Ten Things True Christians Should Never Compromise Over.

Person Hands on Holy Bible

Finally, my brethren, be strong in the Lord and in the power of His might. Put on the whole armor of God, that you may be able to stand against the wiles of the devil.  For we do not wrestle against flesh and blood, but against principalities, against powers, against the rulers of the darkness of this age, against spiritual hosts of wickedness in the heavenly places. Therefore take up the whole armor of God, that you may be able to withstand in the evil day, and having done all, to stand.

Ephesians 6:10-13

 

  1. Defending the Doctrine of Creation: The Bible makes it very clear that all life on Earth was created by God. As we continue to probe the mysteries of life, we discover that is more complex and more wonderful than we could have ever imagined even a decade ago; an endless regress established by the Living God. An overwhelming body of evidence is now available for any reasonable person to consider, which clearly shows that Darwinian evolution is not only demonstrably false but is, in the broadest sense of the term, an evil ideology. Claiming that we evolved is blasphemy. Stay well clear of it.
  2. Defending the Rights of the Unborn: Human life begins at conception; that is what modern science has established and what the Bible consistently teaches. Killing a human life in utero, apart from exceptional medical cases, is murder.
  3. Defending the Traditional Family: Both the Old and New Testaments affirm God’s desire for humans to maintain strong, traditional family units. Sex was created by God to be enjoyed only within marriage and only between a man and a woman. God condemns all homosexual acts, declaring it “an abomination,” or in some other translations, “detestable.” The LGBT juggernaut has many characteristics in common with the Nazi movement of the early 1930s; bullying society to accept it as “good” and “normal”, when it is actually neither. They wish to destroy what God intended for humans. Christians should never succumb to pressure to normalize what God clearly considers evil or depraved.
  4. Universalism: The notion that all religions lead to God is commonly believed in our era, even by some who profess themselves to be Christian.  But that is not what the Bible teaches. Christ plainly stated that there is only one way to God and that He is “the door.” Christian doctrine divides; it is exclusive and uncompromising and was firmly intended that way.
  5. Defending the Sanctity of Human Life: The Bible teaches that all humans are made in God’s image and likeness and thus have great intrinsic value. It condemns all kinds of racism and the exploitation of one people group by another(including human trafficking and slavery). Replacement theology, the notion that the Church has replaced Israel, is not only unbiblical, it fans the flames of anti-semitism that is so prevalent in our society today.
  6. The Inerrancy of Scripture: Christians should hold the Bible as their gold standard. Its wisdom shows us how to live, what to accept and what to reject. It is not to be taken out of context and twisted to suit a particular agenda. Regular reading of the words of Scripture keeps you focused on what is important and what is not, even if wider society does not follow in the way. Just because society deems something as good, it doesn’t necessarily mean that it is right in God’s eyes.
  7. The Importance of Bible Prophecy: Many so-called ‘liberal’ Christians pay no attention to Bible prophecy. That is a grave mistake, as about 25 per cent of the Bible deals with prophecy. For example, all of the prophecies concerning Christ’s birth, ministry, triumphal entry into Jerusalem and suffering at the hands of Roman overlords were predicted with 100 per cent accuracy centuries before his birth, and Christ Himself fulfilled a whole string of other prophecies during his missionary years. Ignoring Bible prophecy is like trying to ride a bicyle without wheels. God clearly intends us to know some of the details of the future so that we can watch for the signs of His second coming. Ignoring such prophecies may well catch you off guard.

To be continued………………………………………

 

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

 

RTB Classic: 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

 

 Humanist Guddle

 

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

 

Turmeric: Wonder Root.

 

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

 

Secular Humanism as a New Religion

 

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

 

US Supreme Court Overules Calls by Militant Atheists to Demolish a World War I 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

 

Overwhelming Financial Response for Israel Folau’s Unlawful Dismissal by Rugby Australia

 

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

 

Amazonia Burning: Facts Versus Media Speculation

 

Debunking Da Vinci Code Tosh

 

Sorry: No Such Thing as “Gay” Penguins

 

Genetic Entropy

 

Dunderheid Alexa

Book Review: The Story of the Cosmos.

Putting God back at the centre of all things.

For the wrath of God is revealed from heaven against all ungodliness and unrighteousness of men who suppress the truth in unrighteousness, because that which is known about God is evident within them; for God made it evident to them.  For since the creation of the world His invisible attributes, His eternal power and divine nature, have been clearly seen, being understood through what has been made, so that they are without excuse. For even though they knew God, they did not honor Him as God or give thanks, but they became futile in their speculations, and their foolish heart was darkened.  Professing to be wise, they became fools..

                                                                                                                 Romans 1: 18-22

 

With Carl Sagan’s naive vision of the Cosmos now in tatters, it’s time to put our Creator back in the driving seat.

Tune in soon to read the full review….

 

De Fideli.

 

N=2: Why I’m the Very Proud User of a Barr & Stroud Savannah 8 x 42 Binocular.

An alpha binocular in many ways, except for the price.

Semptember 9, 2019

I’ve said it before, and I’ll say it again: there is something in a name.

In my ongoing investigation into binoculars, I’ve discovered that, like telescopes, you don’t always get what you pay for. In particular, if a product offers advanced optical features like a full multi-coating on all air to glass surfaces, ED elements, or phase corrected roof prisms, it doesn’t necessarily translate into a solidly functioning optic. I’ve tested products purported to have premium optics but upon inspection, did not deliver all the goodness that they were promising in cleverly devised youtube promos and fancy specification sheets etc.

One company that has bucked this trend is Barr & Stroud, a once prestigious optical and engineering firm, established in Glasgow, Scotland, that at one time supplied all manner of optical instruments to the British navy during two world wars. Like many other large optical firms established in Britain, it underwent considerable re-structuring over the decades. Today, the brand name is owned by Optical Vision Limited(OVL) and began producing binoculars for the civilian market in 2011, moving production to China.

My enthusiasm for the brand began just a year ago(2018), when I initiated testing a variety of their binoculars in different price ranges. Like many others who have looked through their instruments, I was duly impressed by the incredible bang for buck of their offerings, with optics that punched well above their modest price tags.

Of particular note is the Barr & Stroud Savannah 8 x 42, which delivered wonderful, wide-field, high-contrast and colour pure images of the Creation. Unlike other brands in the same price range, which offered so-so performance, especially off-axis, these binoculars maintained excellent control of the same aberrations. The massive 8.2 degree field of these 8x glasses is sharp across the vast majority of the field, with only the extreme edges showing significant distortion.

My first Savannah was actually purchased on the second-hand market, and that out of sheer curiosity. Expecting such a wide angle binocular to show average optical quality as one moves off axis(like so many others I’ve tested), I was very pleasantly surprised to discover that this excellent image quality was being maintained to the extreme edge of the field. Indeed, the view, in retrospect, was almost too good to be true. Unfortunately, the dioptre ring, which is situated in a very unusual place on this binocular (just ahead of the large focus wheel) developed a fault, which necessitated its return to OVL for repair. What I actually received was a brand-new instrument and so I was able to asess the performance of two samples of the Barr & Stroud Savannah that inspired the writing of this blog.

Two great performers: the Barr & Stroud 8 x 42 Savannah(left) and the 10 x 50 Sierra(right).

Built like a proverbial tank, the fully weatherproof and nitrogen purged Savannah 8 x 42 is heavier than many competing models on the market. Indeed, at 819 grams, it even weighs more than my 10 x 50 Barr & Stroud Sierra binocular (which also delivers excellent optics and mechanics for the buck). Outwardly, the Savannah has a rather Spartan look and feel about it, with features that are simple and rather understated. The eye cups are of very high quality, which can be set to three positions, and with a very generous 18mm eye relief, is ideal for eye glass wearers and those who like to observe without glasses. When twisted up, they click into place with a reassuringly loud “thwack” sound, and which remain in that position even after excess pressure is applied. Indeed, I rate these eyecups very highly and amongst the best that I have sampled thus far in my binocular education.

The high quality multi-coatings on the 42mm objective lenses of the Savannah. The reader will also note how deeply recessed the objectives are. This helps suppress glare in bright, daylight conditions.

The focus wheel is large and moves smoothly without any stiction, either clockwise or anti-clockwise, making it easy to change the position of best focus from as close as 2 metres to beyond infinity. The tension is just right; not too stiff and not too slack.

All the accessories that come with the Savannah are of high quality; including a hard black clamshell case, a padded neck strap with the B&S logo and rubber objective and eyepiece lens caps that can be affixed to the binocular and so are not easily lost in routine field use. The instrument also comes with the company’s 10-year warranty.

The large and responsive focus wheel on the barr & Stroud Savannah 8 x 42.

The new binocular turned out to be every bit as good optically than the first one I returned! Indeed, it could even be that little bit better! Images are bright and razor sharp, rich in contrast and colour pure. Though it contains no ED elements, the instrument shows only a trace of chromatic aberration, and only if you go looking hard for it. Like I said before, I don’t consider the presence of ED glass as a feature that is necessary on binoculars of this specification. Crank up the power nearer to the resolving magnification, and it’s a different story. But in this realm, what I’m more interested in, and which is far more important in the scheme of things, is how well the binocular is put together.

Roofs are complex instruments, requiring engineering skill and very careful assembly of the components. Some firms know how to do it well, others don’t…..methinks.

The high quality twist up eyecups on the Savannah click securely into place with a loud “thwack” sound. Note the tough, texturised rubber amouring covering the instrument.

My assessment of binocular optics involves the usual procedures employed by other reviewers, but I have also devised much more demanding tests to learn how well the light is being transmitted though the optical train.  What I have discovered is that many purportedly high-end roof prism binoculars (based solely on their recommended retail price) often show considerable flaring and annoying internal reflections when observing strongly backlit daylight scenes. In addition, night time testing on bright artificial street lights and the full Moon also provide solid clues as to what is going on inside the test binocular(which unfortunately, are all hermetically sealed!!).

One particularly stringent test is to direct an intensely bright beam of light from my iphone into the binocular to see how it deals with glare and internal reflections. No roof prism binocular, no matter how well made, can completely pass these tests;

All fall short:- but what astonished me was how well they were suppressed in the Savannah 8 x 42. Unlike many other models, which reveal too much glare and bright ghosting across the field, both my 10 x 50 and 8 x 42 Barr & Stroud instruments came out with truly excellent results! In particular, the degree of glare suppression and control of internal reflections present in the Savannah was fully the equal of a world class binocular: – in this case, the Swarovski 10 x 42 EL Range:. Where you will often pick up diffraction spikes and flaring from bright street lighting in an inferior instrument, as well as contrast-robbing diffused light around such artificial light sources (not to mention internal reflections), my new Savannah 8 x 42 shows up very little. This is easily seen in regular daylight testing, where the images thrown up by the instrument show very high contrast, allowing very fine details to be easily discerned.

Performing a small, bright light test in the comfort of my living room. Note the small amount of daylight left in the room to asist imaging objects immediately behind and around the light source(my iphone torch).

I thought long and hard about why such an economical instrument offered such unreasonably excellent control of stray light, and then I remembered how the same company made high-quality optical instruments for the British navy. Out at sea, where sunlight is strongly reflected off the water, glare suppression would have been a high priority for any optic used for long distance surveillance. Although it remains an interesting conjecture on my part, it could be that the technicians who assemble such binoculars have specialised knowledge on how to keep those internal light leaks at bay. Afterall, once upon a time, not doing so might well have made all the difference between life and death!

Some important details coming through on the focussing wheel. The ocular lenses are hard coated for extra durability.

Whatever the reasons for such optical excellence, the wonderful colour correction, contrast and suppression of stray light make the 8 x 42 Savannah binocular an excellent choice for birders and naturalists. I cannot think of a better instrument – without dropping an additional few grand – to take along with me to observe the deluge of autumnal colours that are only just emerging, as the trees shut down for a long, winter nap. But, as I’ve discovered, the 8 x 42 also delivers knock-out views of the celestial realm!

As I recall, it was with some trepidation that I decided to try the Savannah. I was leary of the advertised field of view -143m@1000m or 8.2 angular degrees. I had learned of other binoculars delivering such enormous fields of view but having disappointing off-axis performance. Better to have a binocular that delivers a smaller field of view with tightly focused stars near the edge than suffer the indignation of seeing those stars swell up in the outer part of the field. It’s just not tennis!

But my fears were completely allayed once I tried them out on the night sky.  I was literally blown away! Not only was the field of view enormous, but it was very well corrected, right to the edge of the field. Believe me, I have experienced some real howlers, where stars are pinpoint sharp in the centre of the field but when moved off axis, the same test stars balloon into enormous blobs when positioned near the field stop. Starfields remain crisp throughout the field of the Savannah binocular making it an excellent choice for casual star gazing.

Although the binocular can be mounted on a monopod for increased stability, I have rarely used it in this capcaity. Instead, I enjoy hand-holding the instrument where the 8x magnification makes it considerably easier to hold steady over a 10x instrument. That said, if I wish to push the instrument to see the very faintest stars, a monopod is a good way to go. Some binocular authorities I have read suggest that you can gain up to 1 stellar magnitude deeper if the image is stabilised.

The very well corrected, ultra-wide field of the Barr & Stroud Savannah  8 x 42  provides stunning views of large clusters of stars. For example, it provides knock-out views of Melotte 20, otherwise known as the Alpha Persei Association, where the field is littered with several dozen hot, white stars varying in glory from the third to the 10th magnitude. But perhaps my fondest night time experience with this wonder binocular was seeing the entire Sword-Handle and Belt stars of Orion in the same field on a cold, dark December evening.  And where my 10 x 50 Sierra binocular can just frame the Hyades, the Savannah frames the same picturesque asterism with plenty of room to spare!

The large, sensibly flat field of the Savannah has proven excellent for watching meteor showers. I just aim it at the radiant and watch to see if some shooting stars flash across the field. I also love exploring the interface between land and sky. Indeed, as described in this blog, the Savannah is my instrument of choice to explore Moon and starscapes rising above trees and buildings near my home. The Savannah has re-kinded my interest in observing the full Moon when the clouds pass over it. I adore the play of light and colour the binocular serves up in its enormous field of view.

The 8 x 42 is always by my side while using my backyard telescopes. It has greatly increased the speed and efficiency of finding faint fuzzies. Once I locate the target with the binocular, the telescope is pointed at the same spot of sky where I can rapidly hone in on the object.

A binocular that doesn’t want to go inside its hard case.

Readers will forgive my rather vaunted praise of this amazing instrument. But I feel it is justified. In an age of con artists and let downs, this instrument is nothing short of a ray of sunshine. It offers exceptional value for money and has sated my desire to acquire anything else in this mid-sized binocular class. I can hand-on-heart recommend it to other observers looking for an excellent all-round binocular for day and night time use. You’ll not be disappointed!

Thank you for reading!

 

Neil English is the author of several books in amateur and professional astronomy.

 

 

De Fideli.

In Search of a Good Pocket Binocular.

Far from the madding crowd.

August 30 2019

Pocket binoculars are a popular choice for many birders, hikers, ramblers and all-round nature lovers who want to get up-close and personal with God’s illustrious creation. If you have scenery like this right on your door step, trust me, you’ll be keen to take along some binoculars to enhance and extend what your eyes can see;

A pocket binocular usually has objective lenses less than 30mm in diameter and offer magnifications anywhere from 7x to 10x. They are small and in general fit inside a pocket, giving rise to their name. Like all other binoculars, pocket glasses come in a range of prices, starting from just a few tens of pounds right up to £1000, depending on the make and model. The cheapest models are to be generally avoided, as they often have very shoddy optics and/or mechanics, but things get very interesting once you move into the mid-priced market, where you can acquire decent optics and mechanics for prices anywhere from £70 up to a few hundred pounds. But is buying a pocket binocular from a reputable optics firm a sure way to get decent quality? I’m going to have to concede that the answer is “no.”

That’s based on my experiences mainly with two models from the well established companies: Bresser(Germany) and Kowa(Japan). Both models were acquired from amazon and possess similar optical specifications, the Bresser Pirsch 8 x 26mm and the Kowa SV 8 x 25mm DCF, which set me back £97.00 and £83.00, respectively. Both models are roof prism designs, have fully multi-coated optics and phase corrected prisms to maximise the amount of light that is transmitted to the eye, and to render colour-true images in bright daylight conditions.

The Bresser Pirsch 8 x 26mm was exciting to unpack, as it looked the bizz from the online images and the specifications promising “premium quality worthy of their prestigious lifetime warranty.” And when I opened up the case to have a look at the binocular, I must admit to being instantly impressed; here was a stylish looking instrument with a beautifully made, ‘Swarovski like’ open bridge design. The focuser was large and constructed from high quality metal. In operation, it was a joy to use, moving with silky smoothness, with no stiction when turned clockwise and anti-clockwise through its travel.

The Bresser Prisch 8 x 26 compact binocular.

All the accessories were of high quality, which included a padded next strap, an oversized nylon case, instruction manual, rubber objective and eyepiece covers, and a lens cleaning cloth.

The twist up eyecups are amongst the best I have encountered, clicking through a number of stages from fully retracted to fully extended.They hold their positions very well, even when significant pressure is applied to them. The dioptre setting is situated in a sensible place; just under the right barrel. It is stiff and once set in place it will not easily budge.

The beautifully designed twist up eyecups are amongst the best I have personally encountered with four positions. Here they are shown fully extended.

Handling this binocular was particularly pleasurable, as the open bridge design allows for firm gripping either with or without gloves, and can easily be focused using one or two hands. The binocular is lighter than it looks: ~ 290 grams

Firm grip: handling the Bresser Pirsch 8 x 26 binocular.

The Baader Pirsch 8 x 26 has outstanding mechanical quality.

The instrument comes with quality accessories, including a padded cary case and quality neck strap.

But mechanics are only half the story of any binocular. How did the optics fare?

Collimation was tested by mounting the binocular securely on a monopod that was firmly sandwiched in place between two planks of wood on my garden fence, and examining the fields of view presented by both barrels of the instrument. This showed that the binocular was indeed well collimated, certainly within factory tolerances. I had no trouble instantly merging the images once the optimum IPD was selected. Close focus was estimated at about 6.5 feet, in line with the stated specifications. So far so good.

The quoted eye relief for the Pirsch binocular is 15.6mm. That should have been plenty good for eye glass wearers. However, I found that only by pressing my glasses hard against my eyes could I observe the full field. It was not comfortable and so I think folk that have to use eye glasses when using this binocular will struggle.

Testing collimation of the Pirsch binocular. And yes, this wee instrument does have a tripod connecting thread!

True to the specifications, the binocular offers a fairly wide field of view. I measured it as about 6.6 degrees(in agreement with its stated FOV of 117m@1000m). Compared with an entry level test binocular with no phase coating(but with fully multicoated optics), the image was better corrected for seidel aberrations across the field of view, revealing noticeably less field curvature, pin cushion distortion and lateral colour than the entry level unit. On axis, no chromatic aberration could be seen at the edges of a nearby telephone pole as seen against a bright, overcast sky, while the control did show a little bit. And while the image looked good in many daylight scenes, it wasn’t long before I discovered that the binocular was not showing the contrast I had been enjoying with my wife’s Opticron Aspheric LE 8 x 25mm pocket binoculars. Looking into brightly backlit scenes revealed a potential problem with the Pirsch; there was some flaring and internal reflections coming through. So that caused me to investigate the matter further.

A cursory examination of the binocular review literature revealed something rather shocking to me. Very few reviewers had the presence of mind to investigate and report back on light leakage within the binocular, which can lead to very incomplete knowledge on how an instrument ought to behave under real-life situations. I consider it essential information for any savvy buyer, as it doesn’t matter how well a binocular is appointed with high-tech features if they can’t manage to adequately suppress stray light in the optical train. To me, this is Optics 101.

Fortunately, this is easily done by carrying out an indoor test using an iphone with its torch turned up to its maximum brightness and examining the in-focus images of how that light is delivered to the eye whilst looking though the binocular in a darkened room a few metres in the distance. You can also glean good information on how well a binocular will deliver by pointing the instrument at a bright street light or the full Moon(this is a considerably less severe test but an important one in any binocular assessment).

Well, the tests were very convicting. Not only was there many bright internal reflections but the Pirsch binocular seemed to be causing bright light sources to become diffused across the field of view, manifesting as a contrast-robbing, circular haze. And it was the same when I pointed the binocular at a bright sodium street light.  I had not seen such terrible control of stray light since the day I tested a very inexpensive Celestron Nature DX 8×25 unit several months back. Needless to say, I was not a happy bunny! Incidentally, even my entry-level control optic showed far less flaring and internal reflections than this purportedly “premium” instrument!

As another control for these tests, I employed my most excellent Barr & Stroud Savannah 8 x 42, which shows remarkably little flare and diffusion of light under the same conditions. Indeed, as I already communicated in a previous blog, this superb instrument possesses the same level of glare and internal reflection control as a Swarovski EL Range 10 x 42 unit I recently subjected to the same tests. The reader will note however, that no roof prism binocular, no matter how well built it is, can completely eliminate such optical side effects.

My control binocular for flare and internal reflection testing; the Barr & Stroud 8 x 42 wide angle, which delivers superbly contrasted images even in harsh lighting conditions.

A curious aside: I wonder will flare and internal reflection testing suddenly enjoy an upsurge on future binocular forums? Hmmm.

I suspect that many of these pocket binoculars are not tested for flaring and/or internal reflections because these small instruments are not recommended for night time use and so any problems they have in this regard might easily slip below the radar. I would check out your instrument to see how it fares in this regard.

For me, a binocular, no matter how small it is, should pass these tests. Remember, we’re not looking for perfection here. If you’re viewing a city scape at night or gazing at the Moon from time to time, your pocket binocular should have minimum light leak and scatter, so that it does not show up in ordinary use. Is that really too much to ask for?

I don’t think so!

Verdict: The Bresser Pirsch 8 x 26 possesses excellent mechanical features but its optics do not match its mechanics. Not recommended. Luckily I had registered the instrument with Bresser to enable the terms of the guarantee to be fulfilled.

So how did the Kowa SV 8 x 25 fare in comparison?

Here is what the company promised.

Well, the package I received came in a small box, containing the binoculars, instruction manual, carry strap and eyepiece caps but no objective covering caps. Unlike the Pirsch, the Kowa is double hinged, which enables you to fold the barrels under the bridge,. making it truly pocketable. You can get an idea of the transportable size difference of both the Pirsch and the Kowa by comparing the size of their carry cases;

The carrying cases for the Pirsch(right) and Kowa binocular(left).

My first impressions of the Kowa SV 8x 25mm binocular were favourable. It is small and rather cute looking. Kowa engineers deliberately designed the instrument to be very lightweight using modern materials. It has a very well armoured body with a tough, coarse- feeling rubberised exterior.

The Kowa SV 8x 25 is a well made binocular using modern materials to reduce the weight. Like the Pirsch, the dioptre setting ring is under the right barrel.

The eyecups twist up and down like the Pirsch  but appeared to have only two fixed settings; fully extended or retracted.  You can however, set the eycups at any position and they will hold their place.

The Kowa glass had what seemed to be immaculately applied anti-reflection coatings on the eye lenses and objectives, which almost disappear when examined head on. Kowa also apply a hydrophobic coating on the elements that allegedly repels water, oil etc, making cleaning the exterior optics that little bit easier.

The kowa ocular lenses have nice anti-reflection coatings. Note the smaller eye lenses on the instrument.

And here is what the objectives look like under inspection. Kowa engineers applied extra armouring around the nicely recessed objectives for added protection.

The objective lenses on the Kowa are nicely recessed and have immaculately applied anti-reflection coatings.

The focuser is made of a soft material that effortlessly moves clockwise and anti-clockwise. I found that it was smooth and very responsive in use, with little in the way of stiction.

A close-up of the Kowa focuser.

Like the Pirsch, the instrument is fully waterproof and is nitrogen purged. The optics are fully multi-coated and a phase coating applied to the Schmidt-Pechan roof prisms. But at this stage in the game, I had learned not to place my hope in an instrument based solely on these claims. I recalled the story of the little Celestron Nature DX which also advertised such advanced optical treatments, but failed miserably in field use.

Like the Pirsch, the Kowa barrels were well collimated and the field of view was found to be slightly smaller than the Pirsch, at just over 6 degrees. But when I began to assess the optics of the unit, I hit my first snag. The smaller eye lenses on the instrument made it very difficult for me to accurately position my eyes and I immediately noticed that I was frequently experiencing black outs as I moved from one daylight target to another. It did have better eye relief than the Pirsch though, allowing those who wear eyeglasses to use it fairly easily.

Worse still, I noticed that when I was observing with the Kowa in bright daylight conditions outdoors, I could see a faint ghosting in the field which would only vanish when I pressed my eyes tightly against the eyecups. The contrast was noticeably better in the Kowa images though, with excellent control of colour and seidel aberrations. But I was worried about the ghosting I saw, and so decided to perform my iphone torch test to see what was what.

Such testing revealed some problems. While the horrible diffused light I saw in the Pirsch was far better controlled(but nonetheless present), the test revealed a pretty bad case of on-axis flaring. My heart sunk as I contemplated the implications of the test. This would also show up in nightime test I told myself, and I waited until the evening to find out for sure.

Turning the unit on a bright sodium lamp all too easily revealed a pretty bad dose of on-axis flaring which ruined the image. And though internal reflections were much better controlled in the Kowa than in the Pirsch, the flaring on bright nocturnal lights was, quite frankly, very annoying and downright unnaceptable. And yet again, my entry-level control binocular fared better than the prestigious Kowa in the same tests.

I really hoped Kowa, a company which enjoys a strong reputation for precision, high-end  sport optics, would be able to deliver a binocular image without this degree of flaring, but  alas, it was not to be.

Visibly upset, I contacted Kowa UK to report the result. They quickly responded and apologised to me for the fault, explaining that this was a very ” unusual” finding.

Well maybe. But it didn’t stop me immediately packing up the instrument and its accessories and returning it to amazon. I received a full refund, but had no interest in  testing out a replacement unit. Once bitten twice shy.

Note added in proof: Control of light leakages bares little correlation to the price paid for these binoculars. For instance, my Barr & Stroud 8 x 42 and 10 x 50 roofs have a retail value of about £130 and £80, respectively, but have excellent control of stray light. If these did so well, why couldn’t the little pocket binoculars deliver?

Ich verstehe nicht.

Another pretender:

Same old same old: the Olympus 10 x 25 has the same optical design as the Kowa SV pocket binocular.

What about the Olympus 10 x 25 WPII?  I took a chance on this product also. Retailing for about £70, it offered all the same features as the Kowa binocular. Indeed it was almost a carbon copy of the Kowa, except for the magnification and focus wheel, but alas it also showed too much daylight glare when pointed at brightly backlit objects, so that went straight back to amazon as well. Though sharp in the middle of its relatively massive field(6.5 angular degrees), the Olympus binocular showed very distorted images in the outer 30 per cent of the same portal. So, not great, either.

An Old Reliable: It’s not all doom and gloom though. Compared with the three binoculars I had evaluated thus far in this blog, my wife’s Opticron LE Aspheric 8 x 25 pocket binocular is in a completely different league optically. With minimum flare, no blackouts and good control of internal reflections, the little classically styled Opticron is very well built and just works, time after time after time.

A classically styled pocket binocular that just works; the Opticron LE Aspheric 8 x 25.

Now a few years old, the Opticron LE Aspheric features multi-coated optics and silver- coated phase corrected prisms. Aspherical ocular lenses produce a very flat field that renders undistorted images right to the edge of the field. And though its field of view is a little restricted at 5.2 angular degrees, it’s a nice tidy portal with very well defined field stops.

The Opticron Aspheric LE has simple twist up eyecups for those who do not use eyeglasses while observing.

The eyecups have just two positions; up or down. With 21mm eye relief, the instrument is extremely comfortable to view through. The double-hinge design does allow the barrels to fold up to pocket size though;

Snug as a bug in a rug.

It has its own built in lanyard so there is no need to fiddle about attaching a neckstrap. The original Opticron Aspheric LE (with the green logo) is a bit on the urbane side though; it is not weatherproof and the outer armouring is smooth and non-texturised. But a few years back, Opticron gave this pocket binocular a bit of a makeover; the new Aspheric LE is waterproof and purged with dry nitrogen, making it that little bit more versatile than the first generation model. Eye relief is reduced to 16mm, which should still be plenty good for all users. It also has new eyecups and a  re-designed focuser. Details can be found here.

Nice big(17mm) eye lenses on the Opticron Aspheric LE make for highly immersive views.

The instrument is more expensive than the Pirsch and Kowa models though; ~£120. But that extra cost does buy you peace of mind, or so I’m led to believe.

I”m going to order up the new model to determine how consistent the quality is. I will report back in a wee while to tell you how I get on with it.

Watch this space!

September 10 2019: Well the new Opticron pocket binocular arrived safely today. So, what was in the goodie box?

The Opticron Aspheric LE WP 8 x 25 pocket binocular and its accessories.

The binocular was purchased from Tring Astronomy Centre, and I elected to have it shipped to me via expedited 24 hour delivery. The cost, including postage, came in at £120. Like everything else I have received from Tring in the past, the product arrived in perfect nick. It was double boxed, witth the package including the pocket binocular, an instruction manual, lens cleaning cloth, and warranty card, and a stylish padded carry case with the Opticron logo on the front. I even received a £75  wine voucher!

The New Opticron Aspheric LE is now water and fog proof.

Unlike the original model, the make and specifications on the new model are embossed on the upper bridge. The armouring is also slightly more texturised than the sleeky, first generation model.

The original model had plastic eyecups, but the newer incarnation has what appears to be a slightly more comfortable rubberised overcoat.

Using the Optricon Aspheric LE WP is child’s play; just twist up the eyecups and they click into place. There are no intermediate settings. If you waer glasses, leave the eyecups down.

I rather like the simplicity of the eyecups on this instrument. There are only two positions: fully extended or fully retracted. The 16mm eye relief is plenty good enough for eyeglass wearers(verified by my own tests).

The focus wheel is larger and a little easier to work with than the original model.That will make it easier to use with gloves on. I did find it to be a wee bit on the stiff side though, but I figure with more use, it will became easier to negotiate.

The newer Opticron Aspheric LE( right) has a slightly larger focusing wheel.

The ocular lenses are the same on both models; good and large and easy to engage with.

Both models have the same optics, including large ocular lens.

The neoprene carry case is very nicely made and fits the pocket binocular perfectly:

A very nicely fitting padded neoprene carry case will keep your optics safe while not in use.

Close up of the Opticron labelled padded case.

You can probably guess by now what I did first: yep, I performed my torch test to see how well stray light was being controlled inside the barrels. Well, it passed with flying colours; not perfect, but perfectly acceptable! Indeed, it was very similar to the results I obtained for the original model. Later, I performed a test on some sodium street lights and the results were very good. Only very slight ghosting and no annoying glare.

What a relief!

Conducting some observations during the day also delivered very pleasing results.The images are very bright, sharp and colour-pure, thanks to good quality glass, anti-reflection coatings and a silver mirror coating on the prisms. Like the original model, backlit scenes show excellent control of glare and certainly enough to satisfy the vast majority of users. The aspheric ocular lenses did a great job maintaining a very flat field nearly all the way to the field stop. Close focus was astonishing! I measured it at just 51 inches (~1.3m), so significantly less than the advertised 2 metres. A nice bonus!

Clearly the quality control on these instruments appears to be very good indeed.

Weighing in at just 291 grams, and with its double hinge design, folding it up and storing it in your pocket is a breeze. It’s nice to have a pocket binocular that does exactly what it says on the tin.

Alas, I was unable to perform my last test on the bright Moon owing to the presence of a weather system (the remnants of hurricane Dorian) passing over Scotland, but the results on stray ligt control gives me no cause to be concerned. It will pass the full Moon test with flying colours!

A quality pocket binocular in the palm of your hand!

A Curious Aside: Here’s a binocular review posted on September 11 2019.

Wow!

The reviewer even conducted tests for glare and flaring etc!

Shockeroonie!

Don’t take my word for it; look at some other reviews of the Opticron Aspheric LE pocket binoculars to better establish a consensus:

Calvin Jones, Irish author, birder and naturalist

Diane and Michael Porter’s Birding Binoculars

Feathersoptics review

 

Conclusions and Lessons Learned:

It is clear that good optical performance cannot be gleaned from checking the specifications of a pocket binocular. Claims of a product offering fully multicoated optics and phase corrected prisms etc count for nothing if they cannot suppress glare and internal reflections to an acceptable degree. In this blog I have sampled but a few models that fell short of my expectations. In the end, only the Opticron Aspheric LE 8 x 25 delivered the readies.

The best way to proceed with acquiring a pocket binocular is to test it out in person, if at all possible, before handing over your hard-earned cash. The reader should also be leary of any binocular review that does not mention or test for glare, flare and internal reflection. This is an essential feature that must be controlled if you are to derive the best performance out of your pocket optics.

Life’s too short to look through bad glass!

Opticron also manufacture a series of more expensive pocket binoculars in their BGAT PC Oasis series. These will also be a good bet, but you’ll have to cough up another £100 to acquire one. I may test one of these models out in the future.

I did consider a few ED models in my quest. For example, the Hawke Endurance ED 8x 25 has a wider field of view and retails for 20 per cent less than the Opticron(which has no ED glass), but is it as well built? And how do the optics fare? To be honest, I don’t know, as there wasn’t any discriminating reviews available for me to make a decision, but they might be worth a punt. I did contact Hawke asking them how well they suppress glare in their small pocket binocular and received a very quick reply. Here is a copy of my correspondence with the company:

……………………………………………………………………………………………………………………..

Dear Sir/Madam
I am writing to inquire about glare suppression and internal reflections in your Hawke Endurance 8x and 10x 25mm pocket binoculars.
I have been testing a few brands and some show very annoying flare and/or ghosting when pointed at a bright street lamp or a bright Moon.
Will your products pass such tests?
I appreciate that no binocular can completely eliminate these but all I am asking for is no obvious ghosting when pointed at the moon or strongly backlit scenes in daylight.
Thanks in advance of your reply.
Sincerely
Neil English.

from: Hawke UK uk@hawkeoptics.com

Hello Neil,

Thanks for your email and interest in Hawke Optics. The internal components of our binoculars are treated to be as glare resistant as possible. We use a combination of matte finishes and ribbed surfaces to prevent a flat reflective surface. However, it will never be possible to completely eliminate reflections like you are talking about and so even with these countermeasures, our binoculars will show some white out when looking towards a bright light source.

Kind regards,

Alex Jenkinson

……………………………………………………………………………………………………………………………….

I wonder if any of you have tested the Hawke model? If so, I’d be very keen to hear from you. Failing that, I might just go ahead and purchase one to do a full review; warts and all.

I would also trust the optics in the Pentax AD bocket binocular, which also retails for about £100. But that’s not based on direct experience with this model, only an inference made from using two other binoculars from their line.

For a few hundred pounds more you can acquire excellent pocket binoculars from the ultra-premium end of the market from Zeiss, Leica and Swarovski. However, I don’t think you’ll notice any big optical differences between the Opticron and these though. The value lies more in their mechanics than anything else.

For me, I feel the Opticron delivers everything I could wish for in a pocket binocular; both mechanically and optically. It’s a quality product that will stand the test of time if looked after properly.

Well, I hope you found this blog to be informative.

Good luck with your quest to find a good pocket binocular!

 

Neil English’s newest title, The ShortTube 80: A User’s Guide, hits the bookshelves in early November 2019.

Post Scriptum: Shortly after local midnight on September 12 2019, I ventured outside to see if I could gain a glimpse of the bright and nearly full Moon, that had just past the meridian and about 17 degrees above the southerly horizon. I compared the Bresser Pirsch 8 x 26 to the Opticron Aspheric LE WP 8x 25. A brisk westerly breeze was blowing, quickly shifting the clouds over and then away from the Moon. During one such clear spell I pointed both instruments at its silvery white face and studied the images.

Result: The Pirsch showed annoying glare and some obvious internal reflections in the field. The glare also brightened the backround sky around the Moon, reducing contrast. However, the Opticron unit showed no visible internal reflections and only slight flaring when the Moon was placed just outside the field. The backround sky around the Moon was much darker to boot, showing clearly superior image quality to the “premium” Pirsch.

 

De Fideli.

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

Portable power. The author’s 130mm f/5 travel Newtonian telescope.

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

     

    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.

     

    Caveat Emptor!

    As you may gather, I’ve taken a keen, active interest in testing out binoculars with an aim to providing my readers with good quality products that won’t break the bank. As part of that process, I needed a few entry-level models to compare and contrast them with other products purporting to provide better optical quality. In one transaction, I purchased an Eyeskey labelled 8 x 32 roof prism binocular on August 5 2019 from eBay. It was brand new and set me back £37.79, taking about two weeks to ship directly from China to my home in Scotland.

    Here is a photo of what I received:

    The Eyeskey Package.

    Here is a close-up photo of the Eyeskey binocular; the reader will note the texturing of the armoring and distinctive tripod adaptor cover

    The Eyeskey 8 x 32 roof prism binocular.

    Here is what it looks like from the ocular end:

    Note the plain 8 x 32 & Bak4 Prism labelling on the focus wheel.

    And here is a photo of the tethered rubber objective lens covers as well as the thumb indentations on the underside of the binocular:

    Note the tethered rubber objective covers and thumb indentations on the Eyeskey.

    After inspecting the Eyeskey binocular and its accessories, I recalled another binocular, marketed by a company called Avalonoptics.co.uk, which I had come across in a previous internet search.

    Here is Avalon’s 8 x 32 Mini HD binoculars( all images taken from their website):

    Avalon 8×32 Mini HD Binoculars BLACK

    Here is an image of the entire package:

    Here is an image of the writing on the focusing wheel:

    Note the thumb indentations on the under side of the barrels on the Avalon:

    And here is an image of the tethered objective covers on the Avalon:

     

    Next, I took a look at the specifications of both models.

    You can view the Avalon specs here

    And here are the Eyskey specs( source eBay):

    8561-8X32_01

    Both claim to be fully multicoated, are nitogen filled and fog proof, but there is no mention of a phase coating on either model.

    There is a few differences in the quoted specifications. The advertised field of view is 6.78 degrees for the Eyeskey and 6.9 degrees for the Avalon model; quite close. Eye relief is quoted as 18mm for the Eyeskey and 15mm for the Avalon, but these figures can often be incorrect or at least misleading(as I will explain in another up-and-coming binocular review). The Eyeskey has an advertised weight of 18.3 oz = 519 grams, whereas the Avalon has a quoted weight of 416 grams.

    Weight can also be misleading though, as it can vary according to whether you include the lens covers and strap etc.

    The boxes look pretty similar with just different logos on them, same goes for the neck strap and generic instruction sheet.

    Now for the price comparison:

    Eyeskey 8 x 32: £37.79

    Avalon 8 x 32 Mini HD: £119(recently discounted 20% from £149)

    Finally, have a look at this youtube presentation of the said Avalon Mini HD binocular here.

    Is the Eyskey 8 x 32 model worth the £37.79?

    I suppose for what you get it’s a bargain.

    But what about the Avalon?

    I’ll leave that up to you to decide!

    Caveat Emptor!

     

    Neil English debunks many telescopic myths in his new historical work, Chronicling the Golden Age of Astronomy.

     

    De Fideli.

     

    The Field of Glory.

    Companion under the stars: the Pentax PCF 20 x 60 binocular.

    Preamble

    Visual astronomy can be enjoyed in a variety of ways. We can use the eyes our Creator designed for us to marvel at the beauty of the night sky. Or we can employ a telescope to get those up-close views, where both resolving and light gathering power are needed to make sense of what we see. But there is also the binocular perspective, which fills a niche set midway between that of the eye and that of the telescope.

    On the night of August 25 2019, I found myself doing all three. After an hour of admiring dim and hard to find deep sky objects using my largest telescope; a 12″ f/5 Newtonian reflector, I sat back in my observing chair to drink up the naked eye heavens above me. The air was still, with no wind, and only the occasional screech of a barn owl breaking the silence. After a few months of twilit skies with only the brightest stellar luminaries on display, true darkness had now returned to the landscape. By 11:30pm local time, the bright constellations of Cygnus, Lyra, Hercules and Aquila had passed into the western hemisphere, with Bootes now sinking perilously close to the western horizon. And over in the northeast, Cassiopeia, Perseus and Auriga were making excellent progress climbing ever higher in the sky.  Andromeda and Pegasus were also ripe for exploration. The familiar asterism of the Plough hung low over the northern horizon, far below the North Star, Polaris, around which the great dome of the sky wheels. With no Moon in the sky, and good transparency, the river of light from the northern Milky Way stood out boldly, snaking its way across the heavens from east to west. It was the perfect opportunity to break out my big binocular, a Pentax DCF 20 x 60 and boy did it deliver the readies!

    Using a monopod for big binocular astronomy on the go.

    As I described at great length in the preamble linked to at the beginning of this blog, the Pentax DCF 20 x 60 combines excellent optics with great mechanical features in a relatively light weight package; ideal for use with a monopod. The instrument attaches in seconds to a strong, high-quality ball and socket mount head and can be transported easily from one place to another. Delivering a pristine, flat field some 2.2 degrees wide, the Pentax had already delivered gorgeous views of the heavens during Winter and Spring evenings, but I had not yet had an opportunity to sample the skies of late Summer/early Autumn with this powerful optical instrument.

    My first target was M13, easily found about one third of the way from Eta Herculis to Zeta Herculis in the western edge of the famous Keystone asterism. I had already admired this big and bright globular cluster earlier in the 12″ telescope at high power. The 20 x 60 binocular revealed a bright fuzzy bauble about half the size of the full Moon and neatly sandwiched between two 7th magnitude field stars. Of course, the binocular could not compete with the majesty of such a cluster as presented in a large, light bucket, but it was nonetheless a lovely sight with wonderful contrast against a jet black sky.

    I then moved over to Lyra and centered the bright summer luminary, Vega, shining with its intense blue-white hue across the sea of interstellar space, and surrounding it a swarm of fainter suns, including the famous Epsilon Lyrae of double star fame. Moving into Cygnus, I turned the binocular on Beta Cygni, known more commonly as Albireo. With a steady hand, I could easily resolve the beautiful, wide colour contrast double star; marmalade orange and blue-green secondary. Panning about eight degrees due south of Albireo the binocular field soon captured that remarkable little asterism that is the Coathanger (Collinder 339). What makes this a particualrly engaging visual sight is the uniformity of the stars comprising it; most shining with a soft white hue and of the sixth magnitude of glory.

    Moving about five degrees to the east of the Coathanger, and forming a neat little right-angled triangle with the stars of Saggita, the celestial Arrow, I chanced upon the large and bright planetary nebula, known commonly as the Dumbbell (Messier 27). Unlike other planetary nebula, M27 is one of the few that present clearly in the relatively low power view of the binocular. Try as I might though, I could not see the hourglass shape of the nebula as seen in telescopes at higher power; it was more or less circular in form, softly glowing against the background sky at magntude 7.4.

    I didn’t have to travel far for my next visual treat; M71, a faint globular cluster situated nearly exactly midway between Gamma and Zeta Saggitae. With its population of mostly 12th magnitude suns, M71 presented as a misty patch in a glittering hinterland of August star light.

    Adjusting the ball & socket head of the monopod, I ventured back into Cgynus and centred the lovely binocular double,  commonly referred to as 0^1 Cygni. Like a wider version of Albireo, the 20 x 60 binocular presented their fetching colours perfectly, orange and turquoise (magnitude 3.8 and 4.8, resepctively). I could not however clearly resolve the fainter 7th magnitude component parked up against the orange member, which a small telescope so easily shows.

    Eager to examine another stellar hinterland, I moved the binocular so that Deneb was centred in the field of view. Well, this binocular portal took my breath away! Hundreds of suns of varying degrees of glory smattered haphazardly across the field, and here and there the excellent contrast of the instrument also showed up some small nebulous patches set adrift among the starry hosts. With its very generous 21mm of eye relief, the big binocular was delivering very comfortable and immersive views. It was almost as if I could reach out my hand and touch the heavens!

    With midnight approaching, I noticed that the great square of Pegasus was clearing the rooftop of my house, and a little further to the east, Andromeda, the Chained Lady, had by now gained a decent altitude. Eagerly, I trained the binocular on a foggy patch clearly seen with the naked eye. I had arrived at the Great Andromeda Galaxy (M31). The lenticular shaped core was big and bright and beautifully contrasted against a sable sky, and with averted vision it was not hard to trace the spiral arms all the way to the edges of the field. Its fainter companions, M32 and M110, were also seen with a concentrated gaze, the former being easier to see and just a half an angular degree to the south of M31. M110 proved much more elusive though, being larger and fainter than M32 but nonetheless fairly easy to pick off about a degree away to the northwest of the main galaxy.

    Moving into Cassiopeia, the binocular presented field after field of brilliant starlight with a wonderful variety of colours. Many faint open clusters came to life as I inched the binocular through its mid-section; NGC 457(otherwise known as the E.T. Cluster) was very engaging, especially the bright, 5th magnitude white super-giant star marking its southern border, and then on into the heart of M103, a compact little open cluster just to the northeast of blue-white Delta Cassiopeiae. My notes from a good few years back informed me that the cluster presented as unresolved in an inexpensive 15 x 70 binocular, but this instrument, with its significantly higher magnification, was just beginning to hint at some individual stars within the cluster. A comely quartet of stars flanking the southeastern corner of the Messier cluster made the scene especially engaging to study. Panning very slowly eastward through the constellation, roughly from Delta to Epsilon Cassiopeiae, my eyes picked up many faint open clusters, including NGC 44, 663, 559 and 637.

    By about a quarter past midnight, Perseus had risen to a good height above the northeastern horizon, and I eagerly sought out the famous Double Cluster(Caldwell 14), easily located as a foggy patch to the naked eye roughly mid-way between Perseus and Cassiopeia. With great excitement, I moved in on my target, all the while bringing to mind the stunning views I had reported with this binocular last Winter. Wow! I wasn’t disaapointed. The entire field exploded with stars of various hues; white, blue-white, creamy yellow and sanguine, the two sumptuous open clusters beautifully resolved with curious fans of stars radiating outwards from their centres. Sharpness was extreme from edge to edge, with the stars presenting as tiny pinpoints. I believe that this 20 x 60 binocular renders these awesome natural spectacles as good as you’ll ever see them; the combination of decent light gathering power and magnification using both eyes is a match made in heaven! This was a pre-season teaser though. The Double Cluster will only increase in majesty, as it continues to climb higher in our skies over the next few months.

    Moving to Algol, the Demon Star, I then navigated about 5 degrees west from it, where I was pleasantly surprised by how easily I was able to pick up another lovely open cluster, M34. The powerful double eye on the sky resolved a few dozen members, mostly 7th, 8th and 9th magnitude members sprawled across an area of sky roughly the size of the full Moon. Many fainter members, largely unsresolved by the instrument, gave the cluster a very lively, translucent appearance, a consequence I suppose of the inability of the binocular to cleanly resolve its faintest members, which go all the way down to magnitude 13. Sometimes, not seeing things clearly adds to the visual appeal of deep sky objects.

    From there, I moved back to Alpha Persei and placed it at the upper edge of the field of view of the 20 x 60. Even though the binocular has a fairly restricted 2.2 degree true field, it was able to pick up a generous assortment of bright O-B stars at the heart of the moving cluster Melotte 20. It was a beautiful sight!

    With the time fast approaching 12:30 am, I picked up the 20 x 60 astride its monopod and moved to the front of the house, where my gaze met with the Pleiades rising above the Fintry Hills to the east of my home. Though it was still at a fairly low altitude, the 20 x 60 produced a draw-jopping view of this celebrated open cluster, its orientation being rather lobsided compared with how it appears later in the autumn. Many of its fainter members were extinguished by virtue of its low altitude, but it was still a magnificent sight. Again I would concede that large binoculars produce the best views of the Pleiads. And it will get better, night by night, as Autumn turns to Winter.

    With a waning crescent Moon not far away from rising, I retired from the field of glory with a head full of vivid memories. This was just the beginning though. God willing, it will show me even grander sights as the days continue to shorten through the autumnal equinox and onwards toward the December Solstice.

     

    Neil English’s new book, The ShortTube 80, A User’s Guide, will soon be published by Springer-Nature.

     

     

    De Fideli.

    Exploring the Skies Over Rural Pembrokeshire.

    Slova Beach, Pembrokeshire, Wales.

    De omnibus dubitandum

     

    Preamble

    Results from Northwest, Central and Southwest Scotland

    Results from Central Scotland

    Results from Northwest England

    Results from the Republic of Ireland

    5″ f/12 refractor versus 130mm F/5 Newtonian Shootout

    Investigating the Jet Stream

    Llanrhian-Berea

    Wales is a country of outstanding natural beauty, with deep valleys, high mountains and rolling hills. Its rugged coastline boasts many pristine(blue flag) beaches and pretty little towns that are a joy to visit and explore. Like Scotland, frequent weather systems move in from the Irish Sea, purging the air of particulates that create excellent transparency for remote daytime viewing and astronomical adventures when the Sun sinks beneath the horizon.

    Newgale, Pembrokeshire.

    We decided on Wales because my brother and his young family had moved there last year from northeast Scotland, where he settled in a large country house dating from the mid-19th century, situated on the outskirts of the small village of Letterston, some ten miles north of Haverfordwest and 6 miles inland from Fishguard, where you can catch a ferry across the open sea to Ireland. And besides, we’d never vacationed in Wales before, so we had no good excuse but to make that 400 mile journey south from our home in rural, central Scotland.

    St. David’s Cathedral, a place of worship since the 6th century AD. From the City of St. David’s, Pembrokeshire, southwest Wales.

    The house is situated on five acres of choice land, secluded on all sides by woody glades, and even sports a large fish pond fed by a couple of fresh streams meandering through the estate. The homestead is surrounded by beautifully tended lawns and flower gardens that thrive because of frequent rain showers which keep them lush and well watered. It is a very peaceful place, with little in the way of light pollution, save for the glow from Haverfordwest, which illumines the southern horizon. Higher up though, the night sky is truly glorious, where the summer Milky Way winds its way from Perseus in the northeast to Sagittarius in the south.

    Lower Summerhill.

    We arrived late on Monday July 29, after spending much of the day travelling. I was glad that night was rainy and overcast, as I was exhausted from the journey and in no mood to pull out a telescope. Besides, we were all eager to catch up with my brother and sister-in-law, and my boys stayed up well beyond their bed times nattering to their first cousins. The next night was overcast but remained dry.

    But the next three evenings were clear.

    The sojourner: Plotina, the author’s nifty 130mm f/5 Newtonian reflector. The pond lies in the background.

    I brought along my portable 130mm f/5 reflecting telescope, which had proven to be spectacularly successful in ‘scouting out’ good sights to view the heavens from. It had already travelled a few thousand miles all around Britan and Ireland, where I had tested the skies on a number of choice double stars to establish something of the seeing conditions across the British Isles, some of which are highlighted in the links provided above.

    As I have communicated many times in the past, this little Newtonian had greatly exceeded my expectations. Sporting a high-quality 5.1″ primary mirror and an upgraded secondary, when cooled and collimated, had shown me arguably some of the best views I have ever experienced with any grab ‘n’ ‘scope. With its state-of-the-art reflective coatings and modest( 26.9 per cent) central obstruction, it has consistently delivered the readies in all weather conditions, from warm, muggy summer nights to freezing winter evenings. It has proven itself to be a first rate double star ‘scope, which, under the right conditions, renders beautiful, colour-pure images of the Creation. Three eyepieces attended the instrument in its foam-lined aluminium case; a 25mm Celestron X-Cel LX, delivering a power of 26x in a well corrected 2.3 degree true field. This is my favourite wide-field scanning ocular used with the 130mm, great for observing star clusters and large deep sky objects. For medium power work, I brought along my Parks Gold 7.5mm, a delightfully simple eyepiece with wonderful contrast. Coupled to a 3x Barlow it delivers a power of 260x, which is a good working magnification to use on a variety of closer doubles. For higher power work, I also took along my Meade 5.5mm Ultra Wide Angle(UWA), delivering a power of 118x in a true field of ~ 0.7 angular degrees, useful for close up observations of smaller deep sky objects. And when coupled to the 3x Barlow yields a power of 354x, great for ferreting out the most difficult pairs. Still, it must be mentioned that this instrument can handle 100x per inch of aperture, if push comes to shove.

    Beach Gear

    The only other instrument I took along with me was my Pentax 9 x 28mm DCF LV roof prism binocular. I figured I would get a lot of use out of this, as we planned to visit many places where they would come in handy. I had intended to bring by trusty 8 x 42 but these had to be sent away for repair/replacement. And although the small Pentax binocular was the perfect accompaniment by day, I regretted not bringing my 10 x 50 roofs. Indeed, I really ought to have brought along both instruments with me.

    Conditions at the site:

    Dusk, looking westward.

    Being located so close to the coast, the evenings are often breezy from onshore winds, but by dusk, they usually abate, creating very tranquil conditions. What I also noticed was how quickly and heavy the dew is at this site; significantly more aggressive than at home. Indeed, my observing sessions were limited by dew, as the telescope has no fans or dew heaters to keep it at bay. And I had forgotten to take along my flexi dew shield, so unfortunately, it was always a race against time.

    I encountered no midge flies while making observations; a God send! They’d eat you alive in Scotland!! What you can get here is horse flies though. Thankfully they left me alone throughout the vigils.

    Session 1: July 31 2019

    The first object to emerge from the dusk was mighty Jupiter, appearing ever more bright as the twilight gave way to proper darkness and a few degrees higher in the sky than it appears up in Scotland.. Beginning around 20:55UT, I charged the telescope with the 5.5mm Meade UWA yielding 118x, and turning it on the giant planet, I was greeted with a very nice image. All four Galilean satellites were visible, a couple to the east of the planet and a couple to its west. The planet itself was revealing some very fine details, several tan-coloured bands and bright zones. The north equatorial belt was very prominent but its southern counterpart showing visible disjointing. 118x was producing a nice image scale, plenty high enough to see fine detail but not so enlarged as to wash out the same details. It was nice to greet an old friend like this. Its lower altitude back home had often blurred these finer details so much that I had all but abandoned the planet during this current apparition, holding out for better conditions when the planet gains altitude in a few years from now.

    Studying the giant planet for a few minutes also suggested to me that the seeing was going to be good for double star testing, and lo, it most certainly was!

    21:03 UT: Epsilon Lyrae 1& 2; beautifully resolved into four components at 260x

    21:06 UT: Epsilon Bootis; text book perfect rendition of this gorgeous colour-contrast double. Beautifully rendered at 260x

    21:10UT: Delta Cygni; textbook perfect split of this system with its bright primary and faint secondary. Easy picking at 260x

    21:15 UT: Finder scope had already dewed up, so I detached it from the ‘scope, capped up the main telescope and brought the finder indoors to let the condensation evaporate.

    21:57 UT: Resumed observations of double stars, starting with Pi Aquilae, which was very easily split at 354x

    21:29UT Lambda Cygni: a sub-arc second pair. Airy disks touching at 354x but not cleanly disjointed.

    21:31UT: Mu Cygni, easy split at 260x

    21:50UT I turned back to Jupiter and immediately noticed the Great Red Spot (GRS) near the eastern limb. Even finer planetary details were coming through now in the darkened sky. I decided to cap up the optics on the main ‘scope once again to ward off dew, removed the finder scope and brought it indoors. This would be a good opportunity to make a measurement of the current Central Meridian (CM) II longitude of the GRS.

    I re-emerged from indoors at 22:20 UT, uncovered the 130mm’s optics and re-mounted the finderscope. Aiming once again at Jove, the GRS had moved considerably further west but was not yet at the central meridian. Over the next twenty minutes I watched carefully using the Meade 5.5mm UWA(118x) throughout and was finally satisfied that the GRS was on the CM II meridian at 22:41UT.

    I had to wait until I returned home to turn this timing into a CM II longitude for the GRS. Downloading the latest edition of WinJupos freeware, I entered the longitude, latitude and time I estimated the spot was crossing the meridian( 22:41 UT). The software computed a value of 312.4 degrees:

    WinJupos computation of the GRS transit across central meridian.

    I then searched to find a reliable source that quoted the most up-to-date CM II longitude determination of the GRS and found this recent(as of June 5 2019) posting on the Sky & Telescope website. See here for interest. The source quoted a value of 308 degrees!

    That’s very close to the measurement I made!

    Cool or what?

    No’ bad,………ken.

    Yessiree, the 130mm is a fine planetary telescope, allowing me to make some pretty challenging measurements more or less routinely.

     

    Vigil ended at 22:50UT owing to build up of dew on the telescope’s secondary mirror.

     

    A Curious Aside: Oculus Historiae

     

    Session 2: August 1 2019

    The second night was, to all intents and purposes, a carbon copy of the night before; a windy early evening which gave way to tranquil conditions as sunset approached. Starting at dusk around 21:00 UT, I set the telescope up on its Vixen Porta II mount and lowered the tripod legs a little to enable the kids to get a decent look at the two bright planets that were quite prominently on display low in the south: Jupiter and, several degrees further east, majestic Saturn. Keeping the magnification at 118x, the telescope displayed crisp views of both worlds, but alas, no sign of the GRS. My boys had seen these worlds before, of course, but not their cousins.The twins(Luca & Amabelle) were gobsmacked with the sight of Saturn, in particular, through the telescope. It was the first time they had ever seen this world ‘live.’ They chuckled among themselves saying, ” it’s just like you see in a book!”

    Spying Jupiter and Saturn through the 130mm Newtonian. From left to right: Luca, Amabelle, Oscar and Douglas.

    Well maybe, but the instrument was able to cleary show the Cassini Division as well as some subtle banding on this giant world 880 million miles away! I judged the image to be very good considering its woefully low altitude.Like Jupiter, it promises to yield better views for us far-northern observers in the years ahead.

    A little later, my sister-in-law, Rhiannon, came to have a look at the planets and some showpiece deep sky objects. She was amazed to discover that the instrument didn’t cost very much, even with all the modifications done to it.

    Beginning at 21:15 UT,  I began my double star tests, in rapid succession, and using the same magnifications I had used the previous evening. And the results were exactly the same: very good seeing conditions, enabling high resolution double star work to be conducted.

    I then took myself off to visit the Ring Nebula(M57) in Lyra, three bright globular clusters, M3 in Canes Venatici,  as well as M13 and M92 in Hercules. The good light grasp and resolving power provided very engaging views in these dark skies, which I had, by now, deemed very similar in quality to another site in Wigtown, southwest Scotland (and also near the coast!) The Whirlpool Galaxy(M51) looked great at 118x, as did M81 and M82, which were still fairly high up in the north.

    I ended the telescopic vigil with quick looks at some easy multiple star gems including Mizar & Alcor, Gamma Delphini, Iota Cassiopeiae (with its 3 beautiful stellar members), Albireo and the lovely O^1 Cygni system.

    The telescope had dewed up by 21:50UT, at which time it was packed up for another night.

    At 22:45 UT, as every one else had retired for the night, I ventured out again with my 9 x 28 binocular, enjoying the river of starlight through the Milky Way. But what most excited me was the siight of Perseus, now set much higher in the northeastern sky. Aiming at Alpha Persei, I brought the binocular to my eyes to behold that beautiful, sprawling wonder that is Melotte 20. It’s a spectacular binocular sight, even wth this small instrument. I couldn’t help pining for something larger though, like my 8 x 42, or better still, my 10 x 50. But I suppose, we live and learn!

    I retreated from the field of glory around local midnight, for we had much to do the following day.

    Low tide at Solva.

    Session 3: August 2 2019

    Like the last two days, August 2 was warm and sunny, though today some high altitude cloud produced much more in the way of hazy conditions than on the previous days. And that haze remained into the evening and over night. As a result, transparency was much reduced to my chagrin, since I wanted to do a little bit more deep sky observing. But as any regular observer worth his or her salt will inform you, hazy conditions often portend a good, stable atmosphere. Even before commencing telescopic observations it was easy to see the conditions were excellent, with the stars twinkling even less than they had done on the previous nights.

    At 21:20 UT I began with a quick look at Jupiter, now near its maximum altitude for this location, with the 130mm charged with a power of 118x. Some really fine details were showing up as the planet drifted across the field of view, proving once again that such an instrument is a good choice for observing the bright planets, especially in grab ‘n’ go mode.

    At 21:30 UT, I commenced my double star observations, using the same magnifications as described on July 31, and, one by one, they all succumbed to the formidable resolving power of this telescope. Conditions this evening at this site were as good as I have seen elsewhere(Ant I); there was zero turbulence, the stars resolving to beautiful, hard Airy disks in every case. I also recorded a good split of the components of Lambda Cygni this evening, separated by 0.94″  at a power of 354x, though I would have liked to have had some additional magnifying power on this tough target( I have used 405x with this system in this telescope on many occasions).

    This vigil was ended at 22:05 UT.

    Conclusions: On three consecutive nights, the 130mm reflector served up excellent, high-power views of a selection of double stars, adding to my list of good places to observe from. Once again, the little Newtonian delivered the goods!

    Do I attribute this to good fortune?

    Sheer dumb luck?

    Absolutely not!

    It is the observer that creates opportunities. Diligence and determination are all that is required. The British Isles offers many places to do such work and is a far cry from the bad reputation our lands have garnered on more than a few internet forums.

    Britain and Ireland are open for business and I would take any comments claiming the contrary with a large dose of scepticism.

    Think tooth fairy, Yeti, Darwinian evolution…..you get my drift.

    One thing is certain though; you’ll never know unless you get off your backside and do some real testing!

    Memories from our trip back up north:

    There were a few other nights where the skies were partially clear, allowing to me to make some short binocular tours. Indeed, the pattern was much the same as I have noted at a few other places in the UK and Ireland.

    The picturesque esplanade at Aberystwyth.

    We said our goodbyes to our hosts on Monday morning, August 5, when we set off northward. Our first port of call was Aberystwyth, a beautiful university town set on the coast. We enjoyed a delicious lunch, followed by a walk along its magnificent esplanade  and were sorely tempted to have a dip in the sea, but time was against us, as we had to make our way across the border into England, where we would spend a night in Liverpool.

    The beach at Aberystwyth.

    I’m not a fan of cities in general, but I had never visited Liverpool in all my years of living in the UK. The real reason for the visit was to do a tour of Anfield, the home ground of the 2019 Champion’s League winners, Liverpool F.C. My eldest son, Oscar, was in his element, being a die-hard Liverpool fan.

    After booking into our hotel and having a bite to eat, we set off on a walk down to Liverpool docks in the late evening, taking in the amazing buildings that decorate the site,

    One the amazing municipal buildings at Liverpool docklands.

    Liverpool is also the ancestral home of the Beatles, and sure enough, it wasn’t long before we came across a reminder of the city’s most famous sons;

    Larger than life bronze casts of the Beatles.

    The city lies next to the Mersey estuary. On the evening we arrived, the tide was fully out at sunset, which made for a very pretty sight;

    Sunset on the Mersey Estuary.

    Taking an open-top bus around Liverpool, we learned a lot of historical information from the tour guide (speaking in broad Scouse) before being dropped off at Anfield. Countless bus loads of folk were making the pilgrimage to the home turf of one of England’s most successful football teams. I suppose for the faithful, it was like a visit to Mecca.

    Anfield Stadium( August 6 2019).

    The all-important silver ware.

    Though we enjoyed many warm and sunny days in Wales, extending into our short trip to Liverpool, as we hit the mountains of northern England, sunshine gave way to torrential rain;

    By bye to sunny skies.

    Indeed, much of the rest of August brought very unsettled weather to Scotland, but at least the farmers were happy. Rumour has it that this was a record summer for growing grass and making hay! Unfortunately though, it also meant that our lawns, which were trimmed before we left, had to be cut down to size again upon our return.

    Oh Bliss!

    It was good to get away and spend some quality time with family. No doubt, I’ll be back again to sample its excellent skies with my little Newtonian reflector.

     

    Neil English travels through four centuries of time to bring you many more inconvenient truths concerning the Newtonian reflector in his tome, Chronicling the Golden Age of Astronomy.

     

    De Fideli.

    Test Driving the Swarovski EL Range 10 x 42 Binocular.

    The Swarovski EL Range 8x 42 binocular.

    For more than a generation Swarovski Optic has been supplying premium quality sports and nature optics to an international customer base. Beginning back in 1935 when Wilhelm Swarovski started manufacturing small 6 x 30 binoculars, his business expanded greatly during World War II and by 1949, Swarovski launched itself as a separate company, manufacturing very high quality binoculars, spotting ‘scopes and rifle sights at their large facility at Absam, Austria. Employing more than 800 employees, Swarovski has a turnover of in excess of 100 million Euro with 90 per cent of its revenue generated from exports.

    Swarovski produce a very extensive range of premium quality binoculars for birders, hunters and nature enthusiasts, ranging from small pocket-sized instruments(8 x 25) right up to large 56mm aperture instruments for specialised, low light work.  Having recently re-kindled my interest in using binoculars, I have had the privilege of enjoying two Swarovskis, an older EL 8.5 x 42mm (owned by my coalman, Graham) and a first generation EL Range 10 x 42mm, owned by a neighbour of mine (Ian), both of whom are keen hunters. In this blog, I wish to discuss the latter instrument in some detail.

    Introduced in 2011, the EL Range 10 x 42mm features top-notch optics and state-of-the art laser-based range-finding technology that enables the user to accurately estimate distance to any given distance between about 33 and 1500 yards with an error of just +/- 1 yard. In addition, its built-in inclinometer allows angular measurements up to 90 degrees, thereby covering every angle compensation you are likely to use (especially when hunting in mountainous regions). Powered by a CR2 lithium ion battery, up to 1000 measurements can be made before replacing it. The second generation of the EL Range series was introduced in 2015, which offers some improvements over the original, including faster estimation of distance.

    Ian very kindly allowed me to borrow his first-generation EL Range 10 x 42 for a short spell. For my tests, I concentrated solely on the optical and mechanical performance of the instrument, which were conducted over the space of 24 hours between July 22 and 23 2019, which included indoor, bright daylight, dusk and night-time observations. For those of you who wish to learn more about its ranging capabilities, check out this link.

    The Swarovski EL Range 10 x 42: optical and mechanical excellence.

    Mechanical design: The EL Range 10 x 42 weighs in at about 32 ounces. This was surprising given the presence of two prominent arches placed on the underside of the instrument. These apparently increase the stability of the instrument when making hand-held distance estimates.

    The underside of the EL Range 10 x 42 has raised arches to help stabilise the instrument while conducting distance measurements

    The 10 x 42 Range has individually tunable eyepieces with the dioptre compensation is accessed by pushing up the ring at the base of each ocular. The twist up eyecups are a work of art, plain and simple. Beautifully made, they click up and down effortlessly and hold their positions even when considerable downward force is applied. They can also be unscrewed if they need to be replaced or to access the ocular lenses for cleaning.

    The exceptionally well designed all-metal twist up eyecups are a joy to adjust with soft rubber  eye contacts to make viewing as comfortable as possible.

    The focus wheel is also a joy to use. With very finely machined threads, focusing from nearby to far away objects is effortlessly achieved via its buttery smooth motions.

    The beautifully designed large central focus wheel is buttery smooth with no stiction.

    Like all other mid-sized binoculars by Swarovski, the instrument has an open bridge design which is very stable and easy to balance and the well-designed hinge allows for quick and easy adjustment for my optimum inter-pupillary distance. The optics are housed in magnesium barrels to reduce overall weight and are overlaid by a tough, protective rubber overcoat that is very easy to grip. The optics are hermetically sealed and nitrogen purged to prevent any internal fogging. The instrument is water resistant to depths of up to 13 feet.

    Overall, I would rate the mechanics on this binocular to be of exceptionally high quality.

    Optics: Just like its mechanical excellence, Swarovski spare no expense incorporating the very finest optics inside their binoculars, and by that I mean the highest quality optical glass(which includes extra-low dispersion components) and state-of-the-art anti-reflection coating technology. The prisms are of Bak-4 Schmidt-Pechan design, which require phase coating to optimise light transmission. Swarovski like to think of the entire optical system acting as one collective unit which they call “Swarovision.” The light transmission is 91%( a figure derived from their technical data).

    The objective and ocular lenses immediately exposed to the air are also treated with a proprietary coating that repels water, oil and grease. They also will not fog up on cold days if one accidentally breathes on them.

    The state-of-the-art anti-reflection coatings of Swarovski objectives. Note also the deeply recessed objectives which cuts down peripheral glare during field use.

    After I had made adjustments to the dioptre settings for my own eyes, I excitedly began tests on the 10 x 42 during bright evening sunshine. Examining a range of targets including the top-most boughs of some nearby conifers, rooftops and the broad tree trunk of an old Horse Chestnut tree, I was most impressed at the crystal clear clarity of the images. Comparing these to my own Barr & Stroud Savannah 8 x 42 binocular, which gives a ‘warm’ tone, the Swarovski was more neutral toned in comparison and ever so slightly sharper to my eyes. But what most impressed me was that the image was also a little brighter than my 8 x 42! This became more apparent as the sun began to set and dusky twilight ensued.  If the Swarovski was transmitting 91 per cent of the light collected to the eye, the Savannah was probably transmitting something more like 85 per cent.

    Comparing binocular views can be very enlightening. Top: the Barr & Stroud 8 x 42, bottom: the Swarovski EL Range 10 x 42 .

    The field of view of the Swarovski is 6.4 degrees, the images being perfectly flat across the entire field thanks to specially designed field flatteners in the ocular lens assembly. This makes the field stop stand out that little bit more than in my 8 x 42 wide-angle Savannah (sporting an 8.2 degree true field). Examining the edge of a telephone pole some 30 yards in the distance revealed a sliver of chromatic aberration in the Savannah but I could discern none at all in the Swarovski.

    Edge of field correction was also superior in the Swarovski. Where the Savannah clearly revealed some pin-cushion distortion at the extreme edge of the field, the Swarovski revealed little or none in comparison.

    Going indoors for a while, waiting for the sky to get maximally dark, I conducted my iphone torch test to see how both instruments would compare in regards to their ability to suppress internal reflections. This is a severe test on any optic. I darken the room and turned my iphone torch on at maximum brightness. Then, viewing from a comfortable distance, I aimed both instruments at the light to see what was what. A while back, I had tested the Barr & Stroud Savannah 8 x 42 (and the 10 x 50 Sierra made by the same firm) and noted how well they suppressed glare and internal reflections. To my delight, I found both the Swarovsji and the Savannah to reveal broadly similar results; both units very aggressively blocked annoying internal reflections! Note that this test is far more severe than pointing the instruments at a bright Moon. Indeed, some instruments(including some top of the range models) that passed the Moon test faired considerably worse in this more discriminating test.

    Star testing and an encounter with a waning Gibbous Moon:

    At this time during the summer, the twilight which dominates during late May, June and the first half of July begins to give way to significantly darker skies. So around local midnight, I ventured out again to test the binoculars on some starfields poking through some cloud banks that were beginning to break up as the night progressed. lying on my recliner, I aimed the binoculars on some star fields in Lyra and Cygnus. The view through both the Swarovski and the Savannah was excellent, with the former offering a flatter field from edge to edge. Contrast was excellent in the Swarovski as well, and the stars presented as tiny, sharp pinpoints. It also reached that little bit deeper than the Savannah as one would expect in comparing an 8x optic to a 10x optic of the same aperture. The Savannah, although possessing a wider field of view, also showed some distortion of the stellar images at the edge of the field.

    At around 00:45 UT, a bright waning gibbous Moon was rising in the eastern sky and had gained enough altitude to see it from my back garden. Both instruments presented very pleasing views, but with the subtle differences in colour tone and image scale. The Savannah produced a warmer tone with a very slight yellowish tinge in comparison to the Swarovski, which was correspondingly cooler and a more neutral white appearance. The low altitude brought out the usual atmospheric refraction in both instruments. In the Savannah, a very slim sliver of blue was observed around the edges of the Moon, while in the Swarovski the same sliver was more yellow than blue. The greater magnification of the Swarovski was immediately apparent however, where it presented significantly more in the way of crater details than the lower power Savannah.

    Before packing up, I enjoyed watching the fast moving clouds passing near and over the lunar image in both instruments, creating a wonderful dispaly of natural colour. It was good to get out and do some observing in a reasonably dark sky once again.

    Now, I suppose you are wondering whether I would recommend the Swarovski to a prospective buyer, especially since I do not, in general, have a tendency to use or promote premium equipment. I’m going to say ” yes” with this one, for reasons I would like to outline here.

    It boils down to how much you intend to use the instrument. For astronomical telescopes, most folk get to set up and use their gear maybe once or twice a week(if you’re especially keen)  for a few hours at the most, though I suspect that this is probably the exception rather than the rule. If you are a keen glasser however, you will likely use binoculars far more frequently and for long periods of time. The Swarovski is a beautifully made, precision instrument that will endure knocks, extremes of weather and much more besides. It comes with a very nice quality case and  carrying strap and the company stands behind many innovative accessories that will only add to your pleasurable experiences.  It will often be your only companion in the great outdoors. Without a doubt, a premium binocular like this will hardlly ever fail, so you are investing in a durable, high- quality instrument that will grow as your interests grow and diversify.

    I can say all of this with absolute confidence. Why? Because within a couple of days of testing both instruments disaster struck with my Savannah.

    If you recall, I bought the Savannah second hand from an ebay seller. It worked flawlessly even with continued use every day, for many months. I was intending to bring it along with me to southwest Wales for a family vacation, when the dioptre ring developed a fault. Although it still worked quite well, I found I had to turn it to the extreme end of its travel before getting a well focused binocular image! The failure upset me, but thank goodness, the story had a silver lining.

    An Act of Generosity

    I contacted Optical Vision Limited(OVL), the company that now owns Barr & Stroud, as well as other small players in the mid-priced binocular market. I explained the problem to them, at which point they asked if I could provide proof of purchase. I then explained to them that I actually bought it used and that I just assumed that the 10-year warranty was transferable to new owners. Unfortunately, OVL informed me that the warranty was not transferable. However, they were aware of my long-standing work for the astronomical community and kindly offered to honour the warranty. Well, the relief on my face was all too clear to everyone and I accepted their gracious offer. I dispatched the instrument by courier to their depot in Bury St. Edmunds, Suffolk, just prior to setting out on our 400 mile journey to Pembrokeshire.

    While we were in Wales, OVL contacted me to say that they would be sending me a new binocular to replace the old one and asked if I would choose a day for the courier to deliver the instrument. I arranged to have it delivered the day after our return home.

    Sure enough, the new Savannah 8 x 42 arrived in perfect nick. Excitedly, I opened the box to find the brand-new instrument carefully packed inside. I had my new Savannah and it worked perfectly!

    After a year of considerable grief in my professional career, something good finally happened!

     

    Contentment.

    Thank you so very much OVL!

    What the experience taught me

    I once purchased a pair of perfectly serviceable 10 x 50 binoculars for $30 at an electronics retailer. These binoculars showed that if you choose carefully, you can get good optics for relatively little money. So what do you get if you spend ten times as much? In terms of the actual view, not as much as you might expect. Yes, more expensive binoculars have better optics that will deliver more light to your eyes and sharper images, but the difference is not night and day. What the extra money does buy you is mechanical quality. Expensive binocuars can withstand the inevitable bumps  and knocks of everyday use without trouble, and having focusing mechanisms that are sure and precise.

    Gary Seronik, Editor of Sky News and former Sky & Telescope columnist and author of over 200 articles under Binocular Highlights.

    This quote from Seronik’s book, Binocular Highlights (2nd edition) is very true. In my case the Savannah binocular (mid-priced in the scheme of things) gives you about 90 per cent of the optical performance of the Swarovski. Yes, the latter is definitely the better instrument, but it is the mechanical design and not the optics where it especially excels. That said, I have become very fond of the Savannah, as it feels right in my hands, and punches well above its weight. I don’t know how the fault with the dioptre ring developed but what I can say is that I will be keeping a very close eye on it. And if any issues arise with it again, you’ll be the first to know!

    Second time lucky: fingers crossed!

    I am very grateful to Ian for allowing me to test the 10 x 42 EL Range. I now know why he spent so much money to acquire one!

     

    Neil English’s new book, The ShortTube 80: A User’s Guide (267 pages), will soon be published by Springer Nature.

     

     

     

    De Fideli.