In this up-and-coming review I’ll be offering my thoughts on the Canon 10 x 30 IS II image stabilised binocular.

Tune in soon for full details…….

De Fideli.

In this blog, I’ll be test driving the Kowa YF II 8 x 30 binocular.

Tune in soon for full details….

De Fideli.

In this new blog I’ll be sharing my experiences as an astronomer who took up birding only a few years ago, as well as offering advice to beginners.

Tune in soon for details……..

De Fideli.

ISBN: 978-3031447099

523 Pages

Foreword by Holger Merlitz, author of The Binocular Handbook

Price: £20.84(UK)/$32.99(US)

Available Now

Dear Reader,

My new book on binoculars is ready for purchase from Amazon and all good booksellers. Below is a list of the chapters presented in the book.

I hope that you will support me in my work.

Sincerely,

Neil English

Preamble

Regarding the Obserwerk SE 8 x 32 ED

SN: 232161

Sunday September 10 2023

Dear Mr. Busarow,

After reviewing and continuing to use the 8 x 32 SE for a further seven months, I am more impressed than ever with this instrument. I’m not at all surprised that it has garnered more than 10,000 views on Birdforum alone, and an even greater number of visits on my website.  As detailed in my original review, I showcased many terrific features of this instrument which I will summarise as follows:

1. Exceptional blackening around the eyepieces with near perfect exit pupils
2. Complete lack of any internal reflections or diffraction spikes when directed at a bright artificial light source
3. Exceptional colour correction from the small 32mm objectives
4. Exceptional glare suppression
5. Sensibly perfect images within its very large sweet spot
6. Excellent edge-of-field performance despite its lack of field flattening optics
7. Superb handling in all weather conditions
8. Exceptionally well protected objective lenses

I’ve already commented that its sharpness and colour correction are superior to the highly rated Nikon E II 8 x 30, but its optical and ergonomic excellence has also been noted by a number of other experienced observers including the Irish birder, ‘Sancho,’ who compared it to his Zeiss TFL 8 x 32 and, based on subsequent field testing, now uses it as his ‘favourite all-round’ birding instrument.  I would like to remind you of his posts here:

My Oberwerk SE 8×32 arrived today. I haven’t had much chance to “test” it, and in any case a birding bino needs to be tested over a few weeks while actually birding. Also, I am non-technical, so anything I say is “amateur user” opinion only, applying only to my eyes. I agree wholeheartedly with everything Dipperdapper says in the excellent review. Total cost to my door (in Ireland) was 368 euro, inclusive of 68 euro customs charges, plus postage. Communication and tracking details from Kevin in Oberwerk was excellent. At first, I was dismayed when I lifted the box…it felt heavy. But when I removed the packaging, and held the binos in my hand, they didn’t actually feel that heavy because the ergos and balance are excellent. Not unlike my Nikon SE 10×42, but about 50g heavier. The Oberwerk certainly is a tough, tank-like bino, feels very solid and durable. I like the longer objective barrels because I can get two fingers around them, as with the SE 10×42, and I find this helps further with stability. The objectives are deeply recessed, another feature I like because I presume they are more protected from stray light or damage. The focus wheel is stiffer than I would like, but I reckon this is the price you pay for a waterproof porro, like the Habicht 8×30. Although it is a wide wheel (see OPs photos), I find it a little difficult to get my fingers to it, and prefer the position of the FW on the Nikon 10×42. (OTOH, the diopter adjuster is on the right ocular, where the Binocular God intended….easy to adjust, but also firm enough to stay put). In any case the focusser has no play and turns smoothly. Eyecups twist in and out and have four positions. The bino came with a strap for the case, plus two straps for the bino…a lighter “stretchy” neoprene one for comfort, or a tougher fabric-type one. Try as I might, I could induce no CA, even looking against bare tree branches against a bright, high-cloud Irish February sky. In this it was the equal of my Zeiss TFL 8×32, which is excellent. The FOV (8.2 degrees) is similar, and to be honest it was sharp across most of the field, to the extent that to find any softness at all, I almost have to stick my eyeball into the bino and search sideways! In other words, the field-flattener question is a non-issue. I tried to induce flare/glare, and couldn’t manage that either, even while looking as close to the lightly-clouded sun as was possible without endangering my eyesight. I have no idea how to “measure” light transmission, but it seems plenty bright, not quite as bright as my TFL 8×32 but that’s unsurprising. I’m going to stick my neck out a bit here and say that I think the sharpness/constrast/pop (I don’t know how to separate these “concepts”) might be a little ahead of the TFL. However, this may be just because of today’s conditions, or I may be suffering from “new-bino enthusiasm”….it needs a bit more study out in the field, in different lighting conditions. The warranty is two years, but it feels like a bino that will be used by my as yet non-existent grandchildren. An interesting feature is that in the plain black box (thank you Oberwerk, no expensive fancy boxes!), there is a card headed “Quality Checklist”, with Date, Sale, SN etc., and all the features ticked off (under the headings Appearance, Mechanical, Alignment/Collimation, Resolution) and initialled “KGB” (whom I presume is Kevin rather than the defunct Soviet body). I’ll take these out and about over the next few weeks, and play with them a bit more, but I think they are a pretty stunning binocular at any price, and for 368 euro delivered a no-brainer, unless you favour roofs and very light binos.

Source: Birdforum link post #17

Furthermore, Sancho followed up with this post some months later:

Hi just reporting back on the Oberwerk SE 8×32, after four months of use. You know how it is, you never “really” know until you’ve used binos in the field in various conditions. I have to say these have become my favourite “all-rounder, grab n’go” binoculars, and my closet contains original SEs and some big European badges. I thought early on there was a bit of “play” in the focus, but there isn’t, it just focusses at different speeds as you turn the dial (if that makes sense). It is the best bino I have at suppressing CA and stray light, and the image has the punch and contrast that reminds me of my old (sadly sold) Nikon EDG 8×42. I love the stereopsis (3D?) effect of porros, so that’s a plus for me. I’m sorry I don’t have the technical vocabulary for talking about optics; I just love these and am thinking of buying the Oberwerk SE 10×42 to complement them.

Source: Birdforum link post #117

Another experienced observer, ‘Paultricounty,’ also offered his opinion on the 8 x 32 SE:

“These are bright and sharp binoculars. I’m going to get in trouble here with some Nikon guys, but they are brighter and at least as sharp as the Nikon SE’s. They’re more neutral in color than the Nikons and has a much wider field of view. There is no field flattener like the Nikons , so they’re not sharp to the edge. It’s a very usable FOV with fall off starting at around 75% , but no mushy edges like the Kowa BDII 6.5 and 8x and some other MIC bins. Contrast is as good as the Nikon and I couldn’t see the slightest amount of CA, clearly superior to the Nikon in that area.”

Source: Birdforum link post #83

Swiss binocular enthusiast Pinac, had this to say about the same instrument on the Oberwerk website:

I ordered one online at Oberwerk in Dayton OH on a Thu midday, Oberwerk dispatched the same day, and I got the SE at my home in Switzerland after 3 business days – not bad (for Oberwerk customer service and UPS)! I had been forewarned by the various reviewers that the SE is quite big and heavy for a 8×32 – it is indeed, but build quality and finish are excellent, and ergonomics are superb, the bino fits snugly into my hands, a joy to use. The immediate impression is that for a 250 $ bino, the optics are really good.

My sample actually magnifies 8.2 x. The measured RFOV and AFOV values are a bit narrower than specified by Oberwerk, but still very nice.

Plenty of eye relief; spectacle wearers should be fine.

Nice extra travel of the focus wheel of ca. 5 dpt beyond the infinity position.

Given that the number of available good 8×30 / 8×32 porro binos is continually shrinking, this is a very welcome additon to the binoculars market, not only for porro enthusiasts.

Source: Oberwerk Website Review# 2

And yet another review from a gentleman named Noah Lawes, who compared it to his Leica BN 8 x 42:

I’m extremely impressed with the 8×32 SE. It provides a beautiful, sharp, sparkling view. It compares favorably with my Leica BN 8×42, and it’s even better in some ways, including CA control, ergonomics, and handheld stability (especially when using the “hat trick” resting the bill of a cap on the prism housings. I’m working on a longer review which I plan to post on one of the forums, but for now, suffice it to say that I think this is a great binocular in absolute terms, and it’s just amazing that you can get it for $250.

Source: Oberwerk Website Review#4

It was also very favourably reviewed by the experienced Italian binocular enthusiast, Piergiovanni Salimbeni, who stated that its performance was similar to roof prism models costing €1K. Be sure also to check out the extensive video footage he captured through the instrument on his accompanying YouTube presentation.

Having said all that, I must report one additional observation regarding the instrument’s field of view. It was after comparing it to the Oberwerk Sport ED 8 x 42 that I noted its smaller field of view in comparison. Indeed, I conducted a star drift measurement and found its field of view to be 7.48 angular degrees, which is actually the same as the Nikon SE 8 x 32. Curiously, this was also noted by CNer Rustler 46 in this link.

I fixed the problem I had with the wandering dioptre, simply by securing my preferred position with a drop of Loctite superglue – problem solved!

Finally, I suggest a few improvements to the instrument:

1. Reduce the overall weight of the chassis by housing the optics in a polycarbonate body. Better still, a magnesium alloy chassis would offer greater ruggedness and a reduced overall weight. These days, magnesium alloy is not confined to high-end models but is now being offered even on budget-priced instruments.
2. The focus wheel could be tuned better. Some owners have complained that there is some slack in the focuser, while others have noted its overly stiff tension. Improving this important ergonomic feature will greatly improve its enjoyability.

Please don’t be discouraged concerning the undeserved attacks Oberwerk has endured regarding its Chinese manufacture. Is not China a sovereign nation, just like all the other nations under the sun? Does it not have people? I note that most of the negativity came from folk who never experienced the instrument first-hand. Indeed, I suspect from the sheer volume of views that many of these dissenters actually ended up secretly purchasing the instrument lol!

In summary, it’s no exaggeration that the Oberwerk SE 8 x 32 is destined to become one of the great 32mm binoculars of our time. It’s all the more remarkable that you were able to bring it to market at such an attractive price point, which resonates well with my key objective to provide the reader with genuine bargains in today’s market in order to grow this wonderful hobby worldwide.

I wish you continued success with this amazing product!

Sincerely,

Neil English PhD.

Author of the new book, Choosing & Using Binoculars: A Guide for Stargazers, Birders & Outdoor Enthusiasts, which will soon be published by Springer Nature.

De Fideli.

Binoculars of any size benefit from stabilisation.

Could the Oberwerk Series 2000 heavy duty Monopod with trigger-grip head be the ultimate in stabilised viewing comfort?

Tune in soon for full details……..

De Fideli.

The Opticron Adventurer T WP 6.5 x 32.

A Work Commenced June 12 2022

Preamble

Product: Opticron Adventurer T WP 6.5 x 32

Country of Manufacture: China

Chassis Material: Rubberised Aluminium & Polycarbonate 

Exit Pupil: 4.9mm

Eye Relief: 18mm

Field of View: 161m@1000m(9.2 angular degrees)

Coatings: Fully Multicoated on all glass surfaces

Prisms: Porro BAK4

ED Glass: No

Close Focus: 3m advertised, 2.56m measured

Dioptre Compensation: +/- 4.0

Waterproof: Yes

Nitrogen Purged: No

Tripod Mountable: Yes

Accessories: tetherable rubber objective lens caps, ocular caps, padded neck strap, soft carrying case, microfibre lens cleaning cloth, warranty card & instruction manual.

Weight: 549g advertised, 556g measured

Warranty: 2 Years

Dimensions LxWxD (cm): 10.9 x 16.9 x 5.0

Price(UK): £65.21

Recently I put the Opticron Adventurer T WP 8 x 32 through its paces. This neat little porro prism binocular greatly exceeded my expectations, based on its excellent price to performance ratio. But I was keen also to test drive its lower power sibling, the Opticron Adventurer T WP 6.5 x 32. So I ordered up a unit from Amazon and spent a couple of weeks using it in a variety of environments. Since many of the basic features on both the 8 x 32 and the 6.5 x 32 are identical, it provided a good opportunity to investigate a phenomenon known as depth of field, and the factors which might govern its behaviour, which I shall elaborate on shortly. For now, I want to briefly summarise my findings of the 6.5 x 32 in relation to the 8x glass in the same series.

The Opticron Adventurer T WP 8 x 32 (top) compared with the 6.5 x 32 (bottom).

Like the 8 x 32 model, the 6.5x glass showed excellent control of internal reflections, diffused light and diffraction spikes(i.e. none seen). It was extremely clean, as judged by my Iphone 7 torch test.

Collimation was good as tested under the stars and also by checking a horizontal electricity cable in the distance.

Having a look at the exit pupils, I noted only slight truncation in the left barrel, but in general, the results were very good:

Left exit pupil shows slight truncation.

Right exit pupil shows nice circular geometry.

The first big surprise for me was its much superior glare suppression compared with the 8 x 32 model. For some reason that still escapes me, the 6.5x produced noticeably higher contrast images than its 8x sibling. I can only surmise that newer coatings were applied to these units at some point. Veiling glare was also much better controlled in the 6.5x unit. Eye relief is good: I was able to image the entire field with my glasses by rolling down the rubber eyecups, but it’s a fairly tight squeeze!

Close focus was measured at just over 2.5m, considerably better than the advertised 3m setting. The 6.5 x 32 delivers a huge field of view – fully 9.2 angular degrees! The sweet spot is quite large too, remaining very sharp in the inner 60 per cent or so of the field .After that, mild field curvature sets in, becoming progressively more severe as one approaches the field edges. To my eye, about 75  per cent of the field was acceptably sharp, with more pronounced blurring occurring in the last 25 per cent before hitting the field stops. Sometimes I would notice a ‘fish bowl’ effect while panning large swathes of landscape. The image is very bright; noticeably brighter than the 8x glass in fact, especially in low light conditions, at and after sunset. Colour correction is excellent in the centre, but does show a bit of lateral colour as the eyes are moved off axis, but it was no more than I’ve seen in instruments costing ten times its retail cost. In terms of colour balance, I judged the image as quite neutral.

The image through the Adventurer T WP 6.5 x 32 is very stable and quite immersive. I can easily understand why an instrument like this would be ideal for a younger individual or an older observer wishing to minimise image shake while glassing. For me though, I felt the 6.5x lacked those little details I’ve come to pick up more easily in 8x and 10x instruments. In other words, it lacked a little bit of reach. But that’s an entirely personal judgement and your mileage may vary.

Depth of Field & Stereoptic Comparisons Between the 8 x 32 and 6.5 x 32 Models

Comparing the two instruments on an open landscape in bright sunlight, I judged the image plasticity(3D effect) to be noticeably more pronounced in the 8x model. This was in keeping with my previous study on stereopsis which can be seen in this link. Indeed, the only two factors which influence image plasticity are the IPD, the separation between the objectives and the magnification, increasing linearly as these variables increase.

The opposite was true when I made some depth of field measurements, that is, when focused at infinity, how close could I keep an object focused sharply in the foreground. Borrowing my son’s laser rangefinder, and being careful to only image objects in the centre of the field to avoid the spurious effects of field curvature creeping in at the bottom of the field(which gives the impression of tightening up the focus at closer ranges), I measured the close focus at infinity of the 6.5x glass to be 33.9 yards, while that of the 8x glass gave a result of 44 yards.

So depth of field increases as magnification decreases. The question remains though, how does magnification scale with this phenomenon? To what power? And do any other factors determine the outcome?

It would be nice to know.

This is a rather complex and interesting question for sure, but I did find a reliable source that could give me a head start. Way back in 2004, a German professor of computational physics, Dr Holger Merlitz, based at the Leibniz Institute for Polymer Research, Dresden, posted an interesting communication in Cloudynights Binocular forum, where he adopted a very interesting quantitative approach to this question. I will quote the relevant part here for interest:

Hello Jean-Charles,

Your results on DOF for a binocular is in agreement with whatever I was able to figure out so far. In fact, magnification and (effective) exit pupil appear to be the dominating parameters. Here, ‘effective’ means the smaller of both, the observer’s eye-pupils and the exit pupil. I must admit that not all aspects are clear to me. The following approach to analyse this problem was suggested by Walter E. Schoen on a German discussion board:

The thin-lens equation

1/F = 1/G + 1/B

relates the distance of the object to be observed (G) with the focal length (F) and the distance of its image (B). A telescope is essentially made of two lenses, and the above relation is valid for both of them, the objective, and the ocular, for which we shall write

1/f = 1/b + 1/g

Now we assume that the binocular is focused to infinity. This means that the ocular is positioned in a way that the focal plane of the objective is on top of the focal plane of the ocular. Each object with large distance produces a sharp image in this particular plane, and the image ‘B’ of the objective coincides with the object ‘g’ of the ocular. Now we assume the object is coming closer. Its image ‘B’ is therefore shifting away from this plane, and since we keep the telescope focused on infinity, the ocular’s image ‘b’ of the ‘object ‘B’ becomes unsharp. One approach is to calculate the distance, to which the eye has to focus in order to get this image ‘b’ back into focus. The reciprocal value of this distance is the diopter-value the eye has to accommodate. With some arithmetic, and using V = F/f (magnification) and f+F = g+B = distance between objective and ocular one can obtain

b = G/Vˆ2 – f – f/V

(actually, when I tried to verify this relation, I got the opposite sign, but, being no professional, I may have messed up some conventions used for optical computations).

The result he got seemed to suggest that the main factor determining depth of field is indeed magnification. However, Dr Merlitz didn’t flesh out the details of how he arrived at this result.

Trust but verify.

So I had a go this afternoon and was able to derive the same formula, the details of which are reproduced below in my own handwriting:

So the result appears to indicate that depth of field in binoculars scales as 1/v^2, and this appears to be the predominant factor determining this effect. Incidentally, it also agrees with the findings in an article published on binoculars on Wikipedia, though no reference is given, and I always take such sources with a pinch of salt:

With increasing magnification the depth of field – the distance between the nearest and the farthest objects that are in acceptably sharp focus in an image – decreases. The depth of field reduces quadratic with the magnification, so compared to 7× binoculars, 10× binoculars offer about half (7² ÷ 10² = 0.49) the depth of field. However, not related to the binoculars optical system, the user perceived practical depth of field or depth of acceptable view performance is also dependent on the accommodation ability (accommodation ability varies from person to person and decreases significantly with age) and light conditions dependent effective pupil size or diameter of the user’s eyes.

Thus, the increase in the depth of field of the 6.5x glass compared with the 8x instrument should be about 8^2/6.5^2 or 1.51. Comparing this result to the numbers I measured, I get 44^2/33.9^2 = 1.68.

Not bad at all!

Of course, other inter-individual factors may also contribute to greater or less perceived depth of field, when two different binoculars of the same magnification are employed, such as accommodation, field curvature, or the size of the exit pupil etc.

Conclusions & Recommendations

The Opticron Adventurer T WP 6.5 x 32 is an excellent bargain for the rock bottom price paid. In keeping with the results reported by the reviewer showcased in the preamble above, it performs very well indeed, and should delight the owner with sharp, contrast-rich details in a very impressive and immersive field of view. Its minimum IPD of 53mm will make it especially attractive to those who have smaller faces, and the ultra-stable views at 6.5x will likely delight individuals who suffer from significant handshake.

Highly Recommended!

Dr Neil English is the author of seven books in amateur and professional astronomy. His 8th title, Choosing Binoculars: A Guide for Stargazers, Birders and Outdoor Enthusiasts, will be published sometime in late 2023 by Springer Nature.

De Fideli.

The GPO Passion ED 10 x 32 package.

A Work Commenced December 18 2021

Preamble 

Instrument: German Precision Optics(GPO) Passion ED 10 x 32

Country of Manufacture: China

Field of View: 105m@1000m(6.0 angular degrees)

Exit Pupil: 3.2mm

Eye Relief: 15mm

Chassis: Rubber armoured magnesium alloy, machined aluminium eyecups

Close Focus: 2.5m advertised, 1.92m measured

Dioptre Compensation: +/- 2.5

Nitrogen Purged: Yes

Waterproof: Yes(1m un-stated time)

Coatings: Fully broadband multi-coated, phase and dielectric coatings applied to Schmidt Pechan roof prisms

ED Glass: Yes

Light Transmission: 90%

Tripod Mountable: Yes

Weight: 500g advertised,  509g measured

Dimensions: L/W 11.8/11.8cm

Accessories: cleaning cloth, hard case, neoprene neck strap, hard case strap, objective covers, ocular covers

Warranty: 10 years

Price: £352.99(UK)

In a previous blog, I reviewed the magnificent GPO Passion HD 10 x 42, one of the flagship models from the relatively new firm, German Precision Optics. For the money, I felt it was an excellent bargain, especially when compared to significantly more expensive models from Zeiss, Leica and Swarovski. Gone are the days when you have to shell out several grand to get a world class binocular, and in my opinion, GPO are definitely leading the way in this regard.

But having enjoyed the instrument for a couple of weeks, reality began to bite. As I’ve remarked before, the 42mm format is not my favourite. It has nothing to do with optics or ergonomics. It’s about weight. You see, I’ve come to strongly favour smaller formats. I already own and frequently use a world-class pocket binocular, the Leica Ultravid BR 8 x 20, but my experiences with larger binoculars convinced me that an optimum size for me would come from the compact class of binoculars, with apertures in the 30-35mm size class. Such instruments are easier to hold, easier to view through, and have more light gathering power. But I was also on the look out for a 10x instrument, to afford greater reach for my glassing targets, especially birds. While I’ve enjoyed some really high quality 10 x 25 pocket glasses in the past, their smaller objectives let in less light – an important parameter when glassing in shady areas during daylight hours, and especially for discerning subtle colour tones.

Unfortunately, GPO did not offer a smaller model in their flagship HD range, but they did have a 10 x 32 model from their more economical Passion ED line. After doing some research on this model(see the Preamble link above), I decided to pull the trigger and ordered one up for testing; enter the GPO Passion ED 10 x 32.

The GPO Passion ED 10 x 32 and its high quality carry case.

First Impressions

Costing less than half the price of the larger 10 x 42 HD model, the GPO Passion ED 10 x 32 package arrived with all of the same great quality accessories that delighted me in the larger HD binocular: I received the same neck strap, a smaller clamshell case, snugly fitting rain guard and objective lens covers, GPO-branded microfibre lens cleaning cloth, instruction manual and warranty card. It arrived in the same high quality presentation box as the larger HD model, with its unique serial number etched into the underside of the binocular and on the outside of the box. Very neat!

The GPO Passion ED 10x 32 has the same excellent build quality as the larger HD models.

Picking up the binocular and holding it, I was chuffed to see how well it fitted my hands. The narrow, single bridge allowed me to wrap my fingers round the barrels better than any other 30-32mm model I’ve previously handled. And while the instrument has a lovely, solid feel about it, with its sturdy magnesium alloy chassis, I was very reassured by its considerably lower weight; just 500g as opposed to ~ 850g for the larger, HD instrument.

The GPO Passion ED 10 x 32 fits perfectly in my hands!

The central hinge is nice and stiff, making it difficult to change the IPD on the fly. I like that. The binocular has a rather oversized central focus wheel, just like the heavier HD model, and I was relieved to see that it moved very easily and smoothly, with just one finger. The professionally machined aluminium eyecups are, in my opinion, even more impressive on the Passion ED model than the HD, rigidly locking into place with one intermediate click stop. The immaculately applied rubber armouring has two textures, just like the HD, a roughly textured side armouring and a silky smooth substrate covering the inside of the barrels.

All in all, very impressive!

Ergonomics

The GPO Passion ED shares many of the high quality ergonomic features built into the more expensive HD models. The ocular and objective antireflection coatings are immaculately applied and have a fetching magenta hue when observed in broad daylight. Unlike the HD models however, they do not have the hydrophobic coatings – an acceptable sacrifice, and then some.

Ocular lens end of the GPO Passion ED 10 x 32.

The objective lenses are recessed to an extent I’ve not seen before on any other compact model I’ve had the pleasure of using. I measured it at about 9mm! Why so deep? Well, it could be to protect those objectives from the vagaries of the weather; rain, wind, and stray light etc, or maybe partially compensating for the lack of hydrophobic coatings on the glass? Whatever the precise reason, I liked it!

The beautiful magenta coloured antireflection coatings on the Passion ED are immaculately applied, and note the exceptionally deeply recessed objective lenses!

The eyecups are beautifully designed; absolutely world class! They extend upwards with one intermediate position between fully retracted and fully extended, and lock into place rigidly with a reassuring ‘click.’ This is one binocular you can safely store inside its case with the eyecups fully extended for quicker deployment. They ain’t gonna budge!

Eye relief proved perfect for me, as I don’t use eye glasses, but I think the stated value of 15mm might be a bit optimistic, as I was not easily able to observe the full field of view keeping the eyecups down and wearing my varifocals.

The beautifully machined aluminium eyecups are world class, clicking into place with absolute rigidity.

Unlike the more expensive HD models which have a centre-locking dioptre adjustment, the Passion ED presents a more cost-effective solution by returning it to under the right ocular lens. While adjusting it, I noted its excellent rigidity, rendering it very resistant to accidentally moving while in the field. I felt it was a very acceptable compromise. Furthermore, the + and – settings are clearly marked, and so it’s very easy to memorise its optimal positioning should the instrument be used by others.

The oversized focus wheel is very easy to access and manoeuvre using one finger. It has a very grippy, texturized rubber overcoat, identical in fact to the more expensive HD models. Taking just over one complete turn to go from one extreme of its travel to the other, I would rate its speed as very fast; a good thing in my opinion, as it will be used primarily for birding, where big changes in focus position are often required following a mobile avian target. Motions are very smooth though, but I did notice a very small bit of play with it; similar in fact to focus wheel on the Leica Trinovid HD 8 x 32 I used and enjoyed a while back. Here the HD model came out better in my opinion, as I was unable to detect any play whatsoever with the 10 x 42.

I was most highly impressed with the way the binocular felt in my hands though. In truth, I don’t recall enjoying wrapping my medium sized hands around the barrels as much as on any other compact binocular I’ve tested. I reckon that this is attributed to the narrow bridge, which exposes those long, slender barrels. It’s simply a joy to hold, perfectly stable and always a thrill to bring to my eyes!

All in all, the build quality and handling of the Passion ED 10 x 32 are absolutely unrivalled in this moderate price class. GPO has clearly gone well beyond the call of duty in the design and execution of these new, highly-advanced compact binoculars!

Optics

The GPO Passion ED 10 x 32 came perfectly collimated. I was able to ascertain this by carefully focusing the binocular on the bright star Capella and then moving the right eye dioptre to the end of its natural travel. The perfectly focused star from the left barrel was found right in the centre of the defocused star diffraction pattern.

The lady reviewing the 10 x 32 in the Preamble to this review stated that the binocular had no issues with internal reflections and stray light and I was able to affirm this in the 10 x 32 I received. The image of an intensely bright beam of light from my IPhone torch was clean and devoid of diffraction spikes.

The exit pupils are nice and round and have little in the way of light leaks immediately around the pupil; a very good result but not quite in the same league as those found on the more expensive Passion HD 10 x 42.

Left eye pupil.

Right eye pupil.

In broad daylight, the images served up by the GPO Passion ED are very impressive! It is bright and very sharp across the entire field, with very little in the way of distortion even at the field stops. Like the Passion HD model, it enjoys a very decisive snap to focus on whatever target I turn it on. The small exit pupil ensures that the best part of your eye does all the imaging. Colours are vivid and natural but to my eye it has a slightly warm tone, with greens and browns coming through very strongly. Contrast is very good but not quite in the same class as the GPO Passion HD 10x 42 I tested it against. Glare suppression was also impressive. Comparing it to my control binocular – a Barr & Stroud Series 5 8x 42 ED – which exhibits excellent control of all types of glare, including veiling glare, the little Passion ED proved to be slightly superior to it. However, it was not quite as good in this capacity as the GPO 10 x 42 HD model, which exhibits the best control of glare that I have personally witnessed in any binocular.

Close focus is considerably better than I had expected. The accompanying user manual claimed 2.5m for this model, but I measured it at only 1.92m!

Colour correction in the GPO Passion ED 10 x 32 is very impressive! Pointing the binocular into the branches of a leafless tree against a bright overcast sky, the centre of the image is completely devoid of it, and even off axis, I could only coax the merest trace and only near the field stops. Returning to testing the binocular under the stars, I was able to verify just how well corrected the field of view is. Stars remain nice pinpoints nearly all the way to the edges. I attribute this excellent result to GPO’s optical engineers’ choice of field size. 6 degrees is not large by modern standards so it’s easier to achieve optical excellence using standard eyepiece designs. More on this a little later.

Venturing out on a freezing, misty December night to observe the full Moon, the GPO Passion ED 10 x 32 threw up a beautiful image. It was clean and sharp and contrasty. Secondary spectrum was non existent over the vast majority of the field, with only the extreme edges showing some weak lateral colour. Field illumination was also excellent, as with the 10 x 42 HD, with very little in the way of brightness drop off as the bright silvery orb was moved from the centre to the edge of the field. I also judged field distortion to be excellent in these tests too. The Moon remains razor sharp across most of the field, and only shows slight defocus at the field stops. Indeed, it was very comparable to the results I got with my optically excellent Leica Ultravid 8 x 20 in this regard.

Complementary instruments.

These are excellent results, and quite in keeping with the comments made by the lady from Optics Trade, as revealed in the Preamble video linked to at the beginning of the review. Indeed, these results place the GPO Passion ED in the top tier optically. Its colour correction was notably better than the Leica Trinovid HD 8 x 32, and I felt its sharpness and contrast were perhaps a shade better too. I’m confident that this 10 x 32 ED could hold its own against top-rated compact binoculars up to twice its retail value or more.

Notes from the Field & Concluding Comments

The view through the GPO Passion ED 10 x 32 is very stable and immersive. On paper a field of view of 105m@1000m might seem restrictive but in practice you never get that impression. There are no blackouts, rolling ball effects or any other issues common to compact models sporting wider fields of view with field flatteners. This makes panning observations particularly pleasurable with this instrument. To be honest, I suspected that this would have been the case after I had put the Passion HD 10 x 42 through its paces. Indeed I would hazard a guess that both binocular lines – the HD and ED – have substantially similar optical designs. As an experienced glasser, I have no abiding interest in very large fields of view. Indeed, I tend to think of those wide angle binoculars as rather distracting and more suited to beginners than more seasoned observers. I’m interested in vignettes not vistas.

Goldilocks Binocular.

So there you have it! The GPO Passion ED 10 x 32 is, for me, a Goldilocks binocular, serving my purposes perfectly and fitting my hands like a tailor-made glove. It pays to mention that GPO also market a 8 x 32 with a wider field of view, and two 42mm models with powers of 8x and 10x; so something for everyone! Check them out as soon as you can. You’ll not be disappointed!

Dr Neil English has some exciting news to reveal early in the new year. For now, he’d like to wish all his readers a Very Happy Christmas!

De Fideli.

Plotina: the author’s modified 130mm f/5 Newtonian reflector, with a Vixen Erecting Adaptor and two simple Plossl eyepieces used in the investigation.

A Work Commenced October 3 2021

In this blog, I’ll be demonstrating the potential of a small Newtonian reflector operating in spotting ‘scope mode. This follows on from a previous blog I conducted to find a suitable optical device that would give fully erected and correct left-right orientation, just like a conventional spotting scope.

First, a few words of introduction about the telescope. It’s a 130mm f/5 SkyWatcher Newtonian reflector, so has a focal length of 650mm. Because of its open-tube design, the instrument is surprisingly light; just 3.8 kilos(8.4 pounds) and 4.1 kg (9 pounds) with the mounting bracket attached. It acclimates fully in 30-40 minutes, even when taken from a warm indoors environment to the cold of a Winter’s day. But such thorough cooling is only necessary to coax the highest powers out of the instrument.

The instrument has mirrors treated with state-of-the-art Hilux coatings(applied by Orion Optics, UK), increasing its overall reflectivity to 97 per cent. The primary mirror is the original one supplied by SkyWatcher, while the secondary flat mirror was upgraded with an Orion Optics UK secondary, having a flatter surface and smaller semi-major diameter of 35mm. This provides a small 26.9 per cent central obstruction. This size of central obstruction is significantly smaller than a Maksutov or Schmidt Cassegrain (SCT) of the same aperture. Unlike the popular Maksutov, the 130mm Newtonian(aka Plotina), can deliver a significantly lower magnification. For example, using a 32mm Skywatcher Plossl, it delivers a power of just 20x and using another Plossl of focal length 10mm, the telescope provides an amplification of 65x. I used these two eyepieces to demonstrate the spotting scope potential of the Newtonian, as many conventional spotters provide magnifications in this range(20-65x), corresponding to exit pupils of 4.7 and 2mm, respectively.

The contrast transfer is provided by subtracting the aperture of the secondary from the primary(130-35 = 95mm), thus one can expect a degree of contrast equivalent to a 95mm apochromatic refractor. Its light gathering power and resolution(0.89″) are significantly higher than a 95mm refractor, however. This has been borne out in several years of observations of lunar, planetary, double star and deep sky observing. The reader will find several other blogs I have published on this instrument in the past by clicking on the ‘Telescopes’ link on the home page.

The Erecting Adapter: Purchased for £80, the Vixen erecting adapter is a rather long appendage but delivers an upright image with the correct left-right orientation, just like a conventional spotting ‘scope. The lenses in the adapter are fully multi-coated and truncates the field a little when employing longer focal length eyepieces. You simply insert the desired eyepiece into the adapter, focus the ‘scope, and you’re off to the races!

Plotina, with the erecting adapter attached.

The instrument was used in broad daylight outside on a cool, breezy autumnal day, between heavy rain showers. It was mounted on a simple non motorised alt-azimuth(Vixen Porta II). The instrument is equipped with Bob’s Knobs screws for quick and easy collimation using a Hotech laser collimator. Alignment of the optics takes just a few seconds to get precise alignment of the secondary and primary mirrors. All of the images were taken simply by pointing my Iphone 7 into the eyepiece and taking single images. The pictures presented here are the highest resolution I can load onto this website( ~200-750KB), so are not the highest quality that I can potentially show. All the images are completely unmodified, apart from cropping. All distances quoted were measured with a laser range finder, and all the images were taken on the same breezy afternoon of October 3 2021.

Results:

Image 1: Shows a TV satellite dish at a power of 20x located at distance of 27 yards:

Image 2 shows some autumn leaves at 20x and located at a distance of 18.9 yards

Image 3 shows the branches of a tree at 20x located 43.1 yards from the scope:

Image 4 shows a hill top located at about 2 km distance at 65x

Discussion:

I am very encouraged by the results I obtained this afternoon. Irrespective of the scepticism of arm chair theorists, the images speak for themselves! The instrument provides very nice, high contrast and colour pure renditions of a variety of targets. Chromatic aberration is particularly well controlled, as expected, given that the Newtonian is a truly apochromatic optical system, though some secondary spectrum is introduced by the eyepieces chosen. In addition, higher quality eyepieces will give better off-axis performance, and because those oculars are inter-changeable, a greater range of  magnifications can be explored. Visually, the images are considerably better when examined with the naked eye. The reader will note that these magnifications are somewhat pedestrian for such a large telescope. Visually, much higher magnifications can be utilised profitably. And although the formidable resolving power of the instrument is clearly in evidence, the images could be improved further by employing a higher quality phone camera. What’s more, the images could also be processed lightly to bring out even more details.

The set up, though admittedly bulky by conventional spotting scope standards, could quite easily be erected in the field or, better still, in a hide, where it could be used to gather video footage or still images with the right equipment. Observing from indoors, through a clean window is also a distinct possibility, especially at lower powers. The instrument is not weatherproof however, owing to its open-tube design, so may be prone to dewing up but a small, battery-operated fan would extend its longevity in field use.

I believe this provides a very cost effective way(the entire apparatus set me back just a few hundred pounds) of obtaining high quality images compared with a high-end apochromatic spotter.

Food for thought!

Thanks for reading!

Dr Neil English spent most of his adult life testing and observing through telescopes of all varieties and genres. He now enjoys a new lease of life exploring the terrestrial realm during daylight hours.

De Fideli.

I will praise thee; for I am fearfully and wonderfully made: marvellous are thy works; and that my soul knoweth right well.

                                                                                              Psalm 139:14

Preamble

Oculus Historiae 1

Oculus Historiae 2

In this series of lectures, world-leading synthetic organic chemist, Professor James Tour, takes on an internet troll who claims that scientists have discovered how life got started from simple chemicals on the primordial Earth. In this series of presentations, Dr. Tour explains, in exquisite technical detail, why scientists are really clueless about how life got started.

Indeed, abiogenesis is actually impossible!

So buckle up and enjoy the ride!

Aims of the Lecture Series

An Introduction to Abiogenesis

The Primordial Soup

 Hype

Homochirality

Carbohydrates

The Building Blocks of Building Blocks

Peptides

Nucleotides

Intermediate Summary

Lipids

Chiral-Induced Spin Selectivity

Cell Construction & Assembly Problem Part 1

Cell Construction & Assembly Problem Part 2

Summary & Projections