 – This beauty in Centaurus is so close by that you can’t *not* look at it.  Again, the contrast was the most noticeable thing about the observation.  With the 10mm Ethos, the dust lane is sharp and well defined across the face of the galaxy and appears nearly bi-sected with a brighter middle – like looking at the great rift from millions of light years away.  
     
    I wiled away a few hours working through the Virgo cluster high in the west, spent some time counting galaxies in the Coma cluster and then happened upon what has been the most memorable view through this telescope yet.  
     
    M83 – Again, it was the contrast.  An absolute pinpoint of a nucleus with two sharply defined bars extending away for a few arc minutes and then turning sharply to form those beautiful, elegant spiral arms.  What struck me most though was the dark lanes between the arms.  As I continued observing, differences in darkness began to appear in the dark lanes, as well as brighter spots in the spiral arms (HII, OB assocations?).  I didn’t concern myself too much, I just enjoyed the view.  This telescope rocketed this galaxy to a high place on my favorite objects list.  
     
    M57 – I put the telescope on this old standby and basically went camping at the eyepiece.  With an 8mm Ethos, the central star was just there.  It didn’t jump out at you….but it was there and required no effort beyond basic averted vision to see it clearly.  I noted galaxy IC 1296 nearby and that it too was pretty easily seen.  This was where I pushed the magnification.  With a 3.7mm Ethos, the telescope is operating at 475x magnification.  In moments where the seeing settled and the air was steady, the optics weren’t even breaking a sweat.  I was able to observe 4 stars seemingly involved with the nebulosity and the central star was a direct vision object at this magnification.  The interior surfaces of the nebula were clearly mottled and uneven and the entire nebula appeard electric green in the eyepiece.  
     
    Veil Nebula – Always a favorite, our small group spent a solid hour cruising the wisps of this supernova remnant with the telescope.  With an 8mm Ethos and an O-III filter, the nebulosity glows as if backlit by some artificial LED source in the eyepiece.  I traced the entire outline of the nebula noting how the brighter wisps faded into thinner and fainter ones as I followed until they just seemed to disappear.  There’s a patchwork background of nebulosity that I hadn’t noticed before with my 15″ scope.  

    48370580567_bd2a867e80_c.jpg
    Great friend and fellow observer Alan Strauss told me I needed to remain still while observing M101.  Uhhhhh….okay!  That won’t be hard.  I could sit here all night.  
     
    …and then came the planets.  I have listened to Mike Lockwood bang the drum about planetary observing with big aperture mirrors for quite awhile now.  Like I told him afterward, consider me one of the converted.  Jupiter at any magnification was an absolute razor blade of sharpness.  Where I was used to seeing equatorial bands, I was now greeted with a swirling mess of sharply defined festoons and bands within bands.  Viewing Jupiter this night was the best views I’ve had that I can ever remember.  My friend Alan commented a few weeks later that the thing that stood out most to him was how sharp the planetary views were through this 20″ scope – he wasn’t expecting it to perform the way that it did.  I concur.  
     
    Just a couple of weeks ago, I set the telescope up again in my light polluted Phoenix backyard to give a quick view of the moon and Jupiter to my lady.  I’ve not been much of a lunar observer since I was a kid, but she is in love with the moon….so, it was time to show her the moon through the new telescope.  She’s not an astronomer by any means….and she’ll be the first to tell you that she doesn’t have those aspirations.  I was stupefied when I looked in the eyepiece.  Stop me if you’ve heard this before – the contrast is unbelievable  – and not just the inky blackness of the crater shadows and brightness of sunlit portions of the lunar surface.  The subtle variations in illumination in the mare and even light differences in color were obvious and a pleasure to behold.  What was supposed to be a quick 20 minute show of the moon and Jupiter turned in to a 2.5 hour session together.  We spent the longest time comparing notes and pointing out features and seeing the smallest details.  The experience has converted me into someone who’s ready to look at the moon again.  I look forward to the intersection of my travel schedule with a break in the Arizona monsoon and a favorable location of the moon so I can repeat the experience.  
     
    Conclusion
    I wanted big aperture with no ladder and absolutely no compromises on the optical and structural quality of the telescope.  It came with an uncompromising price tag too – but I couldn’t be happier with the combination of the Lockwood optics and Osypowski structure & platform.  Mike Lockwood’s reputation for ridiculously fast, sharp optics is well deserved and I’d even dare say still underappreciated.  I selected Mike as my optician for a couple of reasons.  1 – He was great to talk too and has been a great resource for all astronomy/telescope related questions since first talking with him back in December 2017.  2 – A couple of extremely experienced observers that I respect greatly both said the same thing – that the best view that they’d ever had through a telescope had Lockwood optics.  I can now say I wholeheartedly agree with their assessment. 
     
    The Spica Eyes structure built by Tom Osypowski is as nearly perfect as I think it’s possible to build at this point.  It is substantial, stiff and rigid.  It feels like it’s been built for the apocalypse when you put your hands on it.  I chose Tom because of my experience with his EQ platforms and the knowledge that he’s built several telescopes that were both larger *and* faster than this project – so I was confident i would get a telescope that matched my excitement for the EQ platform.  I haven’t been disappointed.  Twice now I’ve done business with Tom.  Both transactions rank as the smoothest, most pleasant money I’ve spent in this pursuit in my lifetime.  I’m proud to be able to say I own one of his telescopes.  
     
    Is the telescope truly perfect?  No.  I have two minor quibbles.

    • There is some stiction in the azimuth axis.  It’s not paralyzing, but it is there.  I got after it when I got back home with some car wax and a buffing cloth which has improved it.  Part of this issue is comparing it to the buttery smooth goodness that is the motion of an Obsession.  I’ve been spoiled by 18 years of use with my 15″ Classic.  
    • The light shroud fits really, really tight.  Getting it pulled down over the structure is a bit of a process.  By process, I mean it takes a couple of minutes.  Once it’s in place – it stays in place and does a wonderful job of blocking stray light but still allowing airflow through it.  So I’ll count my blessings that these are my issues with the telescope.

    I realize it’s been long winded, but there’s little information out there about Spica Eyes scopes.  In fact, there’s really not much beyond a different CN thread that was posted a few years ago about a 24″ scope Tom built.  I submit this review and future experiences and observing reports as part of that body of knowledge.  Tom Osypowski tends to fly under the radar when discussing premium telescope builders, but his handiwork is among the absolute best out there.  He and Mike Lockwood have earned every bit of credit that they get for their skills and contributions to our hobby. 
     
    Mike

    48260256751_f91f413582_c.jpg
    A great shot of the observing site in Portal, Arizona, the 20″ f/3 telescope described here, and the truck/camper that gives me shelter whilst far from civilization for long periods of time.  The light domes are greatly exaggerated in this long exposure.  The one just to the left of the truck is from Lordsburg, NM – 40 miles (64 km) away.  The light dome to the right is from El Paso, TX – 160 miles (255 km) away.

    Mike Wiles( Phoenix, Arizona, USA), from an online thread entitled, First Light Report: 20″ f/3 Spica Eyes/Lockwood Dobsonian

     

    Recently picked up a used (mint condition) Skywatcher 130mm f/5 PDS reflector OTA (Thanks Tyson). This scope is presently discontinued.

    Cosmetics: beautiful black with silver speckles. 9/10

    Inclusions: 8/10 (based on the nice focuser)

    excellent dual rate 2” Crayford focuser with 1.25” adapter

    Vixen style finder mounting shoe

    thin 4 vein spider/ adjustable 2° mirror holder

    oversized 2° mirror (this scope is designed for photography)

    Enhanced 95% coatings on 1° and 2° mirrors

    6×30 straight through finder (mine was upgraded to an Orion 8×40 straight through version)

    2” 28mm LET eyepiece (not included in my used purchase)

    Nice dual hinged mounting rings and Vixen style mounting 7” bar

    Peeves:

    Crayford focuser is non-compression ring

    Crayford focuser has a thread 2” adapter ring using a single metal set screw

    (I removed the ring and drilled/tapped 3 holes a 120° and replaced the metal set screw with 3 nylon ones). I actually prefer this type with nylon screws to a compression ring version.

    the 2”-1.25” eyepiece adapter is also thread-on. You need to unthread the 2” eyepiece adapter ring and the thread the 2”-1.25” one on. Stupid design, just include a regular 2”-1.25” – compression ring or set screw.

    You need a 2” extension tube to reach focus with either 2” or 1.25”, It is not included.

    The included 28mm 2” LET eyepiece is junk (I have tried one). Just include a 1.25” cheapo 25mm Plossl eyepiece.

    I hate straight through finder scopes, replaced mine with an Orion 6×30 RACI version (very light weight but a larger 50mm RACI maybe a better option.

    Optics: 10/10

    easily collimation (it arrived in perfect collimation), 1° mirror is center spotted

    3 spring loaded adjustment knobs with setscrew locks

    95% enhanced 1°/2° mirrors – brighter view than my larger 140mm f/3.64 Comet Catcher

    optical testing – easily 1/8 wave or better

    Observing: I am mainly a Deepsky observer – this a definite RFT

    Fantastic scope, easily punches above a 5” reflector.

    easily takes 160X + (TV 4mm DeLite) , 40x/in- you run out of light grasp

    From low power wide field (3° +) to high power, does it all.

    with high quality eyepieces, I did not need an OCS (Paracorr)

    Some Deep Sky highlights: NELM 5.7 Transparency/Seeing Both 3/5 :

    the Double Cluster – superb, one of my best views ever (mono view)

    NGC 7789 in Cassiopeia (Caroline’s Haystack) – very easy (large smudge with a sprinkling of brighter stars)

    M31 group – all 3 members are easy with direct vision – M31 over 2.25°, M110 diffuse oval

    M33 – large 3/4° smudge

    M81/82 – beautiful contrast in galaxy types

    M51 – Both parts easily visible

    M13 – easily resolved – perfect image (pin **** stars) at 160x

    M27 – amazing with and without filters

    NGC 7000 – fantastic North American shape with NPB filter

    Veil Complex – see my posting in Observing section (Veil in small scopes)

    Future Upgrades:

    I have added a 8” dew-shield

    I will flock the OTA (either the entire tube or opposite the focuser)

    Summary:

    An excellent low priced RFT. Amazing Optics.

    The few minor “peeves” are easily corrected.

    Highly Recommended !!

    vkhastro1(Ontario, Canada), from an online thread entitled, Skywatcher 130f/5PDS-mini review

    Congrats on your new scope! 

    My experience mirrors yours. It is kind of an “unknown” scope, but for my own application it is working better than the Comet Catcher in spite of being smaller and “slower.”

    This scope is kind on the stealth list because when I say I have a 130mm f/5, everyone thinks it is a typical 130mm with small illuminated field and 1.25″ focuser and most do not seem to be aware of the 130 PDS.

    vkhastro1, on 30 Aug 2019 – 5:19 PM, said:

     

    95% enhanced 1°/2° mirrors – brighter view than my larger 140mm f/3.64 Comet Catcher

    optical testing – easily 1/8 wave or better

     

    These are factors that I used in my decision to move from the Comet Catcher to the 130 PDS.  Now my situation was that I am using image intensified eyepieces and I came to feel that the Comet Catcher was punching well below the f/3.6 spec.

    Some of this I thought was maybe due to the need to re-coat the mirrors, but after a painful testing sequence, I determined that the mirrors were OK, but that they were just not transmitting a lot at longer wavelengths (which is important for NV use) and this combined with the losses of the secondary shading and the corrector (which is where perhaps 10% of the loss in near infra red is coming from) meant that the scope simply was not as bright as I thought is should be. I actually think that the entire system transmission (including secondary shading) of the Comet Catcher really does cause it to loose a lot of brightness. I came to feel that the CC was simply much dimmer than it should be for a 140mm f/3.6 scope.

    The other issue I had with the Comet Catcher was the sled focuser and the awkward nature of trying to get it to work with a filter wheel.  The 130 PDS though, with its 2″ focuser with plenty of travel made it easy to use a filter wheel.

    One important point though is that while it is an “Imaging” scope, I don’t think it will fully illuminate an APS-C size sensor.  My NV monocular has an 18mm image circle, and I can see that there is a little illumination falloff at the edge.  Not bad, but it does not appear to have a fully illuminated circle bigger than maybe 12mm. Probably good for an APS-C with some cropping maybe or a 4/3.

    Anyway, as much as I loved the light weight and simplicity of the Comet Catcher, I came to feel that it was much dimmer than the numbers suggested and moved to the 130 PDS and like you, I really feel that it is brighter than the Comet Catcher was. 

    Nice scope.   Not many around as far as I can tell though.  

    130PDS R.jpg

    (Also, the image scale was a plus.  An added bonus was that I had enough focuser travel to use the Barlow lens mounted in one of my filter wheel positions.  This Barlow gives me the ability to bump up the power by about 1.5x just by turning the filter wheel and refocusing.  That is a nice benefit.)

    Good review of what appears to be a relatively unknowns scope.  Hope you are enjoying it!

    Eddgie, from an online thread entitled, Skywatcher 130f/5PDS-mini review

    Very informative comments. I picked up one of these a few weeks ago and use it on a Skywatcher Star Discovery Go To mount that I already had. Quick to set up and cool down, great optics and works really well with my Vixen LVW eyepieces. Nothing to dislike at all.

    brisdob(Brisbane, Australia), from an online thread entitled, Skywatcher 130f/5PDS-mini review

    We are looking into this model and it’s larger models currently.

    Skyward Eyes( Skywatcher USA Vendor), from an online thread entitled, Skywatcher 130f/5PDS-mini review

    For a number of years I had a SpaceProbe 130 ST fitted with a 2 inch Focuser. I normally used it with a Paracorr.. A Paracorr would address the need for an extension tube.

    I have said this before.. a good 130 mm F/5 Newtonian is the closest thing an affordable 4 inch apo Refractor that exists… The 130ST was quite good on planets and doubles as long as it had an hour or so to cool.

    I remember one dark night.. I swapped out my TeleVue NP-101 for the 130 mm F/5  with the Paracorr and 31 mm Nagler..it was scary how good it was.. 

    4920795-SpaceProbe 130ST Starpad.jpg

    Jon Isaac(San Diego, California, USA), from an online thread entitled, Skywatcher 130f/5PDS-mini review

    Ya don’t say; I got me one of them there ‘scopes….ken. I’ve no’ got the 2″ focuser mind, but I dinnae really need it. My bestest grab ‘n’ go ‘scope ever. Eye.

    Mr. Hardglass

    I’m a massive fan of 130 f5’s, even on the ota’s that are limited to 1.25″ ep’s. Very easy to mount scopes, and, when they have decent optics, great all around performers.

    Kerry R.( Mid-west Coast, Michigan, USA), from an online thread entitled, Skywatcher 130f/5PDS-mini review

    I have been using this telescope for around 6 months now on my evolution mount as an eaa platform. For the cost, it makes an excellent alternative to my 925 for wider field views and it can reach zenith with no problems.

    Barkingsteve, from an online thread entitled, Skywatcher 130f/5PDS-mini review

    FINALLY a Dob I really enjoy.

    Been through many different sizes, ranging up to 16 inches.  For me, a 12.5″ Dob is in the goldilocks zone.  Big enough to astound me with the views, but small enough to use every clear night.

    I can’t get enough.  In just 11 weeks of ownership, I’ve used it 42 times, including several trips to dark skies (3.5 hours each way).

    Ryan built a masterpiece.  It’s wonderfully engineered & built.  The telescope is so easy to assemble & disassemble. 

    In use, it is sheer joy.  The movements are silky smooth, requiring little pressure to track an object even at 300x.

    And the views?  Just mind-blowing.  Never thought a reflector could be so sharp and have such stark contrast.  This is the first time I’ve looked through a Zambuto mirror, and the views are as close to a refractor as I’ve ever seen in a mirrored telescope.

    During the last new moon, at extremely dark skies, I pulled the old M13/NGC6207 trick on an observer.  I got her to focus on NGC6207 at 250x.  After several minutes, I asked her to nudge the scope downwards slowly.  A gasp soon followed.  Then the hooting & hollering.  I understood her enthusiasm.  M13 looked photographic.

    Ryan was very gracious throughout the build process.  He promptly & politely answered all my emails, and was very patient, despite my impatience.  He is a master of his craft, and actually converted me from a refractor guy, to someone who can enjoy the night-sky using both types of telescopes.

    Attached Thumbnails

    • CN (2).JPG

    Magnitude 7, from a thread entitled, New Moon Telescope 12.5″ Zambuto refract… er… reflector.

     

    Aperture. Obviously of a decent quality, but aperture is what reveals detail.

    Small telescopes deliver a low magnification sharp looking view, but the fine detail doesnt exist. Its sharp because the magnification is low.

    Double the aperture, double the resolution, simple as that, provided the atmosphere obliges! Which it does more often than some people would maintain.

    Happy Limpet(Southampton, UK), from an online thread entitled, What’s more important.

    If you’re going to use a reflector, mirror quality is very important. I learned this when I had my 2001ish vintage Nova mirror refigured by Mike Lockwood this year. One of the biggest differences I noted was the moon. Before, I could see features on the moon, but the smaller ones could not really be seen, or made sense of, when examined closely. It’s a hard thing to describe, but it was something I noted often, and found frustrating. Detail in the refigured mirror is much clearer in this respect, probably more refractor-like.

    If refractors give a more tightly-controlled image than a similar-quality reflector, then that would be the way to go for lunar.

    I wonder how much the resolution advantage of a large aperture reflector is lost due to diffraction, coma, viewing through a wider expanse of air and a filter, compared to a more modestly sized apo. Maybe you really need to compare apos to apos.

    Mike Tahitub, from an online thread entitled, What’s more important.

    posted 09 October 2019 – 08:16 AM

    MikeTahtib, on 09 Oct 2019 – 10:26 AM, said:

    I wonder how much the resolution advantage of a large aperture reflector is lost due to diffraction, coma, viewing through a wider expanse of air and a filter, compared to a more modestly sized apo.  Maybe you really need to compare apos to apos .

    Diffraction – essentially none.

    Coma – none if using a coma corrector, very little otherwise (depending on f ratio)

    Viewing through a wide expanse of air – none, assuming you know how to get to thermal equilibrium (clue – use fans, its easy)

    A filter? none also

    How much extra money stays in your pocket? Vast.

    Reflectors rule.

    Happy Limpet(Southampton, UK), from an online thread entitled, What’s more important.

    Jon, my experience has been thus – with my Celestron Omni 102mm f/10 (now retired), the moon looked very good, detail was good, contrast as good as could be expected for an achromatic scope, CA was well controlled, but still present. With my SW 120 ED, more detail stood out, I was beginning to see an almost 3D view of things, especially along the terminator. I could also bring the magnification up a bit more than the 102mm, but the seeing conditions had more impact. And CA? What CA?

    With my 10 inch reflector, it is an OMG experience… I had it out Monday night and it quickly reminded me why I love this scope. The detail and contrast that is visible is like being in a Lunar lander on approach… words simply can’t describe the view. The 3D appearance was eye popping. It was a decent night, not great, with the seeing like a 3/5, so at higher mags, there was a bit of waviness at times, but mostly good. Keep in mind that my 10 inch reflector is an ATM scope, so a lot of attention was put into getting top performance.

    This has just served to remind me that a good refractor is no slouch… but has some limitations. A good reflector with some aperture is magical.

    Good hunting!

    Seabee 1, from an online thread entitled, What’s more important.

    My favorite scope for lunar visual is my 8″ f/9. When seeing is good the view is tack sharp. The best view ever was with my 25″ on a extremely steady night. I was hitting 1000x and still had a sharp image.

    Like Jon, no filter.

    Keith Rivich(Cypress, Texas), from an online thread entitled, What’s more important.

     

    More on Double Stars with a  commercial 8″ f/6 Newtonian

    This report is the fifth installment of a series of observational investigations I have made using an 8 inch f/5.9 reflecting telescope.

     

    Check out this link for goals and methods used in this study:

    https://www.cloudyni…-and-monoceros/

    Corona Borealis
    COU 610 Theta (15329+3122) mags 4.27/6.29; pa = 199°; sep = 0.85“, (orbital estimate for 2019.3 is a better fit with historical 4th Int. Cat. data vs last precise from 2016)
    345x, 460x:  single star
    627x:  brightening of diffraction ring that resolves to small dot that is just split 20% of time; at resolution limit and very challenging; re-measure of separation desired

    Draco
    HU 149 (15246+5413) mags 7.48/7.62; pa = 270°; sep = 0.665“, (2016, last precise; solid data)
    345x:  moves past elongated to notched (snowman) 30% of time
    460x:  at resolved/split border as seeing allows; both stars are light yellow-orange
    627x:  resolution aided with orange filter under excellent seeing conditions; a bit above resolution limit

    Image below is from 2017.444

    STF 2054AB (16238+6142) mags 6.15/7.09; pa = 351°; sep = 0.943“, (2017, last precise; solid data)
    345x:  easily seen as split 100% of time to two white stars of slightly dissimilar magnitude; above resolution limit
    image below is from 2019.455

     

    STF 2218 (17403+6341) mags 7.08/8.37; pa = 308°; sep = 1.476“, (2015.5, Gaia DR2; solid data)
    345x:  split 100% of time to two whitish stars; averted vision aids visualization of the fainter secondary; above limit

    STF 2403 (18443+6103) mags 6.25/8.35; pa = 278°; sep = 1.061“,  (last precise, 2011; solid data)
    345x:  seen as just split 50% of the time; both stars are yellow with the much smaller secondary sitting a bit past the first diffraction ring; above resolution limit
    There may be a number of observations for this one as it is part of the Sissy Haas Uneven Double Project

    STT 369 (19071+7204) mags 7.82/7.91; pa = 8°; sep = 0.684“, (2015.5, Gaia DR2; solid data)
    345x:  just split when seeing allows; both stars are yellowish-orange with secondary a bit smaller
    460x:  easier to see as split; above resolution limit

    MLR 12 (18293+8235) mags 8.90/9.12; pa = 222°; sep = 0.689“, (2008, last precise; data is old)
    345x/averted vision:  mostly pointy
    460x/averted vision:  much smaller secondary seen as resolved only 20% of the time—very difficult; right at resolution limit; separation re-measure needed

    STT 312AB Eta (16240+6131) mags 2.80/8.20; pa = 143°; sep = 4.676“,  (2015.5, Gaia DR2; solid data)
    345x:  secondary is a tiny speck of light well separated from the primary; held steadily in view on nights of better seeing; above resolution limit

    Hercules
    COU 107 (16169+1948) mags 9.02/9.61; pa = 113°; sep = 0.609“, (2009, speckle; data is old, scant)
    345x:  very faint; merely a bit elongated; below resolution limit; important data point to assess faintness factor; re-measure of separation needed

    STF 2107AB (16518+2840) mags 6.90/8.50; pa = 107°; sep = 1.443“,  (2015.5, Gaia DR2; solid data)
    345x:  easily split; both stars are whitish and the secondary is quite a bit smaller than the primary (but not tiny); above resolution limit

    A 350 (16540+2906) mags 9.47/9.61; pa = 144°; sep = 0.630“, (2019.542, own measure; considered solid because in line with 4th Int. Cat. trend)
    345x:  possibly pointy (not resolved); faint!
    460x/averted vision:  barely resolved when seeing permits with the secondary appearing just a bit smaller versus the primary; at resolution limit; important data point to set faintness factor

    Image below is from 2019.542

    BU 627A, BC (16492+4559) mags 4.84/8.45; pa = 40°; sep = 2.116“, (orbital estimate for 2019.4; system is opening; value is in line with last precise [2.06”] and Gaia DR2 [2.105”])
    345x:  easily split; both stars are white and secondary is quite small; above resolution limit
    Inverted image shown below is from 2017.501

    BU 812 (16071+1654) mags 9.06/9.36; pa = 96°; sep = 0.73“, (2011, last precise; data may be incongruent with historical 4th Int. Cat. values)
    345x/averted vision:  image moves past elongated to notched about 40% of time showing two similar magnitude, faint stars; a re-measure of both separation and delta mag is desired; considered a bit above resolution limit

    A 228 (17063+2631) mags 9.31/9.88; pa = 13°; sep = 0.658“, (2019.553, own measure; system is opening)
    345x/averted vision:  image is at the elongated/resolved border; discs are tiny—very faint!
    460x/averted vision:  resolved about 50% of the time; a bit above the resolution limit
    Note:  listed magnitudes are from Hipparcos, not Tycho
    Image below is from 2019.533

    HDS 2446 (17177+3717) mags 4.62/8.53; pa = 143°; sep = 0.918“, (2010, last precise; solid data)
    460x:  split ~100% of time on night of very good seeing; adding an orange filter to the optical train causes the secondary to nearly disappear which explains the exceptional difficulty experienced imaging this object; above resolution limit

    STF 2315AB (18250+2724) mags 6.57/7.77; pa = 115°; sep = 0.600“, (orbital estimate for 2019.4; solid data)
    345x:  merely a bit oblong
    460x:  moves past elongated to a snowman shape about 30% of the time—stars clearly of dissimilar magnitude; on border of resolved but never actually seen as resolved; appears to be just below resolution limit
    Inverted image shown below is from 2017.512

    BU 641 (18218+2130) mags 7.03/8.66; pa = 341°; sep = 0.78“, (2015, last precise; solid data)
    345x:  moves past pointy to resolved about 10% of the time; secondary is much smaller
    460x:  seen as split when seeing allows image to sharpen (~30% of time); above resolution limit

    STF 2339AB, CD (18338+1744) mags 7.45/8.67; pa = 277°; sep = 1.482“, (2018, last precise; likely solid data)
    345x:  easily split to show fine magnitude contrast pair with primary seen as white and secondary as light orange; above resolution limit
    460x/averted vision:  secondary [CD] now appears elongated—it has a rho value of 0.492” and is known as WAK 21CD—a very nice bonus!

    A 238 (18114+2519) mags 8.59/9.55; pa = 74°; sep = 0.632“, (2019.548, own measure)
    345x:  persistently pointy
    460x/averted vision:  moves past elongated to resolved 20% of time; secondary is tiny; at resolution limit
    Image shown below is from 2019.548

    A 2093 (18054+1624) mags 9.09/9.85; pa = 226°; sep = 0.642“,  (2008, last precise; data is old but considered solid)
    460x:  very faint, elongated rod that presents as resolved perhaps 5% of the time; at or slightly below resolution limit

    TDT 1042 (18461+1328) mags 8.85/9.65; pa = 274°; sep = 0.7“,  (2009, last precise; data is old, not solid)
    345x:  merely point; stars are faint
    460x:  sharpens to resolved from a rod shape about 10% of time; at resolution limit; re-measure of separation needed

    STF 2084 Zeta (16413+3136) mags 2.95/5.40; pa = 112°; sep = 1.373“,  (grade 1 orbital estimate for 2019.211)
    345x:  light orange secondary just touching bright white primary—beautiful!  Above resolution limit
    Image shown below is from 2019.452

    STF 2203 (17412+4139) mags 7.72/7.81; pa = 293°; sep = 0.757“, (2015.5, Gaia DR2; solid data)
    345x:  just split to two white stars—not difficult; above resolution limit

    Libra
    STF 3090AB (15087-0059) mags 9.09/9.34; pa = 287°; sep = 0.627“, (2017, last precise; little corroboration from 4th Int Cat.)
    460x:  elongated only; never resolved
    627x/averted vision:  never moved past elongated; below resolution limit; not sure why this object is so difficult—a re-measure of separation is desired

    I1269AB (15249-2322) mags 8.73/8.84; pa = 199°; sep = 0.654“, (2015.5, Gaia DR2; solid data)
    345x/averted vision (best conditions):  resolved to two white stars of very similar magnitude about 30% of the time; at or slightly above resolution limit; important data point to establish minimum rho value for calculator

    BU 225BC (14255-1958) mags 7.16/8.37; pa = 91°; sep = 1.285“, (2015.5, Gaia DR2; solid data)
    345x:  split 100% of time showing the primary as white and the secondary as light yellow and smaller; above resolution limit; a beautiful triple with the AB pair designated SHJ 179 or H N 80

    HJ 4756 (15197-2416) mags 7.90/8.27; pa = 242°; sep = 0.574“, (2015.5, Gaia DR2; solid data)
    345x/averted vision:  moves past elongated to notched 50% of time (never resolved)
    460x:  resolved 50% of time; discs are very small and appear similar in magnitude; a bit above resolution limit; important data point to establish minimum rho value for calculator

    A 81 (15089-0635) mags 9.43/9.76; pa = 41°; sep = 0.68“, (2005, last precise; data is old and scant)
    345x/averted vision:  rod only; stars are very faint
    460x/averted vision:  moves past elongated to resolved at most 5% of the time; below resolution limit; re-measure of separation desired

    Lyra
    HU 1300 (19202+3411) mags 8.92/9.56; pa = 184°; sep = 0.74“, (2015, last precise; data is solid)
    345x/averted vision:  mostly a single star, but possibly rod-shaped; faint!
    460x:  at most rod-shaped (never resolved); below resolution limit which makes this object an outlier—further investigation warranted

    A 703 (19072+4451) mags 9.01/9.28; pa = 189°; sep = 0.57“, (2010, last precise; likely solid data)
    as yet unobserved; important data point to establish faintness factor for resolution calculator

    BU 648AB (18570+3254) mags 5.34/7.96; pa = 243°; sep = 1.303“, (grade 2 orbital estimate for 2019.3)
    460x:  small brightening apart from the primary that sharpens to a small disc that is seen as split 50% of the time
    627x:  split 100% of time; secondary is much smaller, both stars appear white; above resolution limit

    Have you observed or imaged any of these double stars?  I would love to hear of your endeavors with these objects.  Are there other, similarly challenging objects in these constellations that I have missed?  Let me know.

    Nucleophile(Austin, Texas, USA), from an online thread entitled; 8 Inch Reflector Investigations. Part V: Corona Borealis, Draco, Hercules, Libra, and Lyra.

    Hu149_DRA.jpg

    STF 2054AB

     

    STF2054AB_DRA.jpg

    A350_HER.jpg

    STF2315AB_HER.jpg

    STF 2084 Zeta

     

    STF2084_Zeta_HER.jpg

    STF 2084 Zeta

     

    STF2084_Zeta_HER.jpg

    A238_HER.jpg

    Nucleophile(Austin, Texas, USA), from an online thread entitled; 8 Inch Reflector Investigations. Part V: Corona Borealis, Draco, Hercules, Libra, and Lyra.

    Excellent as always Mark!

    Here are some of my observations from your list, plus a few others you might try:

    Cou 610 AB: 8″ 667x: Notched/snowman at best moments.  B definitely fainter and almost blue.  Very faintly split, looks like a blue appendage.  20″ diffraction is too messy.

    STF 2107 AB: !! 12.5” This was a CDSA plot find, didn’t expect it to be special.  Yellow and orange pair, very close ~1.5″, 1 delta mag.  Very pretty.

    STF 2315 AB: 12.5” 553x.  Near contact / overlapping disks, 0.5 delta mag.

    BU 641 AB: 12.5” 553x. !! Extraordinary!  Moderately bright A and much fainter B, <1″ separation.  Seeing needs to still.

    STF 2339 AB-CD: 20”: 533x: White and dull white B. Close but well separated, ~1″ [AB-CD seen. AB is Hu 322 1 delta mag 0.2″, not noticed]

    STF 3090 AB: 12.5” Notched to hairline split at the best moments. Faint pair, tough. Seeing not good enough to go above 553x. [AB seen; AC fainter and wider.]

    BU 648: 8″ 333x: 3 delta mag, at first diffraction, needed critical focus and seeing.

    OTHERS:

    Met 9: 8″ 205x nothing.  8″ 410x suspect elongation.  667x see a fleeting, bluish point just outside of first diffraction ring.  A is light yellow orange and bright; 2 delta mag. to B.  A feels elongated / egg shaped.  At 20″ and 667x the seeing is too messy though there is a knot in the diffraction where I had noticed the point with 8″.  Strong feeling A is elongated.
    12h 54m 39.98s +22° 06′ 28.8″ P.A. 51 sep 1.7 mag 5.70,7.77 Sp F8V+M2-3V dist. 33.85 pc (110.42 l.y.)

    STF 1967 = Gamma CrB: Definite mis-shape, oval to egg.  8″ 667x.
    15h 42m 44.57s +26° 17′ 44.3″ P.A. 104.6 sep 0.22 mag 4.04,5.60 Sp B9V+A3V dist. 44.78 pc (146.07 l.y.)

    STF 2289: Just split in 20″ at 205x, but flaring. 333x had messy diffraction. 8″ mask at 333x gave clean disks, split, ~0.7″. Dull yellow and yellow-red colors.

    18h 10m 08.69s +16° 28′ 35.0″ P.A. 215.3 sep 1.24 mag 6.65,7.21 Sp A0V+G0III dist. 263.85 pc (860.68 l.y.)

    STT 359: !! Kissing 8″ 333x, hairline split 667x. 20″ too diffracted. Near equal white A and bluish white B.
    18h 35m 30.40s +23° 36′ 19.9″ P.A. 3.7 sep 0.75 mag 6.35,6.62 Sp G9III-IV dist. 144.3 pc (470.71 l.y.)

    A 260 AB: 20″ 667x: At 8″, small and faint suspected split at 333x: 8″ 667x stars are hazy. At 20″ 667x got a clean wide split two hard paints of stars.
    18h 57m 34.07s +32° 09′ 20.2″ P.A. 244 sep 0.8 mag 9.17,9.60 Sp A0

    STF 2422: 8″ 333x: Excellent hairline split at 333x with 8” mask. Near equal white stars. Picked them out in a crowded field, suspected elongation right away, split with seeing as I centered it in eyepiece, and from then it was a steady split
    18h 57m 07.83s +26° 05′ 45.1″ P.A. 68 sep 0.8 mag 7.93,8.25 Sp A2IV dist. 156.25 pc (509.69 l.y.)

    AGC 9 AB = Sulafat: 8” 533x: B star immediately picked out of A’s glow like a piece of debris suspended in the explosion, or a planet hanging in the halo.
    18h 58m 56.62s +32° 41′ 22.4″ P.A. 307 sep 13.5 mag 3.24,12.10 Sp B9III dist. 190.11 pc (620.14 l.y.)

    HO 92 AB 20″ 667x: ! Beautifully well split, had an instant of perfect images. White pair near equal.
    19h 00m 59.89s +32° 33′ 11.6″ P.A. 40 sep 1.3 mag 10.59,10.85

    COU 1156 AB 20″ 667x: ! Near qual small and at best moments a clean split, still, just nice points. great star.
    19h 00m 34.25s +33° 01′ 24.8″ P.A. 111 sep 0.7 mag 11.14,11.25

    STF 2461 AB = 17 Lyr: 20″ 667x: ! Huge delta mag. B is obvious in 20″, though A’s diffraction was horrible. Used 8” mask to clean it up but the B star momentarily disappeared, though I could eventually pull it back out with seeing and critical focus. 4 delta mag.
    19h 07m 25.58s +32° 30′ 06.2″ P.A. 281 sep 3.2 mag 5.26,9.10 Sp F0V dist. 41.58 pc (135.63 l.y.)

    mccarthymark(San Francisco, California, USA), from an online thread entitled; 8 Inch Reflector Investigations. Part V: Corona Borealis, Draco, Hercules, Libra, and Lyra.

    I like using my 105mm APO on double stars over my larger scopes just because it gives nicer images even when the seeing is below average.  I still get nice round stars but the whole image kind of bounces almost like my clock drive is making it bump up and down a little.

    An 8″ scope will be affected 4 times as much as a 4″ on the same night, so in this case aperture doesn’t rule in below average seeing.

    If I am going specifically after doubles, I tend towards my 10 inch Dob rather than any of my refractors.  One reason is for it to perform it’s rock solid best, I need to set out up before sunset and run the fans for considerably more than an hour.

    If the seeing is on the good side and I started with a 4 or 5 inch, I’m stuck.  

    For closer doubles, maybe 1.4″ or closer, the 10 inch provides wider splits under most circumstances because it’s Airy disk is so much smaller. A 1.14″ double is a Dawes limit split in a 4 inch, in the 10 inch it’s a wide split and I’m not fighting both the large Airy disk and the seeing.

    I’m not sure about your factor of 4 in terms of the effect on the image. I am not looking so much for a pretty image, I’m looking for closer splits. Antares is usually a challenging split in a 4 or 5 inch but last year I made the split in my 22 inch with Antares quite low on the horizon, no way in a small scope.

    It wasn’t pretty but it was very wide, bright and apparent. It made me realize just how small the airy disks are in a scope that size.

    With any scope but a larger scope in particular, the outer seeing aberrated region can as an extended object while it surrounds the region where the airy disk is brighter. Cranking up the magnification can increase the contrast by dimming that outer region.

    Jon Isaac( San Diego, California, USA), from an online thread entitled Effects of Bad Seeing: Double Stars

    This was my second dark site session with my new telescope.

    A week before, I had to cut the session short as humidity became unbearable – spider and shroud started dripping.
    I want to share my impressions of this device now that I had a full session.

     

    Logistics first.
    This is not a small scope so I got a folding aluminum ramps for loading it. This way, I can load the scope alone and it is faster than loading my SW 12″ collapsible.
    just need to make sure that mirror box is tilted a bit so the bearing will not hit the car ceiling.

    FHh9hdim.jpg

    Truss and shroud are light and have plenty of room.
    For a 20″ monster, the process of loading is easy enough.
    If not totally lazy or must, the scope can be loaded/unloaded without ramps.

    The road to the dark site is about 2.5 hours drive. I have been making this trip every month for over a year now and love the drive.
    re4jgQFl.jpg jELqQBTl.jpg

    I was the first on site, about an hour before dark.
    Unloading was simple enough and once everything was out of the car, I went to assemble the scope

    Assembly is quick, Truss to mirror box, fasten the bolts, UTA on Truss, fasten the bolts and then the shroud.
    This takes few minutes and is easy, just as Ryan show in his Youtube channel.

    lIjKInHl.jpg 60bzIWYl.jpg

    For collimation I use the Farpoint 2″ collimation kit – laser and cheshire.
    Even after 2.5 hour drive, last part of it is off-road, collimation did not drifted by much.

    The entire process of assembly + collimation takes about ~20 minutes.
    With camp set – tent, table chairs, I still had time to dress for the cold before total darkness.

    I was lucky to see the gathering of Venus, Moon and Jupiter with Saturn watching from above.

    That was an amazing sight!
    wrqf0Bjl.jpg

     

    Observations:

    First I revisit the Vail nebula.
    Eyepiece – Nagler 31mm filtered with O-III
    Started with the Western part of the nebula from the tip through Cy52 to its bottom part. The amount of details was insane.
    The Eestern part as equally stunning.

    The central part of the nebula was nicely visible.

    Tonight’s plan was to go through objects in Cassiopeia, Perseus, Andromeda, Orion and Ursa Major.

    Double cluster fits nicely into the FOV of the Nagler 31mm. Very sharp image.
    Raising magnification a bit, still could see both clusters within view.
    Next came the Owl cluster, M103, NGC 663 and more.
    Pacman nebula was also nicely visible, I will have to revisit this object to figure out more details.

    I did a quick detour to view M15. This cluster is magnificent! raised magnification to 135 and the cluster could be resolved nicely.
    With magnification of over x200 which is reserved for such objects, I could easily distinguish stars almost to the core.

    Andromeda Galaxy showed two dust lanes, one very distinct and the other is fainter. I never saw so many details in the arms before.
    Both companions – M110 and M32 also fit the FOV.

    Pinwheel Galaxy, another showpiece object also provided much details.

    In Orion, I saw the bubble nebula for the first time.
    M42 is majestic as ever, all the details are just fantastic, the nebula is closing full circle, wings full of details. With filters, different details emerge.

    The 20″ collects so much light that even a cellphone camera could yield details (I had to try…)
    Eh3jJUPl.jpg

    Horsehead nebula was not visible when it was 30-40 degrees but when reaching over 50 degrees altitude, provided a lots of details.
    The nebulusity from Alnitak towards HD 37806 was visible with the horse interrupting it like a finger obscuring the view.

    Last area covered was Ursa Major – galaxy hunting.
    Finding galaxies with this huge field of view is fun and easy.

    This session yielded many objects, over 50 were documented, many were not viewed enough and will be revisited to get more details.

    My impressions so far:

    I am very happy with my new telescope.
    The difference in view from my 12″ is everything I expected and more, some objects are actually visible and others show so much more details.

    Views are wide, crisp and sharp, especially when conditions allows.
    Transportability and the ability to handle it by myself is exactly why I opted for NMT in the first place.
    Mechanically this is a wonderfully constructed device. Movement is smooth in both axis but firm enough not to shift when switching eyepieces.
    Balance is the same without eyepiece or with Paracorr-2 + Nagler 31mm. I guess Binoviewer will require some counterweight – Ryan provided rails for counterweight, just in case.
    Collimation lasts in full movement range and during the session – I did not check, but felt no view degradation – will test it on the next session.

    Scope Basking in the morning sun after a long night
    AL5Ge1Al.jpg

    ilan Shapira( Israel), from an online thread entitled; My NMT 20″ f/3.3

    Got back out for an hour or so and tried out my higher powered plossls. Seeing was not great and I’m under white zone skies with limited sky to point at from my driveway but I make it work. I can tell the scope is a bump up from my ST80 with the higher powered eyepieces. To my newb eyes collimation appears good. Stars weren’t exactly pinpricks at high power but they’re round and turn into nice round donuts in and out of focus.

    Took a look at a dimming beetleguese, Uranus with I think a hint at its moons. The Pleiades looked great back down with the 32 plossl.

    M42 looked better than I’d ever seen it at all powers. And it looks spectacular to my eyes with my $13 UHC filter.

    It’s definitely a different experience looking through the eyepiece on this reflector as opposed to my mak and my refractor. Just a bit higher at most views than is perfect viewing on my camp stool, but being able to rotate the tube in the rings brings it to an accessable height.

    (If this post would have been more appropriate in the beginner forum I apologize.)

    Tannhauser Gate, from an online thread entitled, First Light with a cheap 130/650/f/5

    I like 130 mm F/5 Newtonians. If the optics are decent, they’re the closest thing to a budget 4 inch apo you can buy.

    The focuser appears to be a Crayford, that’s a good thing. It looks like a 2 inch Orion focuser,, there’s no adapter?

    Have fun..

    Jon Isaac( San Diego, California, USA), from an online thread entitled, First Light with a cheap 130/650/f/5

    Actually it goes a little deeper than any 4 inch Apo and resolves significantly closer double stars(down to 0.9″) in the hands of experienced observers and good seeing conditiions.

    Mr Hardglass

    That’s a sharp looking scope.,I love my 130.,it’s my most used scope because it puts up great views and is easy to carry out and be viewing.,cheers.

    Clearwaterdave,(Western Maine, USA), from an online thread entitled, First Light with a cheap 130/650/f/5.

     

    Attached Thumbnails

    • 20190327_183143.jpg

     

    Because seeing was good at Christmas I observed Sirius. In 2012 I had great difficulty to see the Pup, but now it was rather easy. I tried to make my pencil sketch as realistic as possible. I added some color in GIMP but I’m not 100% satisfied with the result.

    Which version do you prefer?

    Attached Thumbnails

    • Sirius B afgewerkt grijs 600.png

     

    Attached Thumbnails

    • Sirius B afgewerkt kleur 600.png
    Jef De Wit(Hove, Belgium), from an online thread entitled Sirius B (the Pup)

    I hope to have a 20″SST/Ostahowski f/3.4 in about 12 mo(nths).

    This summer I should have a unique 10″ NMT/Pegasus f/3.4 DOB

    I’ve owned a 12″ Orion dob that has been in pieces as I tried to repair the dead goto system.

    Got an AT130 f/7 that sits too much because, as a DOB lover, I hate equatorial mounts. Has some nice planet views, a super value no question. Just not a KILLER at f/7.

    Been thinking about a Sky-Watcher Skymax 180 f/15 but not many reviews here on CN.

    I’ve reached out to Moonraker about his 150 Mak in development, turns out he’s recovering from some illnesses and the Mak is new for him-gonna be awhile. Just love his work though.

    SO-back to the purpose- what do you suggest for a Planet Killer?

    Stubeeef(North Carolina), from an online thread entitled: Want a Planet killer: suggest some

    Get a cheap 10″ dob.

    Pull the mirror and send it off to a professional mirror refinisher and have them bring it up to a high Strehl level.

    Put a high quality secondary mirror in it.

    Put boundary layer cooling fans on it.

    Even an 8″ f/6 will work well for this, but the 10″ will be better.

    Eddgie, from an online thread entitled: Want a Planet killer: suggest some

    Eddgie, on 17 Jan 2020 – 03:42 AM, said:

    Get a cheap 10″ dob.

     

    Pull the mirror and send it off to a professional mirror refinisher and have them bring it up to a high Strehl level.

     

    Put a high quality secondary mirror in it.

     

    Put boundary layer cooling fans on it.

     

    Even an 8″ f/6 will work well for this, but the 10″ will be better.

     

     

    This ^

    SteveG( Seattle, Washington, USA), from an online thread entitled: Want a Planet killer: suggest some

    The slower the scope, the better. I had a Discovery 10 F5.6 that gave great planetary views, but it couldn’t compete with my 8” F9 when it came to high power views. With 3.5 mm and 5mm eyepieces, I can comfortably view objects at high power all night long. And not once have I ever observed a planet with my 8” and thought, the image isn’t bright enough. Barlows are useful with fast scopes, but a 2x barlow will not perform nearly as well as a scope with twice the F ratio.

    Galicapernistein, from an online thread entitled: Want a Planet killer: suggest some

    bobhen, on 17 Jan 2020 – 1:40 PM, said:

    It’s all about the quality of the primary. Whether its F5 or F8 doesn’t matter. If the mirror is 1/10 wave it is 1/10 wave.

     

     

    I think closer to 1/8 limit

    But it has to be real. Regardless of the manufacturer and its advertising promotion.

    a  I, from an online thread entitled: Want a Planet killer: suggest some

    I would think a 20″ Ostahowski f/3.4 would be a fine instrument for planetary observation once cooled and well collimated… 20″ of well figured aperture would pretty much kill anything you throw at it.

    Volvonium(Long Beach, California, USA), from an online thread entitled: Want a Planet killer: suggest some

    Not really sure what to suggest but my 25″ kicks butt on the moon and planets. Barring going for such a big scope my 8″ f/9 Parks newt on a platform is a close second.

    Keith Rivich(Cypress, Texas, USA), from an online thread entitled: Want a Planet killer: suggest some

    I have an f/4.5 16” Ostahowski mirror, and also an 8” f/7 by Steve Lee. Both appear excellent mirrors but the 16” slam dunks the 8” on everything. As it should. Every time I think of building a planet killer…like, say, a 10” f/7 or whatever, I remind myself I already have one.

    Oberon(Hunter Valley, NSW, Australia), from an online thread entitled, Want a Planet killer: suggest some

    I have a 6-inch F/8 that is a planet killer for a small telescope, but the 8-inch SCT, 10-inch F/4.5 an 15-inch F/4.5 Dobs also do very well on the planets too when the seeing is good. I spent many hours looking at Mars, Jupiter and Saturn with my reflecting telescopes, and imaging them with the 8-inch SCT. The best views though came with my Dobs though, especially the 15-inch. That said, the 6-inch is no slouch and has excellent optics, the primary mirror was made by Meade back in the 70’s. The 10-inch also has a Terry Ostahowski mirror, and the 15-inch has a primary mirror made by Optic Wave Labs.

    Achernar(Alabama, USA), from an online thread entitled, Want a Planet killer: suggest some

    A well figured 10″ as has been mentioned. Some of my best views of Mars were with a 10 f/5.4. Saw dark volcanoes on Mars years ago with 8″ f/7. Mars was high up, seeing was spectacular and scope was working well at 600x. My eyes were a bit better, too.

    Mike Spooner

    Any well built Newt is a brute for planets in my super steady seeing. Fast or slow is fine. Old school 8″ F/8 Cave or other makes also make great planet scopes as well as used Starmaster Dobs at around F/4.3.

    CHASLX200(Tampa, Florida, USA), from an online thread entitled, Want a Planet killer: suggest some

    On nights of fair to average seeing, I will be relying on my TSA 120; on good to excellent nights it will be my new-to-me Teeter- Zambuto 10” f/5. It was damaged in shipping is still in limbo awaiting settlement from the shipper.

    Skyranger(Prescott, Arizona, USA), from an online thread entitled, Want a Planet killer: suggest some

    Custom designed Newton:

    Obstruction less than 20% = planet killer or APO killer

    Cameras for planets: ASI / QHY – 290 / 224 = 6 – 7 mm diagonal.

     

    Newton 12″ F/5.3  (300×1600)
    Primary Mirror: 303 mm
    Secondary Mirror: 50 mm
    Obstruction: 16.5% (Obstruction surface: 2.72%)
    Illuminated diagonal: approx 9-10 mm

     

    Newton 12″ F/5  (300×1500)
    Primary Mirror: 303 mm
    Secondary Mirror: 50 mm
    Obstruction: 16.5% (Obstruction surface: 2.72%)
    Illuminated diagonal: approx 7-8 mm

     

    Newton 10″ F/6.4 (250×1600)

    Primary Mirror: 254 mm
    Secondary Mirror: 40 mm
    Obstruction: 15.7% (Obstruction surface: 2.48%)
    Illuminated diagonal: approx 10-11 mm

     

    Newton 10″ F/6 (250×1500)
    Primary Mirror: 254 mm
    Secondary Mirror: 40 mm
    Obstruction: 15.7% (Obstruction surface: 2.48%)
    Illuminated diagonal: approx 8-9 mm

     

    Newton 10″ F/5 (250×1250)
    Primary Mirror: 254 mm
    Secondary Mirror: 45 mm
    Obstruction: 17.7% (Obstruction surface: 3.14%)
    Illuminated diagonal: approx 7-8 mm

     

    You can do the calculations on this website:

     

    https://stellafane.o…b/newt-web.html

    cabfl, from an online thread entitled, Want a Planet killer: suggest some

    My 8″ f/8. Royce primary, Protostar quartz secondary. After midnight, when the seeing settles and the scope temperature has fully equalized.

    K15CAW, from an online thread entitled, Want a Planet killer: suggest some

    I had a 6” F8 Discovery dob that had an excellent mirror. But my SW 100 ED was close enough that I sold the dob for the convenience of the refractor. But going from a 6” F8 to an 8” F8 or 9 dob puts you into an entirely different league. I would put my 8” F9 against any 5” APO refractor. That said, I still want a 5” APO refractor.

    Galicapernsitein, from an online thread entitled, Want a Planet killer: suggest some

    obhen, on 17 Jan 2020 – 7:38 PM, said:

    No place in the United Sates will a 20-inch telescope ever resolve to its full potential.

     

    On few nights and in the best locations like south FL. a 12 to 16-inch will have a chance but in most locations just getting sub arcsecond seeing is rare. And not only do you need that seeing but the planets need to be high or at zenith or the seeing will be compromised even more.

     

    For example…
    “At the William Herschel Telescope site in the Canary Islands, even this superb viewing location (second best in the northern Hemisphere) has many nights of relatively poor seeing: the distribution is positively skewed, and at this excellent site, a 10-inch telescope will be seeing limited on 9 out of 10 nights.”

     

    Bob

     

    That’s really not the question. A large scope maybe seeing limited but still outperform a smaller scope. 

     

    The Dawes limit and the Rayleigh criterion are not the appropriate measures to determine the resolution/ seeing limits. 

     

    In 1 arc-second seeing, a 10 inch will be seeing limited but dramatically out perform a 5 inch. 

     

    Think about airy disk diameters and overlapping disks.. 

     

    This my planet killer..

     

    IMG_18102019_213052_(1080_x_1080_pixel).jpg
    13.1 inch F/5.5 with a Royce mirror.  
    The 16 inch and the 22 inch could be but are permanently located in the high desert where the seeing is not as good as it is near the coast.
    Jon Isaac(SanDiego, California, USA), from an online thread entitled, Want a Planet killer: suggest some

    The best planet killer is the atmosphere.

    A scope also needs to be thermally stable and well collimated, as well. There are better scopes out there, of course, so get one. But prepping a scope for planet killing is probably the most important factor outside of seeing conditions and recognizing planetary detail when we see it.

    Asbytec(Pampanga, PI), from an online thread entitled, Want a Planet killer: suggest some

    I’d say something in the 10-12″ f/5.5 + range with good optics and proper cooling.

    jakecru(Nevada, USA), from an online thread entitled, Want a Planet killer: suggest some

    I have an 8″ f/8 dob that is GREAT on the planets. Plus, it’s a lot of fun to use, too. Really has the “OK, so it’s come to this!” feeling when you aim it at anything. Ha! Something to keep in mind is binoviewers are excellent for planetary work, and will the scope/mount handle it. The dob does great with this, too.

    JoshUrban(Indian Head, MD, USA), from an online thread entitled, Want a Planet killer: suggest some

    Bill Jensen, on 19 Jan 2020 – 6:31 PM, said:

    Zambuto has an in stock 8 inch f/7 that is listed on his website. Those don’t come up that often, and may be a nice solution to your planetary viewing desires.

    This 

     

    I have a quartz Zambuto 8″ F/7 on order that should be ready in about a year or so. I would like to find a lightweight scope to house the mirror and then possibly put it on an equatorial platform. 

    starzonesteve(Central Alabama, USA), from an online thread entitled, Want a Planet killer: suggest some

    I got lucky on used parts on AM that included a Zambuto 8″ F7 quartz. It’ll clobber any 6″ refractor on the planets, and is basically up and running in a few minutes as the substrate doesn’t have temperature equilibration issues.

    The 8″ is so good that I’ve decided to replace my 12.5″ F5 Zambuto pyrex with one of his quartz mirrors. I’m hoping it’ll be ready in the summer.

    areyoukiddingme, from an online thread entitled, Want a Planet killer: suggest some

    CHASLX200, on 18 Jan 2020 – 12:11 AM, said:

    Any well built Newt is a brute for planets in my super steady seeing.  Fast or slow is fine.  Old school 8″ F/8 Cave or other makes also make great planet scopes as well as used Starmaster Dobs at around F/4.3.

     

    Most mass made Newts the last 20 years just don’t do it for me.

    +1  I have a 12.5” and an 18” Starmaster, both with Zambuto mirrors, and on the best nights they are planet destroyers.

    turtle86, from an online thread entitled, Want a Planet killer: suggest some

    Galicapernistein, on 21 Jan 2020 – 4:12 PM, said:

    A high F ratio is inherently better for high power views. A slow scope with excellent optics will give better views of planets than a fast scope with equivalent optics. This is a fact that owners of fast scopes need to accept.

    No, it is not a fact, and it is quite wrong, so we will not accept it.  What Jon said above is correct.

    The laws of optics and physics don’t lie – they will give the same view, assuming similar quality eyepieces and equilibration and the the eyepiece is designed for the faster cone, not including some miniscule effects (which are almost always overblown) from a larger secondary in the faster scope.  This is easily overcome by adding a small amount of aperture if one wishes.  Then the slightly larger fast scope wins.

    Let’s not ban certain terms, (i.e. planet killer) let’s educate people about where they came from and why they are misleading or wrong.

    My planetary scope?  My 20″ f/3.0.

    Mike Lockwood,from an online thread entitled, Want a Planet killer; suggest some

    Galicapernistein, on 21 Jan 2020 – 4:45 PM, said:

    So someone starting out in astronomy who wants to see Saturn’s rings should buy a 6 inch F5 because they’re so much more convenient than an F8? I don’t think so.

    Think outside the box.. 

    A 6 inch F/8 is 48 inches long, an 8 inch F/6 is 48 inches long, a 10 inch F/5 is 50 inches long.  They’re the standard dob configurations.. 

     

    I can tell you which one provides the better planetary views… 

    P.S.:  A 6 inch Newtonian is not what I consider a planet killer.  A good scope but not enough aperture.

    Jon Isaac ( SanDiego, California, USA), from an online thread entitled, Want a Planet killer; suggest some

    A slow scope will give better high power views than a fast scope with equivalent optics. It would be nice if we could accept that fact without bringing in these other factors.

     

    I accept that a slow scope with equivalent optics will provide slightly better views than a fast scope.  

    But it would be good if you would accept that those other factors are far more important in providing killer planetary views than the focal ratio.  

    Today, a slow scope that provides the planetary views possible with a large aperture, fast scope is impractical.  

    It is about the views.. 

    Jon Isaac (SanDiego, California, USA), from an online thread entitled, Want a Planet killer; suggest some

    I’ve gotten many extraordinary views of the moon/planets with an optically excellent 10″ f/5 dob. The whole idea of some longish newt or hyper-expensive APO as the only planets killers has one foot in mythology and the other in the grave.

    Largish aperture of high quality is your best bet.

    Nirvanix(Medicine Hat, Canada),  from an online thread entitled, Want a Planet killer; suggest some

    I own a 12.75” F/6 Newtonian with quartz optics that has killer specs and was figured by one of the best mirror makers in the US. On nights of best seeing it kills my TEC200ED, even at f/5.8. But on average nights it is another story entirely.

    Itha(Bend, Oregon, USA), from an online thread entitled, Want a Planet killer; suggest some

    cooke, on 24 Jan 2020 – 3:16 PM, said:

    I’m in the camp of thinking that a planet killer is any scope, regardless of f-ratio, type, or configuration, that has the capability of delivering a killer view of the planets.  As others have said, realizing that view has more involved than just the telescope itself; managing thermal issues, seeing, collimation, viewer experience, etc. all factor into what is seen but reducing the variables to just the telescope itself, it could be anything of sufficient aperture.  I do think that while smaller scopes can give excellent images of the planets for their size, if you don’t have at least 6″ of aperture and preferably 10″ of aperture, you are unable to realize the resolution available on the best of the best seeing nights.  Having said all that, my best views of Jupiter and Saturn ever were with a 18″F3.75 Starmaster.  I think the additional aperture also helps a lot when using high magnification to see the smallest lowest contrast details.  The additional light just helps make the difference even if the larger aperture is seeing limited.

    When I say a high F ratio is better for high power views, I should specify (and I will from now on) that I’m talking about smaller newts. Bigger mirrors can obviously compensate for many issues by sheer resolving power. An 18” F8 might provide better views, but the atmosphere will only allow so much power, and an 18” F8 would require a ladder I wouldn’t want to climb. The bigger exit pupils they provide are a definite improvement over smaller scopes. There’s no arguing that a big, fast newt packs a lot of performance into a relatively small package, and for serious galaxy hunting they can’t be beat. 

    Galicapernistein, from an online thread entitled, Want a Planet killer; suggest some

    scooke, on 24 Jan 2020 – 3:16 PM, said:

    I’m in the camp of thinking that a planet killer is any scope, regardless of f-ratio, type, or configuration, that has the capability of delivering a killer view of the planets.  As others have said, realizing that view has more involved than just the telescope itself; managing thermal issues, seeing, collimation, viewer experience, etc. all factor into what is seen but reducing the variables to just the telescope itself, it could be anything of sufficient aperture.  I do think that while smaller scopes can give excellent images of the planets for their size, if you don’t have at least 6″ of aperture and preferably 10″ of aperture, you are unable to realize the resolution available on the best of the best seeing nights.  Having said all that, my best views of Jupiter and Saturn ever were with a 18″F3.75 Starmaster.  I think the additional aperture also helps a lot when using high magnification to see the smallest lowest contrast details.  The additional light just helps make the difference even if the larger aperture is seeing limited.

    I agree. I have an AP 130 GT, and it’s as good as a 5″ apo can get. It certainly gives great planetary views, but it simply can’t compete with my 18″ Starmaster in terms of resolution, at least where I observe.

    turtle86, from an online thread entitled, Want a Planet killer; suggest some

    If i had to have one last planet scope, it would be a 20″ F/6 Dob.

    CHASLX200(Florida, USA), from an online thread entitled, Want a Planet killer; suggest some

    Newtonians of 8-12.5″ aperture are the most cost effective. I agree with others that perhaps the easiest/cheapest way to a planet killer is to buy a mass-manufactured Dob and have the primary refigured. First, though, you may want to replace the secondary with a high quality mirror from the likes of, say, Antares and see if you are happy. The MTF of any obstructed scope degrades significantly when the diameter of the secondary minor axis exceeds 20% the primary diameter. Thus, you will want such a small secondary, which if you also want a 1 deg or so field with only minor vignetting for DSOs, means f/4.5 or greater. So a 12.5″ with f/4.5 or greater can yield fabulous planetary detail. However, the mirror must be supported properly (check with the freeware program PLOP), the mirror must be allowed to thermally equilibrate (I set mine up at dusk … a fan is a good idea too), and collimation needs to be spot on. Incidentally, mass manufacture SCTs have central obscurations of roughly 35% so planetary contrast aperture-for-aperture is less than with a Newtonian.

    dhfergusson(Pleasanton, California, USA), from an online thread entitled, Want a Planet killer; suggest some

    Personally I use a 200mm F6 Quartz newtonian. I’d love to go bigger, but I also don’t like the idea of ever moving something bigger outside of my observatory, so for non-obs scopes, I keep them portable enough. I also do not like dob-bases due to the materials, I’d want it to be all metal. I’m in Florida. Florida is not friendly to non-metal and I’m not about to baby some cheap particle/ply or whatever cheap dobs are made of, and I’m not spending top dollar on a custom dob. I’d rather have a beefy alt-az and keep it simple and fast with the 8″ for now. Maybe one day I’ll get a metal dob frame and go 16″. But that’s a big maybe.

    MalVeauX(Florida, USA), from an online thread entitled Want a Planet killer; suggest some

    For me the #1 priority is an accurate figure – I’ve been satisfied with Newtonian planetary views from 6″ up to whatever. The primary is the building block at the bottom of the wobbly stack, IMHO. The secondary is next (and often a problem for critical viewing) but smaller sizes can be replaced with less hassle and financial impact than the primary. Most of the remaining problems fall into what I would classify as mechanical/environmental effects, i.e. thermal, collimation, seeing, mounting, etc.

    So pick a size, get the primary right and work from there. My personal opinion concerning f/ratio and secondary size is they can be considered for 6 to 8″ scopes as they are comfortable at f/10 or f/7 (for my height when Dob mounted). For larger scopes I like more comfortable f/ratios. With Paracorrs, modern eyepieces and collimation knowledge available having mitigated some of the old concerns, then we’re back to the quality of the objective – still the base of the wobbly stack for me.

    Mike Spooner, from an online thread entitled Want a Planet killer; suggest some

    Late to the discussion but here are mine, a TEC 200ED and my Parallax/Zambuto 11″ F7.  Rather than compete, they compliment each other.  

    Around here, the seeing rarely supports an 11″ aperture, so the TEC gets used more often.  When the seeing does support a larger aperture, I can get the Newt unbagged, the mount sync’ed and observing in under 10 minutes.  

    For me, planetary viewing demands exceptional optics (and seeing!!) but also a “comfortable’ viewing experience, which, again, for me, means being seated or standing comfortably.  I can do both with both scopes, making long sessions at the eyepiece a pleasure.

    Also for me, I’m just addicted too my bino-viewers, especially for solar system objects.   I just see more and I find the viewing experience much more comfortable than mono-vision, and with my Denk power switch system, I can cycle through three different magnifications instantly.

    For me, an excellent planetary newt has to have the following:

    1. 8″ – 12″ aperture and I prefer F6 or slower focal ratios

    2. Exceptional optics (including the secondary) that are smoooooth, with good coatings.

    3. Central obstruction under 20% (pretty easy to do really, especially in slow scopes)

    4. Excellent build quality which includes easy, precise collimation with the ability to keep collimation when pointed anywhere in the sky over the entire night and an excellent focuser.

    5. An excellent thermal management system, which typically includes a BL fan.

    6. Easy use of bino-viewers

    7. A rotating tube if I use a GEM, for easy, comfortable eyepiece positioning and the ability to put my body down wind of the aperture.

    Can’t wait for Mars this year!

    JeffB, from an online thread entitled Want a Planet killer; suggest some

    First light on my UVenus filter tonight!

    Attached Thumbnails

    Very nice photo. That’s a pretty awesome outcome for first light on any device.Thanks for sharing.

    I hope I’m not out of line in asking: Who is the manufacturer of your 8″ Newt and is the 3100mm your OT focal length?

    jodemur(East Michigan, USA), from an online thread entitled, Venus in UV – 8″ Newt + ASI183MM

    jodemur, on 26 Jan 2020 – 1:16 PM, said:

    Who is the manufacturer of your 8″ Newt and is the 3100mm your OT focal length?

     

    It is a Celestron Starhopper, one of the newer metal tube ones so a standard Synta product. They make pretty solid f/4.9 mirrors all the time so I figure f/6 should be even better. It’s a 1,200mm stock focal length but I measured the pixel width of Venus to calculate that my 2x Orion Shorty Barlow is giving me about 2.6x magnification.

    jragsdale(Idaho, USA), from an online thread entitled, Venus in UV – 8″ Newt + ASI183MM

    ***

    I was going to post in “what did you see with your classic ” but its large enough to be alone

    1 both scopes are in great shape

    2) both scopes mounted on lxd55 mount for better track

    3) seeing was very very good and moon was high up near zenith

    rv6 had 2x barlow

    ed4 some shots with 2x barlow and some not

     

    highfnum(North East, USA), from an online thread entitled, redo classic shootout edmund 4inch vs criterion RV6

    Cool images eh? Like I says in part I, I dinnae trust an over zealous sketcher, ken.

    Mr. Hardglass.

    so both scopes did a great job

    however RV6 does show more detail

    IMHO it looks like I picked up some of rille with ED4 – if correct that’s a new record for me for scope size

    ed4 had more trouble with smaller circular features

    some folks in past have said that a 4 inch refractor has same capability as 6 inch reflector

    if its a good 6 inch – I say no

    highfnum(North East, USA), from an online thread entitled, redo classic shootout edmund 4inch vs criterion RV6

    To be continued…………………..

     

     

     

    Neil English unearths plenty more historical evidence testifying to the prowess of Newtonian reflectors in his large historical work, Chronicling the Golden Age of Astronomy, newly published by Springer-Nature.

     

    De Fideli.

     

    Product Review: Leica Trinovid BCA 8 x 20.

    To establish ‘Limes.’

    Back in the summer of 2019, I got the opportunity to test out a very high quality Swarovski EL Range 10 x 42 owned by a fellow villager named Ian. A keen hunter, he uses this binocular to seek out red deer and estimate their distance using the built-in laser telemetry in the instrument. A few weeks ago, I bumped into Ian in the swing park near my home, where he was looking after his young grandaughter, and we struck up another conversation about binoculars. I was returning from one of my walks,  carrying along my little Zeiss Terra 8 x 25 pocket. He was fascinated with this new instrument, being duly impressed with its razor sharp optics, generous wide field, light-weight ergonomics and decent market value. It was then that I discovered that Ian was also the proud owner of a little Leica Trinovid BCA 8 x 20, which he purchased about two years back for casual sightseeing during his summer vacations in the Scottish northwest. Keen to expand my portfoIio of tested instruments, I asked him if he would be kind enough to let me borrow it  for a wee while to evaluate its optical and mechanical performance. He agreed, but did say that he found the Terra to be very comfortable to use and was even considering acquiring one in the future! Fast forward a couple of weeks and Ian dropped by the Leica binocular at my home so that I could begin some tests, the results of which, I will divulge in this blog.

    Leica is a German optical firm that has established itself as a world-leading manufacturer of high-end cameras, microscopes, camera lenses, binoculars and spotting ‘scopes for the burgeoning sports optics market. Founded in 1869 by Ernst Leitz, at Wetzlar, Germany, where the original factory remained until 1986, after which time production was moved to the town of Solms to the west of Wetzlar.  In 1973, Leitz set up another large factory in  Portugal, where it has remained to this day. With 1800 employees, Leica has an annual turnover of the order of 400 million Euro, and continues to produce state-of-the art optical equipment for private and public institutions(mostly universities and hospitals) the world over.

    The Leica Trinovid line of binoculars has a long history. Leica first began to manufacture high-quality binoculars back in 1907, but the Trinovid line first appeared in 1953. Over the years, Leica has continued to develop their Trinovids, adding new optical technologies to their products where, today, they utilize some of the best glass and optical coatings available.

    First Impressions

    The quality of the device was immediately apparent to me as I prized the 8 x 20 from its somehwat oversized, soft carry case. Weighing in at just 235g, the Leica Trinovid BCA 8 x 20 measures just 9cm long, 6cm wide and 3.5cm deep when folded up. This makes it one of the smallest and most portable binoculars in continuous production today.

    The Leica Trinovid BCA 8 x 20(made in Portugal) folds up into a tiny storage unit just 9cm long and 6cm wide. Note the unusual location of the right eye dioptre setting, which is accessed by turning the objective lens housing.

    The binocular has a very traditional dual-hinge system but maintains a very classic look and feel, with an aluminium frame. Unlike their larger binoculars, the BCAs are described as ‘splashproof’, meaning that they will work fine in rainy conditions but are not hermetically sealed or dry nitrogen purged like the majority of roof prism binoculars today. The all-metal chassis is overlaid by a tough rubber armouring, which greatly improves its grip during field use and affords greater protection against accidental bumping or knocking about.

    The strong and durable rubber armouring overlaying the aluminium chassis of the Leica Trinovid BCA 8 x 20.

    The eyepieces are of exceptionally high quality, being made of metal overlaid by soft rubber cushions for comfortable viewing. They offer just two positions; fuly extended upwards for non-eyeglass wearers(including yours truly) or fully retracted when used with glasses. Eye relief is pretty tight though, at just 14mm, so some eyeglass wearers may struggle seeing the full field. The eyecups hold their position very well and can only be retracted by using considerable downward force. I must say that these are the finest eyepieces I have thus far experienced in my survey of the binocular market. Simply put, they are beautifully designed.

    The beautifully designed eyepieces click rigidly into place.

    Intriguingly, the dioptre setting(+/-3.5) is located on the right objective lens, which turns either clockwise or anti-clockwise. The focus wheel, which appears to be constructed of a hard plastic, is quite small but moves very smoothly with zero backlash. At first, it’s a bit fiddly to use but with a little practice becomes easier to negotiate, though it may present problems to those who wear gloves.  All in all, the binocular is a study in elegant design. Clearly it was created not only to look good but to feel good in active service.

    The Trinovid BCA has a high-quality, somewhat elastic, neckstrap, which is affixed via clips, so can be disengaged from the binocular if so desired. It is comfortable to use. Yet again, an unusual but very nice touch.

    The objective lenses are not very deeply recessed in this model, perhaps because its designers aimed to minimise the length of the instrument. Having more deeply recessed objectives serves a number of useful purposes though, including protection against rain and dust, and serving well as an effective barrier against peripheral glare.

    The objective lenses on the Trinovid are not very deeply recessed.

    Optical Testing

    As is customary for me with the arrival of any new binocular for testing, I began by assessing its performance in suppressing stray artificial light, internal reflections and glare. This is easily done by sharply focusing on a bright internal light source – I use my iphone torch at its brightest setting – in a darkened room and sharply focus on the light. Such tests quickly revealed highly satisfactory results. Stray light was very well controlled and very clean, with only very minor internal reflections and no sign of diffused glare often encountered in lesser models. The main artefact was a reasonably pronounced diffraction spike. Indeed, using two small ‘control’ binoculars; my Zeiss Terra 8 x 25 pocket and my recently acquired Celestron Trailseeker 8 x 32 (both of which exhibit excellent performance in this regard), I judged the Leica 8 x 20 to be as good, if not a little better, than my controls. All of these binoculars employ full, broadband multi-coated optics on all glass surfaces, with prisms that are dielectrically coated for highly efficient light transmission. The results predict that the Leica will perform excellently when pointed at strongly backlit daylight scenes, bright street lights and bright terrestrial targets like the Moon. There is no such thing as absolute perfection though. Such a complex optical device will always betray some degree of imperfection under these very stringent tests. I guess, it just comes with the territory!

    The high quality HDC coating makes for exceptional light transmission.

    In good accord with my flashlight tests, pointing the little Trinovid at a bright sodium street light at night showed no internal reflections, glare and only a very faint diffraction spike that I didn’t find intrusive. These tests were followed up by daylight optical assessments. Looking at tree trunks and branches during bright afternoon conditions showed that this 8 x 20  has excellent optics with a good, wide field of view. The image is tack sharp with a very large sweet spot. There is only slight softening of the images in the outer 10 per cent of the field. Colours are true to form and I detected only the merest trace of chromatic aberration and then only by looking very hard for it(I honestly find this activity rather pointless) on difficult targets. Contrast is exceptional with excellent control of stray light, as judged by imaging targets nearby a setting Sun under hazy sky conditions. There is a normal level of veiling glare which can be removed by blocking the Sun with an outstretched hand. There is also some minor pincushion distortion at the edge of the field but I still judged this to be well above average.

    Excellent coatings make the objectives almost disappear.

    Some readers will be surprised to learn that Leica did not employ any ED elements in the objective lenses of their BCA binoculars, proving once again that such an addition is not at all necessary to create an excellent optic(the Swarovski CL pocket and larger sibling, the CL 8 x 30 Companion are yet other examples). What really matters are well figured glass elements with high-quality anti-reflection coatings. Looking up its specifications online showed that Leica has spared no expense applying their famous(patented) High Durable Coating (HDC). It purports to be abrasion-resistant with enhanced light transmission, and then there’s the solid P40 dielectric phase coating applied to the Schmidt-Pechan roof prisms. What results is a highly efficient light gathering optic; an especially important commodity for tiny binoculars like these.

    The Trinovid certainly delivers optically when the light is good and strong. But it does have some issues which are important to address. Because of its very small size, it’s actually quite challenging to hold steady during field use. It’s small exit pupil (2.5mm) also makes it considerably more difficult to position one’s eyes correctly compared with slightly larger binoculars, such as a good 8 x 25( with a 3.125mm exit pupil). Comparing its ergonomics with my Zeiss Terra 8 x 25 pocket glass showed that the Terra was simply much easier to engage with even though it’s only about 30 per cent heavier(310g). It’s larger frame also gives it the edge in terms of acheiving a good, stable image. This could prove important if the owner intends to use the 8 x 20 BCA for prolonged glassing periods, as the extra effort incurred in accurately positioning one’s eyes over the small exit pupils may induce eye strain with some users, so I think it’s important that people seriously considering this tiny glass try the more popular 8 x 25 units out before making that all-important purchase. Indeed, I believe this point was not lost on Ian when he tried the Terra out in the swing park that afternoon.

    In an ongoing blog on using my 8 x 25 binos, I gave mention to why I think good pocket binoculars are quite expensive in the scheme of things. I attributed this to the extra difficulty in accurately positioning the many optical components stably within a scaled-down structure. The Leica Trinovid BCA 8 x 20 seems to follow this rule of thumb. It is smaller than any 8 x 25 model but is also more expensive(about £350 to £400 UK as opposed to £270 for the Zeiss Terra 8 x 25, for example). But there is surely folly in pursuing this to its logical conclusion. For example, would it be sensible to create an even smaller, state-of-the-art 15mm model say, that can fit on two fingers and cost £500?

    Of course not! That would be daft. It would be too small and fiddly to use and the amount of light it would bring to one’s eyes- even if it were 100 per cent efficient – would severely limit its use. That’s probably why the other premium binocular manufacturers – particularly Zeiss and Swarovski – have discontinued their 8 x 20 models in favour of 8x and 10 x 25mm units. Indeed, all of this has close parallels to the premium, small refractor market, where folk seem to pay exorbitant prices for tiny, albeit perfect, optics. Is that really sensible? Not in my mind – which is why I turned my back on it- but your mileage may vary!

    Assorted notes:

    The Leica Trinovid BCA 8 x 20 has ocular lenses just a little smaller than its objective lenses.

    The instrument comes with a ten year warranty.

    Each Leica binocular comes with a test certificate which claims that it was examined at various times during its manufacture prior to leaving the factory.

    The Leica mini-binocular didn’t appear to come with caps, either for the objectives or eyepieces. It does just fit the small Opticron branded rainguard for compact binos however, which I use with my 8 x 25s.

    It’s hard to find the ‘made in Portugal’ stamp on the Leica. But it is there, stealthily placed under the left barrel of the optic, and only accessed by fully extending the instrument’s IPD to its maximum where you’ll see: Made by Leica Portugal in good light.

    The Opticron-branded rainguard I use for my 8x 25s just fits the smaller leica binocular.

    More info on this package here.

    Comparison with other Premium Pocket Binoculars

    The Leica Trinovid BCA 8 x 20(left)versus with the Zeiss Terra 8 x 25(right). Note the latter’s larger frame and bigger focus wheel.

    I spent a few hours comparing and contrasting the Zeiss Terra ED 8 x 25 and the Leica BCA 8 x 20 during bright sunny conditions(for January) and again under dull overcast conditions, as well as looking for performance differences at dusk, when the light rapidly fails afer sunset.

    Under bright sunny conditions there was not much difference between both binoculars in terms of optical performance(both are excellent in this regard), except that the Zeiss has a noticeably wider field of view(119m compared with 110m@1000m). Because of its larger frame, larger focus wheel and larger exit pupil, the Zeiss proved easier to handle and  easily rendered the more comfortable, immersive view. The weight difference between these instruments is only 75g, so I don’t think many folk would quibble about the increase in bulk mass.

    Under dull overcast conditions, the Zeiss produced a slightly brighter image, which became more and more pronounced as the light began to fade after sunset(around 5pm local time in the last week in January). This ought not surprise anyone, as both binoculars are highly efficient light gatherers and so simple physics dictates that the larger 25mm glass wins.

    Close focus on the Leica was estimated to be about 1.8 metres, significantly longer than the Zeiss Terra at 1.4 metres.

    Comparison under the Stars

    The differences between the 25mm glass and its 20mm counterpart was most pronouced when aimed at the night sky. The larger exit pupil and aperture on the Zeiss Terra pocket allowed me to see significantly fainter stars around Orion’s belt and in the Hyades, compared with the Leica. At first I judged the contrast to be slightly better in the Leica than in the Zeiss but upon reflection, I attribute this to the smaller exit pupil in the former, which naturally generates a darker sky hinterland. The wider field of view in the Zeiss also helps frame objects that little bit better than the Leica. So, for casual stargazing the Zeiss proved noticeably superior to the Leica 8 x 20. I would not really recommend the 8 x 20 for such activities over a larger glass. But neither should anyone expect miracles here. The Leica is designed for daylight use in the main, although one can always enjoy the odd look at the Moon with the 8 x 20 when it is present in the sky.

    Comparisons to a Celestron Trailseeker 8 x 32 Compact Binocular

    How does the Leica Trinovid BCA 8 x 20 compare with a good 8 x 32 compact binocular?

    Comparing a mid-sized, semi-compact binocular like the Celestron Trailseeker 8 x 32 with a diminutive 8 x 20 might seem a little out of place. But I think its inclusion is valid. The Trailseeker is very light; indeed, at just 453g, it ranks as one of the lightest 8 x 32s on the market, but still has many mechanical and optical features that only a few years ago were the preserve of premium binoculars; a magnesium alloy chassis, solid, well-designed metal-under rubberised adjustable eyecups, fully broadband multicoatings, dielectrically coated Bak-4 prisms et cetera.

    Comparing the images served up by both the Celestron and the Leica in bright daylight in the open air, my wife and I both concluded that the Leica has slightly better contrast and sharpness across much of the field than the Celestron 8 x 32. With a small exit pupil of 2.5mm, the best part of your eye lens images the field. Edge of field performance is also significantly better in the Leica. But we also agreed that the Celestron was more comfortable to use, owing to its larger exit pupil (4mm). That said, we also reached the conclusion that the Celestron binocular rendered a slightly brighter image even in good light. But while there are perceptible differences between the two instruments, it must be stressed that these differences are small and subtle. Of course, that conclusion will likely upset a few of the more pestiferous premium bino junkies out there, but it is nonetheless true in our experience. The Celestron held its own very well indeed against the sensibly perfect Leica.

    But there is considerably more to say about the economical Trailseeker. Move from the open air into a heavily canopied forest or copse and the advantages of the larger aperture binocular become much more apparent. Under these conditions, the Celestron fairs a lot better, delivering brighter images and more information to the eye. And as the light diminishes in the late afternoon, the Celestron clearly pulls ahead, as it ought to do, owing to its much greater light gathering power. At dusk, the differences between the two models are literally like night and day. Under these conditions, the 8 x 32 Trailseeker is vastly superior. It doesn’t matter if the optics in the Leica are sensibly perfect when you can’t see those details.

    You see, the little Leica is like an elastic band – stretch it too far and it will break!

    The same was true when pointing both binoculars at the night sky. After struggling to peer through the Leica, the Celestron was pure joy!  Its very efficient light transmission(~ 90 percent) and much wider field of view (7.8 degrees) brings so much more of the Universe to your eye!

    These results helped us both to appreciate just how good the Chinese-made Celestron Trailseeker 8 x 32 really is. At roughly one third of the UK price(recently reduced to half its originanl market value(~£250) for clearance) of the Leica, we’d both say that it delivers 90 per cent of the bright, daytime performance of the Leica and vastly superior low light and night time performance. In many ways, this small and light-weight 8 x 32 is a more versatile performer than the 8 x 20 Leica Trinovid BCA, and those wishing to use their binoculars in more compromised lighting conditions would probably be better served with a good instrument in this size class.

    And I have to ask this question again: is a weight of 453g really anathema to those who want to travel ultra-light?

    nota bene: these comments regarding the Celestron Trailseeker 8 x 32 are also applicable to the previous discussion of my Zeiss Terra pocket glasss, in case you’re wondering.

    These tests affirmed the excellent bang-for-buck the Celestron Trailseeker really represents. Veteran binocular enthusiast and fellow author, Gary Seronik, is dead right in highlighting these recent trends: mass produced, Chinese-derived optics are now coming so awfully close to premium performance-both optically and mechanically – that I would have reservations shelling out much more of my hard-earned cash just to get slightly better optical performance and the right to brag! For these reasons, I’m very pleased with and have no plans to upgrade the 8 x 32 Celestron; it will remain as part of my binocular stable.

    Conclusions

    The Leica Trinovid BCA 8 x 20: lean, mean optical machine.

    The Leica Trinovid BCA 8 x 20 is a beautifully made pocket binocular that exudes elegance in both its solid mechanics and optics. It produces sensibly perfect images, rich in contrast and colour, whilst maintaining a very high degree of sharpness across the entire field. Perhaps uniquely, its advantages and disadvantages both pertain to its very small size.  Provided one knows its limitations though, it ought to provide its owners with many years of service as a high-quality, ultra-portable optical system that can be used for casual glassing at sports events, mountain climbing, hiking, birding, general sight-seeing and even some limited astronomical viewing.

    I found my time with the little Leica binocular to be a particularly enriching experience. While it is expensive, it is certainly money well spent, especially if you plan to use it on a regular basis. Yet again, I know why Ian chose this little optical marvel. During the very long days of a Scottish summer, when the light is good and strong, I can imagine him enjoying this super light binocular for hours on end.

    Highly recommended!

     

    The author would like to extend his thanks to Ian for lending him the Leica Trinovid BCA 8 x 20 for this review.

    Explore More:

    Ken Rockwell’s Review of the Leica Trinovid BCA 8 x 20

    Best Binocular Review of the Leica Trinovid BCA 10 x 25

    Neil English is the author of seven books in amateur and professional astronomy. He has ambitions to write a full-length book on binoculars in the future to help his fellow amateurs find genuine bargains and de-bunk myths promulgated by binocular gayponauts and con artists over the last few decades.

     

    De Fideli.

    For the Record.

    Plotina: raising the bar for grab ‘n’ go astronomy.

     

    2018 was not an unusual year here in Scotland, as astronomical observing and associated note-making are concerned.

    Total number of nights where observations were made in 2018: 137

    Percentage of nights available for observation in 2018: 37.5 per cent.

     

     

    2019: I recorded 135 nights of clear or partially clear skies. This represents 36.9 per cent of nights available for observation.

    These numbers continue to be in accord with the claims of several British historical observers; T. W. Webb, William F. Denning & Charles Grover.

    For more details on this interesting topic, see my 2018 book: Chronicling the Golden Age of Astronomy.

     

    De Fideli

    Product Review: The Celestron Trailseeker 8 x 32.

    The Celestron Trailseeker 8 x 32 mid-size binocular.

    Are you looking for a good quality mid-size binocular but don’t have £1000+ to spend on a Swarovski or a Leica or some such? Perhaps you’re looking for a nice Christmas gift for a loved one or a friend? Well, the Celestron Trailseeker 8 x 32 binocular could well be all the instrument you need!

    If you’ve been following my binocular blogs, you’ll know that I have had to follow a very steep learning curve in order to bring my readers genuinely good bargains. And while it is generally true that you get what you pay for, there are always products that surprise in very pleasant ways, and this little binocular is one such instrument!

    Celestron is not a name you’d normally associate with a high-quality roof prism binocular, but their optical engineers have successfully designed a great product in their Trailseeker range. The Trailseekers all feature full broadband multicoatings on all optical surfaces. The BAK-4 Schmidt-Pechan prisms are both phase and dielectricly coated to increase light transmission to the order of 90+ per cent, making it as efficient as ultra-premium models costing many times more.

    The binocular measures 4.8 inches wide and 4.8 inches deep, standing just 1.9″ high; so very compact and easy to store in a backpack or small carry case. The binocular can be easily mounted to a tripod or monocular for additional stability.

    My flashlight tests carried out indoors, as well as those conducted out of doors on bright street lighting and strongly backlit scenes showed that this model has excellent stray light and glare control. Indeed, its baffling of stray light is up there with the very best binoculars I have had the pleasure of testing. I was literally blown away by how resilent this binocular is to the intrusion of stray light! What that means in practice is that you get very high contrast images, rich in detail that would impress most anyone who tries them out!

    The Trailseeker has a very robust magnesium alloy chassis; a feature often only found on premium models.

    The binocular has a very strong and robust magnesium alloy chassis that is often only offered in the most expensive brands. It is also remarkably lightweight, tipping the scales at just 454g(16 oz). The strong, lightweight alloy frame also means that it will withstand knocks and bumps better than other models having cheaper plastic or ploycarbonate housings. The optics are 0-ringed sealed and purged with dry nitrogen gas to prevent internal fogging during cold-weather applications and corrosion of any metal parts used inside the instrument. The chassis is finished in a thick, rubberised green armouring that has excellent grip and which protects the main body from the elements. The underside of the binocular has neat thumb indents that make gripping the instrument very intuitive.

    The underside of the Trailseeker has neat thumb indents that make handling the instrument very easy and intuitive.

    The eyecups are of very high quality. They are made from solid metal with a soft, rubberised finish that makes them very comfortable to observe through. The eyecups twist up with two stops and hold their positions very well indeed, with absolutely no play. The eyerelief is 15.6mm which is adequate for most eyeglass wearers. Close focus is about 6 feet and the field of view is a very generous 7.8 angular degrees(136m@1000m).The dioptre setting is located under the right ocular lens and has just the right amount of friction to keep it rigidly in place from day to day, and from week to week.

    The focuser and ocular lenses of the 8 x 32 Celestron Trailseeker.

    Optically, the 8 x 32 Trailseeker packs a very powerful whallop. The instrument arrived well collimated out of the box, as evidenced by the perfectly correlated left and right eye images of a chimney located about 150 yards in the distance. The images are razor sharp with a large central sweetspot, softening as you move toward the edge, just like any other binocular. Chromatic aberration is a total non issue(I think this issue in many good quality binos available today has more heat than light). I see a lot of amateurs making bold claims about how ED glass elements make the image ‘brighter’ but in reality, the brightness of the image in the best quality binoculars has little to do with ED glass and much more to do with the quality of the coatings(particularly those of the dielectric variety) employed on the roof prism. For example, I was quite taken aback when I tested this unit out in low light conditions during dusk, when they completely outperformed a very high quality 8 x 25 pocket binocular lavished with premium ED Schott glass and dielctric coated roof prisms. There was no magic though; the very efficient light gathering capabilities of the Trailseeker’s larger 32mm objectives stole the show; it was much brighter, no ifs or buts about it!

    A Curious Aside: I wanted to get to the bottom of this somewhat ‘fishy’ claim regarding ED glass, you know; that it gives brighter images and all that, so I decided to investigate some products on line. I mean, I can see why a better focused image in an ED instrument would confer a very slight advantage over a standard achromatic unit with the same coatings, but certainly not to the extent some folk have claimed in the past. Well, I didn’t have to search long before I stumbled on a comapny, Hawke, who make a few models of 8 x 32s, and out of sheer dumb luck(not really), I was able to compare the specifications of their Endurance ED 8x 32 and their Fronier HDX 8 x 32. As you can see from the specs, the Endurance ED does indeed have ED glass, while the Fronteir HDX does not. However, it is the latter that sells for a higher retail price(£259 as opposed to £199)! The one significant difference between these models is that the Endurance ED does not have dielectric coatings on the prisms while the HDX model does. And as this chap confirms, the HDX delivers the brighter image!

    So there you have it!

    I will further investigate these claims in a later blog, God willing.

    No’ bad ken?

    NB: The author has no affiliation with any of the binoculars discussed in any of his blogs.

    A good design feature: the deeply recessed (9mm) objectives are well protected from rain, dust and peripheral glare.

    Although not my favourite size of binocular, the 8 x 32 format is great for birding and other nature studies. Its greater light grasp and generous field of view will enable the user to work under fading light more efficiently and for longer than any pocket glass. The central focuser is well made but was a little on the stiff side when I first acquired it. But with regular use, it has loosened up nicely to allow good, fast focusing on mobile targets like birds in flight, or scurrying squirrels racing up and down a tree trunk. Going from one end of the focus travel to the other involves turning the focus wheel through one and a half full revolutions.

    The Celestron Trailseeker 8 x 32 has very high quality twist up eyecups which make viewing through them very comfortable and immersive.

    The little Celestron Trailseeker 8 x 32 produces very nice images of the heavens. Looking at a rising full Moon in a frosty winter sky showed very sharp, contrasty images rich in detail, with virtually no stray light that was all too easily evident in a few lesser instruments I have tested. Moving to the edge of the field does reveal some lateral chromatic aberration and some image softening but it’s perfectly acceptable to my eye. What is more, some of these off-axis aberrations can be effectively focused out. Star fields are beautiful and sharp with a jet black sky background, and the Trailseeker has served up very impressive views of some showpiece deep sky targets such as the Pleiades, the Hyades, the Sword Handle of Orion, the Alpha Persei Association and the great spiral galaxy in Andromeda. Stars stay sharp and pinpointed across the majority of the field, with only the outer 20 per cent or so beginning to show some enlargement. That said, I found this imperfection to be very acceptable. Indeed, you would have to shell out many times the modest cost of this binocular (£126) to get anything better in this regard methinks!

    Unlike many other high quality binoculars, the accesories that come with the Trailseeker are also of exceptional quality. You get a very nicely made carry case that fits the instrument perfectly(shown above). You also receive a very nicely padded neckstrap with a Celestron orange logo.  That said, I discovered a slight hitch when I attached the supplied neck strap; when I tried to fold it around the binocular to insert it inside the carry case, it proved very difficult and caused the case to bulge outward a bit more than my liking. In the end, I elected to attach a lighter but lower quality strap to the binocular as an interim measure. The instrument also comes with a good quality binocular harness, though I’ve not tried it out for size yet. In addition, the binocular comes with fully attachable rubber ocular and objective lens covers, a microfibre lens cleaning cloth, and a neat user manual in five modern languages. The package is protected by Celestron’s limited lifetime warranty.

    The Celestron Trailseeker 8 x 32 package.

    All in all, the Celestron Trailseeker is a most impressive piece of kit and it’s obvious that the company cut no serious corners in bringing these high quality instruments to market. I think it represents exceptional value for money in a market saturated by a string of  similarly priced, but lower quality offerings. Kudos to Celestron for making these instruments available at such an incredible price(they originally retailed for over £250 when first launched but are now widely discounted)!

    Disclaimer: The instrument was purchased from Tring Astronomy Centre, the staff of which proved very professional and who insured a super fast delivery.

    Additional Information:

    Promotional Video on the Celestron Trailseeker Binocular Range.

    BBR overview of the external features of the 10 x 32 Trailseeker Binocular.

    Don’t just take my word for it: read what other purchasers have said about the Celestron Trailseekers.

    BBR Review of the 10 x 32 Celestron TrailSeeker Binocular.

    BBR Review of the Celestron Trailseeker 8 x 42 Binocular.

     

    Neil English is the author of seven books in amateur and professional astronomy, including a 665 page history of visual astronomy: Chronicling the Golden Age of Astronomy, favourably reviewed by several amateur and professional astronomers.

     

    De Fideli.

    Old vs New.

    How does a classic Zeiss binocular square up to a modern roof prism binocular?

    Unlike telescopes, which are mainly used by dedicated amateur astronomers, binoculars, for obvious reasons, are owned and used by a much broader cross section of the general population. When my students get to know me, they will inevitably have to endure my unbridled enthusiasm for optical devices of all kinds lol, and that includes binoculars. One of my mathematics students, Sandy, expressed an unusual interest in some of my instruments, and he further informed me that his parents, who run a small ferrying business at Balmaha, on the shores of nearby Loch Lomond, used several binoculars in their everyday work. My interest was further piqued when Sandy told me that his grandfather owned a big Zeiss binocular, which was inherited by his father and would eventually be passed on to him in the goodness of time. I asked Sandy whether he would be willing to bring the Zeiss binocular by so that I could have a look at it. After checking with his parents, Sandy agreed and kindly allowed me to use it for a week in order that I could assess it and give it a good clean. Naturally enough, I jumped at the opportunity!

    The instrument, a Carl Zeiss Jenoptem 10 x 50W porro prism binocular, came in a lovely leather case; a far cry form anything made in this era.

    The Zeiss Jenoptem 10x 50W complete with original leather carry case.

    The instrument had no lens caps and so had accumulated quite a bit of grime on both the ocular and objective lenses over the years. The Jenoptem, which was manufactured in East Germany(DDR), featured a Zeiss multi-coating, which helped me to date it to after 1978, when the company apparently began to apply their anti-reflection coatings to all the lenses and prisms in the optical train. So my guess is that it was probably acquired in the early 1980s. I believe Zeiss Jena offered a higher quality porro 10 x 50 in the Decarem line around the same period, but I have not had the pleasure of testing one of these units out.

    The Zeiss Jenoptem is multi-coated.

    The instrument has a very Spartan look and feel about it. Weighing in at about 1 kilogram, the Jenoptem is built like a proverbial tank, with a central focusing wheel and right eye dioptre.Turning the nicely machined metal focusing wheel first clockwise, and then anti-clockwise, all the way through its trave,l showed that it was still in excellent working condition, with zero backlash and bumping that one usually encounters with cheaper porro prism binoculars.

    As expected from Zeiss, the Jenoptem has a very well made focuser that moves with silky smoothness and with zero backlash.

    To begin the cleaning process, I unscrewed the objective housings from the front of the binocular in order to get at the inside surface of the objective lenses, which had a significant amount of grime as well as a small amount of fungal growth. Using a good quality lens brush, I carefully removed much of the dust before using a microfibre lens cleaning cloth soaked in a little Baader Optical Wonder fluid. In just a few minutes I was able to remove the remaining grime on both the outer and inner surfaces of the binocular objectives, as well as the surfaces of the prisms in the rear module of the instrument. The ocular lenses were also given a good cleaning.

    The objectives of the Zeiss Jenoptem can be accessed by uncrewing the front of the binocular from the prism and ocular housing.

    I was able to verify that the prisms were indeed coated in the same way as the objectives, although I also discovered that the steel clips holding the prisms in place had rusted significantly over time. I did not attempt to clean the clips, as I judged that doing so might throw the instrument out of collimation.

    Note the rusted steel clip holding one of the prisms in place, as well as the anti-reflection coating of the second prism(after cleaning).

    The objectives on the Jenoptem after cleaning. Note the anti-reflection coatings.

    Seen in broad daylight, I was able to verify that the lens coatings had not suffered much in the way of wearing, looking smooth and evenly applied, giving a bluish or purple cast, depending on the angle of view.

    The appearance of the objectives in broad daylight after cleaning.

     

    And the ocular lenses.

    Optical tests:

    After screwing the objective modules back into place, I was now ready to begin my optical tests of this older Zeiss binocular. I compared the views served up by this instrument with those garnered by my Barr & Stroud 10 x 50 Sierra roof prism binocular that I use almost exclusively for astronomical viewing. After setting the right eye dioptre on the Zeiss to suit my own eyes, I started with an iphone torch test to assess how the instruments fared in suppressing glare and internal reflections.

    The Zeiss 10x 50W Jenoptem(right) and my Barr & Stroud 10x 50 Sierra roof prism binocular(left).

    Because the Zeiss does not have the same close focus (~2m) performance as my Barr & Stroud, I had to place my iphone torch several metres away in my hallway in order to get the Zeiss to focus on its light. As usual, the torch was adjusted to its highest (read brightest) setting. Comparing the two in-focus images, I could see that the Zeiss fared considerably worse than the Barr & Stroud. Specifically, it picked up two fairly bright internal reflections, as well as quite a lot of contrast-robbing diffused light, which rendered the Zeiss image considerably less clean and contrasted in comparison to my control binocular. The difference was quite striking!

    After dark, I aimed the binoculars at a bright sodium street lamp and again compared the images served up in both instruments. As expected, the Zeiss showed much more in the way of internal reflections, with a lot of diffused light that produced a fog-like veil around the street lamp. The Sierra 10 x 50 in comparison served up a much more ‘punchy’ image with much better control of internal reflections and far less of the foggy, diffused light evidenced in the Zeiss.

    Next, I compared the Zeiss and the Barr & Stroud Sierra on a daylight test, examining a tree trunk in the swing park about 80 yards from my front door. Again, the difference between both instruments was striking! Although the image was very sharp in the Zeiss at the centre of the field, it was noticeably dimmer than the Sierra. That diffused light I picked up in the iphone torch test created a foggy veil that significantly reduced its contrast in comparison to the control binocular. I was also able to discern many more low contrast details in the Sierra owing to its ability to gather significantly more light than the older Zeiss. The colour cast presented by both binoculars was also noteworthy. The Zeiss threw up quite a strong yellowish colour cast  to the Sierra, which showed a much more neutral cast in comparison.

    Examining the periphery of the same field also showed that the Sierra was exhibiting a larger depth of focus than the Zeiss, which was quite unexpected, as I had been given to understand that porro prism binoculars in general show more depth of focus than their roof prism counterparts. In addition, the Zeiss showed more distortion at the edges of the field than the control binocular.

    The Zeiss Jenoptem has very tight eye relief, which I estimated to be just 10mm. The Barr & Stroud Sierra, in contrast, has much more generous eye relief in comparison- 17mm – making it significantly more suitable for eye glass wearers. Indeed, I found it difficult to image the entire field in the Zeiss, having to move my eyeball around to see the field stops.

    In summary, these daylight tests clearly showed that the venerable Zeiss was no match optically for the Barr & Stroud 10 x 50 roof prism I had tested it against. The latter was simply in a different league to the former, no question about it!

    Handling in the Field:

    The Zeiss is rather big and clunky in my small hands and is more difficult to find that optimal position while viewing for extended periods. Weighing more than 200g more than the Sierra, it is also harder to hold steady. The significantly smaller frame of the Sierra roof prism binocular is much easier to negotiate, and is simply more comfortable to use. In addition, the Zeiss has no provision to mount it on a lightweight tripod or monopod, but the Sierra, like most other modern binoculars, does.

    Astronomical tests:

    Though the weather proved quite unsettled during the week that I tested the Zeiss, I did get a few opportunities to test it out on the night sky. Once again, I used my Barr & Stroud Sierra 10x 50 roof prism as a suitable control. My first target was a bright, waxing gibbous Moon fairly low in the southern sky. The Zeiss threw up more in the way of internal reflections than the Sierra. The colour cast of the lunar surface appeared more yellow in  the Zeiss compared with the cleaner images of the Sierra. As I expected from my iphone torch tests, the sky immediately arround the Moon was also brighter in the Zeiss, with noticeably lower contrast than the Sierra. Moving the Moon to the edge of the field also showed that the Zeiss threw up more distortions than the Sierra control binocular.

    Turning to Vega high in the northwest after sunset produced good on-axis images in both binoculars, but when moved to the edge of the field, the Zeiss threw up that little bit more distortion than the Barr & Stroud Sierra. The same was true when I examined the Pleaides and the Hyades in Taurus.

    Conclusions and Implications:

    The Zeiss Jenoptem was a good binocular in its day but is clearly inferior in almost every sense to the Barr & Stroud roof binocular used in comparison. 40 years ago, the Zenoptem would have set the average factory worker a whole month’s salary to acquire new. In contrast, the Barr & Stroud Sierra can be had for between £100 and £120 in today’s market.  The value of waterproofing was made manifest in the observation of rusting of some of the metal internal components of the Zeiss. The Sierra, in contrast, is fully waterproof, o-ring sealed and purged with dry nitrogen gas to inhibit internal fogging and corrosion of any metallic components used in its construction.

    Enormous advances in optical technology over the last four decades, particularly full broadband multi-coatings applied to all lens and prism surfaces, higher quality optical glass, as well as phase coated prisms on the roof binocular, collectively allow very efficient light transmissions to the eye. This is all the more remarkable since roof prism designs usually have many more optical components than their porro prism counterparts.

    Better eregonomics in modern roof prism binoculars as well the employment of strong, low mass polycarbonate housings in their design make them lighter and easier to use than their porro prism counterparts from a generation ago. All of these add to the comfort of using them either during the day or at night when looking at the heavens.

    I had a look on ebay to see what these old Jenoptems were being offered for. I found quite a few of them selling for between £150 and £200, so not the high prices demanded by other classic binoculars.

    Like with all optical firms, time has marched on, with modern binoculars offering much better performance than earlier models.

    This comparison test must have implications for many people who already own or use older binoculars and who have not compared them to modern incarnations. And that’s as true for Zeiss as with any other manufacturer. Indeed, I was quite shocked at how much better my first quality roof prism 8 x 42 roof prism binocular fared compared to an old 7x 50 porro I was gifted back in the early 1990s. Technology has well and truly marched on! And while I like classic instruments just as much as the next guy, I see little point in using any when even modest instruments created in the modern age are likely to perform better than similar instruments made a generation ago. It’s just a hard fact of life.

    The technology of the past is certainly interesting but it would be daft to neglect the advances offered in the modern era.

     

    I would like to extend my thanks to Sandy and his parents for allowing me to test drive these old binoculars. I will be advising him to use lens caps on the optics when not in use and have also provided a sachet of silica gel dessicant to minimise moisture-induced corrosion of the optic.

     

    Neil English discusses all manner of classic telescope technology in his 650+ page historical work, Chronicling the Golden Age of Astronomy(Springer-Nature).

     

    De Fideli.

    A Magical Hour with my 130mm F/5 Newtonian.

    A grab ‘n’ go telescope on steroids.

    Anno Domini MMXIX

    My conversion to Newtonian telescopes continues apace. Though I’ve had my wonderful 130mm f/5 Newtonian travel ‘scope for a few years now, it never ceases to impress me. And my observations on the freezing night of November 18 with the same instrument only served to consolidate those sentiments.

    I set the telescope out on its trusty Vixen Porta II alt-azimuth mount about 10.30pm local time and tweaked its collimation before leaving it to cool down from an indoor temperature of 20C to an outside temperature of -5C. The optical tube is quite rigid and it holds accurate collimation very well, which is fine for general observing, but I always fine-tune the alignment of its two mirrors when going after the tightest double stars. I knew conditions would be good for such an activity by noting how little Vega was twinkling low down in the western sky, while bright stars like Capella and Mirfak located high overhead shone with a steady, planet-like gleam.

    The tube is insulated with a thin layer of cork and overlaid by black flocking material. I have noted that this affords extra thermal stability to the telescope, especially as temperatures drop rapidly(as occurs during acclimation on these cold nights). I do not use any air-blowing fans to accelerate cooling of the primary mirror, but this has never really been an issue with this small Newtonian telescope.

    After enjoying a lengthy binocular session using my 20 x 60 on a simple monopod, I began an hour of telescopic observations on a number of seasonal double stars, beginning about 11:20pm. Orion was quite well placed  east of the merdian, so I inserted my Meade 5.5mm UWA yielding 118x on a fairly low lying Rigel, carefully focused and observed the stellar image. Wow! What an amazing apparition! I was greeted by an intensely bright image of this white supergiant star, with beautiful diffraction spikes radiating outwards from a calm Airy disk. And just a little to its southwest, its faint close-in companion was easily discerned. That was enough of a confirmation that seeing conditions were indeed very good, so from there I panned the telescope northward to the better placed belt stars of Orion, examining both Mintaka and Alnitak at the same power. The images of both stellar systems were lovely and calm, with beautiful hard Airy disks betraying their companions with ease.

    From there, I moved up to a more challenging system, 32 Orionis, located just a few degrees east-southeast of Bellatrix. Coupling a 3x achromatic Barlow lens to the Meade 5.5mm yielding a power of 354x, I carefully focused the image, watching it as it raced across the field of view. Sure enough, its close-in companion(separation ~ 1.3″) proved easy pickings for this light-weight 5.1-inch telescope situated just off to the northeast of the primary. Before leaving the celestial Hunter, I had a quick look at Eta Orionis, another fine, high-resolution target, consisting of a magnitude +3.6 primary and a tight, magnitude +4.9 secondary. Both were nicely resolved at 354x, and roughly orientated east-to-west.

    Pointing the telescope at majestic Auriga, now very high in the sky, I trained the instrument at Theta, an old friend, and backed the magnification down to 236x by swopping out my 3x Barlow for a 2x Orion Shorty. That was more than enough to resolve its ghostly companion in the still midnight air.

    I spent the next quarter hour exploring some favourite doubles in Cassiopeia, notably the lovely colour contrast pair, Eta Cassiopeiae, admiring the textbook perfect images of its yellow primary and ruddy secondary at 118x. And from there I moved to Iota Cassiopeiae, beholding this beautiful triple system at 236x. These views inspired me to swing the instrument westward into Andromeda, where I quickly tracked down another binary superstar, Almach, where the telescope showed me a gorgeous, crisp image of the orange primary and widely separated blue secondary at 118x.

    After a quick look at Castor A, B and C at 118x, I trained my eyes on Propus, the ‘orange nemesis,’ as I have come to call it, which by now was reasonably well placed but still a few hours from culminating in the south. This system requires very high powers, so I broke out my 4.8mm T1 Nagler and coupled it to my 3x Barlow lens, delivering a magnification of 405 diameters. Carefully focussing the star, I watched it cross the field of view several times, observing its behaviour at this ultra-high power. During some moments, the system swelled up to become a rather unsightly seeing disk owing to a combination of thermal stress and variations in seeing, but sure enough, there was always prolonged moments where the image came together, as it were, allowing me to carefully examine the stable Airy disk. And it wasn’t long before I began to see the little blue pimple of light from its tiny secondary touching the marmalde orange primary. Having examined this system quite a few times with the 130mm Newtonian over the last few years, I have learned that good seeing doesn’t always yield commensurately good results. This I attribute to the slightly variable nature of this post-main sequence star, which can often hide the companion. But tonight, my patience paid off!

    Plotina: strutting her stuff at -5C.

    I ended the vigil shortly before half past midnight local time, by moving the telescope from my back garden to the front of the house, where I was greeted by the light of a silvery last quarter Moon, hanging above the Fintry Hills to the east. Inserting the little 4.8mm Nagler delivering 135x, I enjoyed some wonderful, crisp images of the battered lunar regolith, particularly the majestic Apennine Mountains strewn across its mid-section, near the terminator, as well as the magnificent desolation of the heavily cratered southern lunar highlands.

    Simple pleasures of a telescope.

    It was good to get out. But it was equally nice to retire the telescope indoors and reflect on the experience, sat next to a warm coal fire.

     

     

    De Fideli.