Product Review: Opticron Aurora BGA VHD 8 x 42.

The Opticron Aurora BGA VHD 8 x 42 package.

Product: Opticron Aurora BGA VHD 8 x 42

Country of Manufacturer: Japan

Chassis Material: Magnesium Alloy

Exit Pupil: 5.25mm

Eye Relief: 20mm

Field of View: 141mm&1000m(8.1 angular degrees)

Coatings: S-H type multi-coating to all air/glass surfaces,Phase corrected prisms with Oasis prism coating

Dioptre Compensation: +/- 5

Close Focus: 1.9m advertised, 1.94m measured

Water Proof: Yes

Nitrogen Purged: Yes

ED Glass: Yes, VHD optical system incorporating field flattening technology and high quality ED glass objective system

Weight: 725g advertised, 711g measured

Dimensions: L/W/H 15.2×13.2×5.2cm

Accessories: Premium quality soft Cordura case with rainguard, neoprene bungee strap and rubber objective lens covers

Warranty: 30 years

Price(UK): £799.00

 

 

In this review, I’ll be test driving Opticron’s new flagship binocular, the Aurora BGA VHD 8 x 42.

 

Tune in soon for full details…………………….

 

De Fideli.

Product Review: Vortex Diamondback HD 10 x 32.

 

The Vortex Diamondback HD 10 x 32 package.

Preamble

 

A Work Commenced July 4 2022

 

Product: Vortex Diamondback HD 10 x 32

Country of Manufacture: China

Chassis Material: Aluminium

Exit Pupil: 3.2mm

Eye Relief: 14mm

Field of View: 113m at 1000m(6.5 angular degrees)

Coatings: Fully Broadband Multi-coated, phase correction and dielectric coatings on BaK4 prisms, Armortec anti-scratch coatings applied to outer lenses.

Dioptre Compensation: +/- 4

Close Focus: 1.8m advertised, 1.84m measured

Water Proof: Yes

Argon Purged: Yes

ED Glass: Unknown

Weight: 454g advertised, 451g measured

Dimensions: H/W 11.2/12.7 cm

Supplied Accessories: Padded neck strap, logoed hard clamshell case, tethered rubberised objective and rain guard, microfibre cloth,  instruction sheet, VIP Warranty

Price(UK): £183.92

 

The compact 30 to 35mm aperture class of binoculars has emerged as my personal favourite size. Offering a solid binocular experience in a light weight body, they are ideal for daytime use and so enjoy enormous popularity among birders, hikers and general nature enthusiasts. There was a time not so long ago when obtaining a quality optic meant forking out a sizeable amount of money, but thankfully those days are now well and truly behind us.

In a previous review(see the preamble link above), I showcased the Diamondback HD 10 x 42, discovering its many virtues, both optically and ergonomically. Here I wish to discuss my findings about its smaller sibling, the 10 x 32 model.  This is a third generation binocular, having being upgraded in 2019 with a higher quality optical system than the previous( 2016) model.

The package I received was pretty much identical to the larger 10 x 42 model, save for the inclusion of a smaller clamshell case(see the image above) which better fits the smaller frame of the 10 x 32. And just like the 10 x 42 Diamondback HD, the 10 x 32 possesses the same quality ergonomic features of its larger sibling. The lenses are fully multicoated throughout, the prisms are treated to a phase correcting coating and the use of high-reflectivity dielectric coatings ensures a high level of light transmission. of the order of 85 per cent.

Ergonomics

Though considerably smaller and less massive than its 10 x 42 sibling, the 10 x 32 Diamondback HD proved to be equally well made, possessing a smooth focusing wheel with no play or backlash, a tightly set right eye dioptre ring which maintains its position well, a pair of solidly made twist up eyecups with three positions that lock firmly into place, and all built around a very sleek and stylish aluminium alloy chassis that tips the scales at only 451g.

In field use, the instrument is easy to get your hands ’round, thanks to a decently short central bridge and barrels long enough to allow your fingers to grip the instrument with confidence. The green rubber armouring also has enough friction to prevent any slippage, even in wet weather.

Like its larger siblings, the Vortex Diamondback HD is an ergonomic delight to handle.

The ocular lenses are stated to have 14mm of eye relief. Using my eyeglasses however, I was not able to make out the entire field.

The objectives give a nice purple tinted view when viewed in bright sunlight, but they are not deeply recessed, which is not ideal for controlling stray light, dust and rain. Thankfully though, these binoculars are o-ring sealed with dry argon gas, making them fog proof and water proof, at least on paper.  In addition the outer lenses are treated to Vortex’s proprietary Armortec coatings, which provide additional protection from scratching, and the accumulation of water droplets and oil from grubby fingers.

 

The 32mm objectives on the Diamondback HD have good multi-coatings though they could be recessed a little bit more within their barrels.

The underside of the binocular has two small thumb indents, presumably to guide your hands to the ideal places to grip the instrument. In practice however, I never used them.

Note the two small thumb indents on the underside of the binocular.

All in all, this is a very nicely designed and refined binocular, with very well thought out ergonomics. Top marks to Vortex here!

Optics

I began my tests as usual, looking at an intensely bright beam of white light to see how the optics behaved. The results were excellent; there were no internal reflections or diffraction spikes and very little in the way of diffused light around backlit targets as seen from across my living room. The same was true when I looked at a bright yellow sodium vapour street lamp at night. This will be a good binocular to view illuminated objects after dark.

Next, I examined the exit pupils to test for light leaks. The results were quite good. There was little in the way of stray light immediately around the pupils, though the right ocular showed the merest sign of truncation. Some light leaks were evident further from the pupils as the images below show:

Left exit pupil.

Right eye pupil

I performed most of my optical testing during daylight and under a variety of conditions, on bright, sunny days and during fairly dull, overcast conditions. Collimation was spot on! The images served up under most conditions were quite impressive, the binocular delivering very bright, pin sharp and high-contrast images with a very neutral colour tone. To my eye, there is quite a sparkle to these Diamondback HD images, especially when viewing targets in the centre of the field under good lighting conditions. The sweet spot is very generous in the 10 x 32 Diamondback HD. Indeed, most of the field remained pleasingly sharp with some minor field curvature and pincushion distortion creeping in near the field stops. Chromatic aberration was quite well controlled too, especially for a 10x glass. I detected the merest trace on axis by examining the brilliant white plumage of a Mute Swan against a dark water background. When examining leaves strongly backlit against a bright overcast sky inside a forest, I detected some very minor lateral colour but nothing that rendered the view particularly distracting.

Another thing that impressed me about the 10 x 32 Diamondback HD image was the very generous field of view: 6.5 angular degrees. That’s way larger than the 10 x 32 GPO Passion ED I showcased some time ago, which only manages a 6 degree true field in comparison. Indeed many 10 x 42 binoculars I’ve tested in the past only managed to serve up field sizes of the order of 6.2-6.3 degrees in comparison. The larger true field of the 10 x 32 Diamondback HD renders the view more immersive and engaging. And unlike some reports I’ve read about the 8 x 32 model from this series, there was no sign of chromatic aberration of the exit pupil, which manifests itself in a colourful ‘ring of fire’ circling the field stops.

The only optical effect I found slightly distracting was glare, which shows up when the instrument is pointed toward a setting Sun, either in a clear blue sky, or when veiled behind some clouds. Mild veiling glare also manifested itself when viewing the topmost boughs of conifer trees against a bright overcast sky. Fortunately though, much of this glare can be removed simply by shading the objectives with an outstretched hand.

Notes from the Field

The Vortex Diamondback HD 10 x 32 is an enjoyable instrument to use in the great outdoors, its light weight but tough, waterproof design, adding to its charm  Close focus was measured to be 1.84m, a really good result, especially if you like looking at butterflies and other insects at close hand. Depth of field is decent for a 10x roof.  The focus wheel operates flawlessly, being neither too slow or too fast. Unlike the GPO Passion ED  10 x 32 model I tested extensively, there is no free play in the focuser. I’ve expressed some tolerance for a small amount of play in a binocular focuser in the past, but these days it has become more of an annoyance. That’s especially the case, since the Diamondback HD costs considerably less than the GPO! The HD labelling of the Diamondback is still somewhat of a mystery to me, as I’m still not sure if ED glass was employed in its design. Not that it matters that much; some of the best instruments I’ve looked through don’t use any!

Conclusions & Recommendations

The Vortex Diamondback HD 10 x 32 is a terrific little binocular. It looks and behaves like a much more expensive instrument. Its powerful magnification boost coupled to its wide and well corrected field of view create the instant impression of a quality instrument. Vortex really hit the ground running when they launched this excellent low-cost binocular range. I often wonder if a fourth generation Diamondback will someday see the light of day. Slightly better coatings and more deeply recessed objectives and/or more aggressive baffling, would go a long way to making a very good binocular great!

 

Highly recommended!

 

 

Neil English is currently writing an in-depth buyer’s guide for binocular enthusiasts. Choosing Binoculars – a Guide for Stargazers, Birders and Outdoor Enthusiasts, will be published by Springer Nature in late 2023.

 

De Fideli.

Product Review: Opticron Adventurer T WP 6.5 x 32.

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 time. 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? Does it vary inversely as the square root of magnification or the square of magnification, or is it just inverse to the magnification or some such? 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.

Product Review: Opticron SR.GA 8 x 32.

A Work Commenced May 23 2022

 

 

Product: Opticron SR.GA 8 x 32

Country of Origin: Japan

Ext Pupil: 4mm

Eye Relief: 13mm

Field of View: 145m@1000m(8.25 angular degrees)

Chassis: Rubber armoured Aluminium & Polycarbonate 

Dioptre Compensation: +/- 5.5

IPD Range: 58-72mm

Close focus: 3.7m advertised, 2.84m measured

Prism: Porro BAK4

Coatings: Proprietary  ‘N’ ty differential multi-coating

ED Glass: No

Waterproof: No

Nitrogen Purging: No

Weight: 543g

Dimensions L/W: 10.1×16.0cm

Accessories: Ocular & objective lens covers, rain guard, soft leather carry case, padded logoed neck strap, instruction manual and warranty card

Warranty: 30 years

Retail Price: £199(UK) $315(US)

 

As I write these words in May 2022, it’s getting very difficult to source good-quality porro prism binoculars, especially in the smaller, compact sizes. Over the last few decades aggressive marketing has promoted the roof prism binocular with all its innovations, but with ever increasing price tags. That’s the road I largely followed in my exploration of the binocular market, until I decided to check out a number of  porro designs from companies like Nikon and Opticron, who maintained several high-end models worth checking out. As I explained in previous blogs, it takes a lot of effort to create a roof prism binocular that can even approach the optical performance of good quality porro prism models. In this review, I’ll be demonstrating this proof of concept, by putting Opticron’s Japanese-made SR.GA 8 x 32 binocular through its paces.

Sourcing the Binocular

Perusing the Opticron UK website, I came across details about the SR.GA  8 x 32 model. Featuring a whole host of attractive features, including state-of-the art Japanese porro prim optics, a well made chassis and rubber armouring, all for an attractive retail price of £200. Incidentally, it’s available in the US for a retail price of about $315, but was discontinued as of May 2022. I contacted a member of the sales team at Opticron, Luton, and they were able to ship me out a unit. I was very excited when the package finally arrived, double boxed, with everything packed away well. What I received was the binocular inside an attractive, black leather case, together with a nice selection of high quality accessories, including a logoed neoprene neck strap, objective and ocular lens covers, a rain guard, a microfibre lens cleaning cloth, instruction manual and that all-important 30 year warranty(in the US it’s supplied with a Premier Plus Limited Lifetime warranty).

The Opticron SR.GA 8x 32 package.

Common Ancestry

The reader will note that at one time four SR.GA models were being offered by Opticron: 8 x 32, 7 x 42, 8 x 42 and 10 x 42. The larger models appear to be discontinued and I was informed that they only had limited numbers of the 8 x 32 model available. Opticron state that these were updated versions of their earlier HR models, but I also found a source claiming that the SR.GA 8 x 32 in particular is optically identical to another model which just pre-dated the HRs, that is, the Dioptron 8 x 32. Here is the source of that information dated June 2018:

Many years ago I bought a pair of Opticron 8 x 32 Dioptron binoculars. These served me well for many years until I was seduced by the lure of roof prisms and sold them – a decision I have regretted ever since. Don’t get me wrong; I love the easy handling quality and balance of my 8 x 42 roof prisms, but I have missed being able to carry a small porro prism binocular that could be slipped into a jacket pocket.
The SR.GA is a direct descendant of the Dioptron. In fact, Opticron told me that the optics and mechanical elements are exactly the same. What has been added is better multi coating of the optical elements and the rubber armour on the outside. The result is a beautifully made (still in Japan), chunky little binocular that performs as well as a modern roof prism at three times the price.
It has bright, natural colours and that 3 dimensional image you only get with a porro prism.I would agree with another reviewer that the image is sharp for about 80% of the field of view and I couldn’t detect any colour fringing when looking at back lit objects.
Negatives? Not great for using with spectacles, no waterproofing, strap is ok, but nothing special, and while the case is nicely made, it is too tight a fit if you want to quickly take out or put away the binoculars.
In summary, high quality porro prism binoculars are pretty rare these days and you wonder how long Opticron will continue to sell this range.

Source: Amazon UK

As it so happens, I recently acquired a mid-1990s Opticron Dioptron 8 x 32, and even described some of its features and operation in this previous blog. Let’s take a closer look.

Here you can see both instruments from above;

 

The Opticron SRGA 8x 32 (top) and the Dioptron 8x 32(bottom).

Both instruments have the same size field of view, that is, 8.25 angular degrees. Both are also Japanese made.

In the next picture, you can see that they have the same dimensions. The Dioptron is unarmoured, unlike the SR.GA.

The binoculars have the same dimensions as the picture above shows. The SR.GA is featured on the left, while the Dioptron is seen on the right.

I reasoned the rubber armouring would add a bit of weight, so I compared the two on a weighing scale. Sure enough, the Dioptron tipped the scales at 494g, while the SR.GA  weighed in at 543g.

The Amazon reviewer stated that the optics were identical in both models but the SR.GA had improved anti-reflection coatings. I can personally attest to these findings, as I’ve compared both in side by side tests.

In the next image, the coatings on the objectives of both binoculars are compared. The Dioptron shows a bright blue anti-reflection coating in normal daylight, while the more recent SR.GA shows much more subdued coatings, a good first sign that more light is being transmitted in the latter model.

The Dioptron(top) objective coatings reflect more light than those on the SR<GA(bottom).

Finally, you can clearly see the effects of adding the rubber armouring on the SR.GA compared with the unarmoured Dioptron. The latter is less well ‘padded out’ compared  with the former:

The armouring pads out the SR.GA (right) compared with the Dioptron(left).

And though there are small differences in the texture of the focus wheels in both instruments, I believe they are built round the same mechanism. The eyepieces are also pretty much identical in both models. In sum then, I think it’s a good bet that the SR.GA is indeed an updated version of the Dioptron 8 x 32.

Ergonomics

The SR.GA is a very finely made instrument. In the hands, it feels very solid, with the rubber armouring helping the user maintain an excellent grip. The oversized focus wheel is covered in fine rubber and is exceptionally fast, moving from close focus to just beyond infinity in less than half a turn(actually about 160 degrees). Some super fast focusers make it easy to overshoot by accident, moving past the ideal focus position too easily. This is never a problem with the SR.GA 8 x 32 though; the gearing and tension is just perfect for high speed focusing. There is no backlash or free play either. In short, this is one of the nicest focusers I have had the pleasure of using in a binocular in this size class!

The dioptre compensation ring is located under the right ocular. It’s adjusted by rotating it slowly clockwise or anti-clockwise. It’s not quite as well tensioned as the Nikon E II 8 x 30 I recently showcased, and, as a result, it does tend to wander a wee bit in field use. This can be easily remedied by wrapping a small elastic band round the ring. For me, I just remember my preferred position and make slight adjustments every now and then when required.

The eye relief on all these classic, compact porros is poor, it has to be said. It has a value of just 13mm on this model. That’s not an issue for me, as I don’t wear eyeglasses while using binoculars but those who must wear eyeglasses will find viewing the entire field problematic. I checked this by turning down the rubber eyecups. I could not image the outer part of the field while wearing eye glasses. Just like the Nikon E II, spectacle wearers will benefit from using more contoured glass lenses with high-index glass.

Just as the thick rubber armouring will help protect the instrument against knocks and light rain, the deeply recessed objective lenses also confer quite a bit of protection against aeolian-derived dust, rain and stray light.

The fully multi-coated  32mm objectives are deeply recessed to protect them from dust, rain and stray light.

All in, this a very delightful instrument and a real joy to use.

Optical Assessment: 

As always, I began my optical testing of the Opticron SR.GA 8 x 32 by turning my IPhone 7 torch up to its brightest setting and examining the images as seen visually from across my living room. The results were good. There were no diffraction spikes and only a few slight internal reflections in evidence, with only a trace of diffused light observed around the light source. Compared with the older Dioptron 8 x 32, it was a far cleaner result. Later, I turned the binocular on a bright, yellow sodium street lamp and did manage to detect some very weak internal reflections. In this capacity, it was a notch down from the excellent Nikon E II porro prism binocular previously tested.  Turning to a bright gibbous Moon low in the southeast, I was pleased to see that these internal reflections were quite well subdued. This will be a good instrument to follow the phases of the Moon with, and for observing cityscapes at night.

My next test was to photograph the light emerging from the exit pupil in both binocular barrels.

As you can see, the pupils are round and untruncated, with little in the way of light leaks around them.

Right exit pupil.

Left exit pupil.

Testing under the stars showed the binocular to be very accurately collimated. Just focus on a bright star like Vega, and defocus the right barrel image using the dioptre ring. The focused right barrel image of the star was seen very near the centre of the de-focused anulus, indicating very good alignment. I detected a modest drop in illumination as a bright gibbous Moon was moved from the centre of the field to the extreme edge, but all within design tolerances.

The  Opticron SR.GA 8 x 32 serves up a really good image during all daylight conditions. It’s bright, with excellent sharpness across about 70 per cent of its very large field(8.25 angular degrees). The outer 30 per cent of the field shows progressively more field curvature and pincushion distortion, but not to the extent that it is distracting. Contrast is excellent, as is colour saturation. I found comparing it to the older Dioptron model to be eye opening(excuse the pun). The latter image was quite yellow and less bright in comparison to the much more neutral colours served up by the SR.GA. This probably indicates that its light transmission curve as a function of visual wavelength is flatter and brighter in comparison with the Dioptron. The other thing that was noticeably improved was glare suppression while looking near a setting Sun. The SR.GA  was far superior to the Dioptron in this regard, and the same was true when testing for veiling glare. That said, the SR.GA was not quite as good as the Nikon E II 8 x 30 in similar, side-by-side tests.

Colour correction is excellent: I detected none on axis and only a trace when examining high contrast objects, like a telephone pole set against a bright, leaden sky.

As I’ve come to expect from a high-quality porro prism binocular like this, the instrument manifests vivid 3D images of the landscape over short and medium distances. Like the superlative Nikon E II I recently showcased, there is very much a sense of ‘focus and forget,’ especially when trained on targets beyond about 30m or so. I measured its close focus- 2.84m – to be significantly better than the advertised 3.7m. Just like the Nikon E II, scanning large swathes of landscape with this instrument is supremely comfortable, with no blackouts to mention and no rolling ball effect.

Serious fun

As a stargazing binocular, I enjoyed lying out on a recliner in my back garden in the wee small hours of an early May morning, scanning the summer Milky Way through Cygnus. Stars show up as lovely pinpoints of light across most of its expansive field, against a dark sky background. Though not the best instrument for binocular stargazing, it still showed me pretty views of the Coat Hanger asterism in Vulpecula, the great globular cluster M 13 in Hercules, and some lovely views of the colour contrast binocular double O^1 Cygni. This will make a rather good instrument for enjoying the up-and-coming Perseid meteor shower when truly dark skies return to our shores in early August. It has also presented some lovely, high-contrast images of the crescent Moon and earthshine, as well as tack-sharp images of crater fields and the lunar maria.

In summary, this will make an excellent general purpose instrument for my needs. Though it’s not waterproof, it’s most certainly a tough little binocular, and ergonomically is very easy and intuitive to use. I have already enjoyed many hours with this instrument, surveying the hills around my home, exploring woods and forests, rivers and ponds, and also for scanning trees and bushes for small, passerine birds.

Comparisons Between the SR.GA and the Nikon E II

One might legitimately ask why one would use the SR.GA in preference to the Nikon E II and vice versa? Optically, the reader might be surprised to learn that the views are much more similar than they are different. Both instruments have excellent central sharpness with nice big sweet spots. Both have excellent colour correction and very similar colour tones. Both have really good control of glare. If I were to nail it down, I’d just say that optically, the Nikon E II does everything that little bit better than the SR.GA. But optics are only half the story. I prefer the handling on the SR.GA. It just fits my hands that little bit more securely. I favour the super-fast and precise focuser on the SR.GA  over that accompanying the Nikon E II. Indeed, I think the Opticron makes for a better birding binocular than the Nikon for this very reason. The SR.GA also has better ‘hang’ than the E II, meaning that it sits more flatly against my chest than the Nikon wonder bino.

So, for me, it’s not really a question about which instrument I prefer. I’m a little old-fashioned and just a little bit sentimental. A cursory perusal of the literature of 20th century birders and naturalists, shows the 8 x 30 emerging as a spiriting gestalt, connecting very different people in very different circumstances, across the fields and the years. So, I count myself extremely lucky to own both and hope to use the SR.GA pretty much routinely, while the Nikon E II will be reserved for more special occasions, when the mood takes me. Indeed, I hope to write extensively about my experiences with both these neoclassical porro-prism beauties in future blogs and elsewhere…….

A Note on Storing the Instrument

Having a small, air- and watertight tub filled with desiccant is a great way to store your porros from day to day. The instrument is just placed inside the tub without any caps on so that it can be picked up and out in a matter of seconds.

While the case that accompanies the SR.GA is very nicely made, it’s a bit of a squeeze to get the instrument into and out of, especially if I want to be out the door fast. I’ve thus decided to store both my compact porros in small air-and water-tight plastic tubs. Lining the inside with a plastic bag, I have also included several sachets of activated silica gel. By activated, I mean the sachets are placed in a low power setting of a microwave oven for several minutes to drive off the absorbed water from the silica gel pellets. When the blue coloured crystals turn orange-green, you’re good to go. I’m also in the early stages of experimenting with a possible fungicide; camphor, which has well established fungus killing properties. I think the instruments might well benefit from a ‘camphor bath’ every few months or so for 7 to 10 days to curtail any fungal growth which may set in over the long term. For travel and vacation though, the black leather Opticron carry case should serve me fine.

Desiderata

It’s a great pity that quality, Japanese-made porros like these are becoming as rare as hens’ teeth. I for one have been won over by their optical and ergonomic charms and would heartily recommend them to anyone. And while great roof prism binoculars will always have their place, the world is big enough for both families. In this capacity, I have submitted a proposal to pen a brand-new literary work – Choosing & Using Binoculars –  showcasing the many and varied binoculars now available on the world’s stage, a work that will help as many people as possible make good, informed decisions on choosing and using the right model for their intended purposes. There will be plenty in it for everyone: birders, hikers, general nature enthusiasts, mariners and astronomers….and for all budgets. The proposal has now been approved and will be published as a fully-illustrated, stand-alone text by Springer Nature in late 2023.

 

I hope you will support the author in this project.

 

Thanks for reading!

 

 

De Fideli.

 

Product Review: Nikon E II 8 x 30.

The Nikon EII 8 x 30.

A Work Commenced May 14 2021

 

Preamble 1

Preamble 2

Preamble 3

 

Product: Nikon E II 8 x 30

Country of Origin: Japan

Chassis: Die Cast Magnesium Alloy 

Exit Pupil: 3.75mm

Field of View: 154m@1000m(8.8 angular degrees)

Dioptre Compensation: +/- 4

Coatings: Fully Broadband Multicoated

Prisms: Porro BAK4

Close Focus: 3m advertised, 1.96m measured

Eye Relief: 13.8mm

Waterproof: No

Nitrogen Purged: No

ED Glass: No

Weight: 575g

Dimensions L x W: 18.1 x 10.1cm

Accessories: Padded logoed neck strap, objective covers, rain guard, soft leather case, instruction manual, warranty card

European Warranty:10 Years

Retail Price: £579.99(UK)

 

 

The Japanese optics frim, Nikon, needs to introduction. For over a century, they have delighted a loyal fan base of enthusiasts with their photographic and optical innovations. Thankfully, for us binocular enthusiasts, a small part of their business is still devoted to bringing high quality instruments to the market to suit virtually everyone’s budget. In past reviews, I’ve showcased some of their better wares, such as the top-rated Nikon Monarch HG 8 x 30 roof prism binocular. But Nikon also enjoys a long tradition of manufacturing high-quality, classic porro prism binoculars and in this review, I’ll be giving my opinion on its flagship model, the Nikon E II 8 x 30.

Introduced back in 1999, the Nikon EII is offered in two models, an 8 x 30 and a larger 10 x 35. What distinguishes these units from their lower-priced econo-models are their state-of-the-art optics, very large fields of view and exceptional build quality. As you may have guessed, this kind of quality doesn’t come cheap, but I hope you’ll agree that they still represent exceptional value for money, especially when you factor in how much an equivalent roof model would cost to even approach the quality of these amazing porro prism instruments. So if you’re in any doubt about my verdict on the 8 x 30, it gets my top recommendation. What follows here are detailed notes on its ergonomics, optics and handling in the field.

The Package

The box containing the instrument looks seriously plain Jane; just simple, brown carboard. But when you prize it open, you get a very fetching soft leather case containing the instrument. All the paper documentation, including a multi-language instruction manual, warranty details etc are found at the bottom of the box. The binocular comes with a Nikon logoed plastic rain guard, and loosely fitting plastic objective covers. The high quality neck strap appears to be made from woven cotton and has a matching logo inscribed, “Nikon since 1917.”

The Nikon E II 8 x 30 package.

Binocular Ergonomics

The Nikon E II 8 x 30 is exceptionally easy to hold in my medium sized hands. It’s also very lightweight, tipping the scales at just over half a kilo.  The fit and finish is excellent, with a strong retro look, though it must be pointed out that the instrument is not rubber armoured. I suspect that this was avoided to maximise the aesthetic appeal of the binocular in order to make it look and feel like a true classic glass. Indeed, I seem to have garnered similar ideas about the Nikon Monarch HG 8 x 30; it too is lightly armoured for maximum aesthetic effect.

The dioptre setting is found under the right ocular. It moves with a fair amount of friction and holds its position very well, even after weeks of daily use.

Unlike many other classic porro prism binoculars of the past, the dioptre ring on the Nikon E II is very firm and moves only with a fair amount of torque.

The focus wheel works very smoothly, with zero play or backlash. It goes through just shy of 1.5 revolutions from one end of its focus travel to another. At times it can be challenging changing focus, from very near to very far, but in practice, once an object is located in the middle distance, only very slight adjustments are required to keep the image razor sharp all the way out to infinity.

The eyecups are made of soft rubber that seem very durable. The ocular filed lens diameter is good and large – 20mm. The cups can be folded down to accommodate eye glass wearers. Though I don’t personally wear eye glasses while glassing, I did test to see if I could see the entire field with my eyeglasses on. I can report that it could just be done, but I didn’t find the experience particularly comfortable. Those of you who must wear eye glasses would benefit from wearing more contoured spectacles with high-index glass.

The Nikon E II has rubberised eyecups that can be folded down to accommodate eye glass wearers.

The serial number of my unit is 822128, indicating a fairly recent manufacture. There has been some discussion about whether or not the anti-reflection coatings on the Nikon E II series have been improved over the years. Given Nikon’s tendency to improve their products without formal notification, I don’t see why they haven’t been modified since launching the product back in 1999.

The unit has been recently manufactured based on the serial numbering.

The ocular field lenses are large and easy to square one’s eyes up with. They are multi-coated as seen from above:

Note the large ocular field lenses, some 20mm in diameter.

The objectives are reasonably well recessed and have a beautiful magenta hue in daylight.

The beautiful and uniformly applied anti-reflection coatings on the objective lens.

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A Curious Aside:

3D Perception Differences Between Roof and Porro Prism Binoculars

Careful observers have noted a more enhanced 3D(image plasticity) effect using porro prism binoculars. Is there a basis for this effect in reality? Yes, indeed there is. To see how, read on.

Suppose we are imaging two objects along the same line of sight; one located at a distance of 10m say, and another located at 15m, as illustrated in the figure below, only with greatly exaggerated angles for the sake of clarity

For a roof prism binocular, assume that the distance between the centres of the objectives is the same as the inter-pupillary distance which is ~6.5cm (0.065m) for my eyes, so half this length, 0.0325m, represents x in the diagram above.

 

Using simple trigonometry, at 10m distance the half angle B subtended by the object in the roof prism binocular is given by

Arctan(0.0325/10) = 0.186 degrees or 11.2’

Similarly, the object located at 15m will subtend a half angle A given by

Arctan(0.0325/15) = 0.124 degrees or 7.4’

Therefore, the image plasticity is provided by the angular separation B-A = 3.8’

 

Next consider the same scenario for a porro prism binocular, just like the Nikon E II, with a spacing between the objective centres measured at ~12.5cm, so x increases to 0.0625m

 

At 10m distance angle B is given by Arctan(0.0625/10) = 0.36 degrees or 21.5’  and angle A is given by Arctan (0.0625/15) = 0.24 degrees or 14.3’

Therefore, the angular separation(Image plasticity), B-A, for the porro prism binocular is 21.5 – 14.3 = 7.2’

Thus, without considering magnification, the porro will show a much more discernible spatial difference between the objects than an equivalent roof prism model.

Notes: The more widely set one’s eyes are the greater the 3D effect manifested. So those who enjoy a wider IPD will experience this better.

The wider the separation of the objectives in the porro prism binocular, the greater the 3D effect. I would thus expect a typical 7 x 50 porro to give even more pronounced image plasticity than a little 8 x 30.

The reader will also note that as the distance to both objects is increased, the differences between the roof prism binocular and the porro will diminish. For example, similar calculations show that the same objects located at 60 and 65m, respectively, would have an angular separation of only 0.15’ in the roof prism binocular and 0.3’ in the porro prism counterpart. Since the limit of resolution of the human eye is about 1 arc minute, the differences here will be all but indistinguishable. So, we can conclude that the 3D effects of porro prism binoculars work optimally at middle distances, and all but vanish at larger distances.

The above discussion did not consider the role of magnification though. The key point here is that the binocular will magnify those small angular differences and so help the eyes to spatially distinguish the objects better. So, for example, two objects at a distance of 190m and 200m will subtend an angular separation of 9.1′ and 8.6′, respectively in an 8x glass. The difference is about 0.5′, which is just on the cusp of discernibility under ideal conditions. The same result at 10x gives 0.6′; only a trifle better. So we may conclude that this 3D phenomenon all but vanishes in the Nikon E II 8 x 30 beyond about 200m distance.

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Optical Assessment: 

I began my optical tests by shining a bright white light source through the binocular and examining the visual image produced. The result was excellent; there were no annoying internal reflections, diffraction spikes or diffused light around the light source, showing that the anti-reflection coatings were performing well and that the glass was very homogeneous. This was confirmed after dark by looking at a bright yellow sodium street lamp. The image was clean and nicely contrasted with no internal reflections. Indeed, porro prism models do not produce diffraction spikes unlike some premium roof prism models.

Next I examined the exit pupils of both barrels of the Nikon E II. Below are images taken of the left and right pupils.

Left exit pupil.

Right exit pupil.

The pupils look nice and round, with little in the way of extraneous stray light encroaching on them. The reader can make out some weak reflections from the prisms quite a bit away from the pupils and so will have minimal effect on the views.

The images served up by the Nikon EII are outstanding! But to elaborate; the enormous 8.8 degree field of view produces a stunningly beautiful and uniquely immersive image. Sharpness is superb almost to the edge of the field and then, only mild field curvature and a bit of pincushion distortion creeps in to slightly distort the image. The field is so large that it makes the Nikon Monarch HG 8 x 30 field seem small in comparison lol. Colour correction is excellent: I detected none on axis and only the merest trace of lateral colour observed under the most pressing of observing conditions, such as viewing layers of tree branches against a bright overcast sky. By the way, it achieves these stunning optics entirely without low dispersion(ED) glass, just like the highly lauded Swarovski Habicht porros.

Colour rendition is very natural and true to life. Glare is also very well suppressed in this instrument, including annoying veiling glare that sometimes shows up in other binoculars when viewing in the open air when bright sunlight is streaming down on your target. Brightness is also very satisfactory, even while viewing objects in the late evening. As the guys from allbinos measured back in 2015, it achieves a light transmission of the order of at least 90 per cent, but its very neutral colour cast indicates that the transmission graph is bound to be quite flat over much of the visual spectral range(410-700nm).

I measured close focus on my unit to be just 1.97m, well below the advertised 3m and fully in keeping with the majority of roof prism models. This came as a genuine surprise to me, as porro prism binoculars are not known for their good close focus. Of course, to get the most out of those close up views, I found it necessary to reduce the IPD of the instrument to mimic the natural ‘crossing of the eyes’ that happens as an object is placed very close to the body.

As discussed above, the 3D images served up by this porro prism binocular will knock your socks off! I enjoyed countless minutes over the last month glassing open fields, watching Jacob’s sheep and their beautiful new-born lambs enjoying the warm spring sunshine, and admiring the finest details on their black, brown and white fleece. The instrument also has excellent focus depth so only slight refocussing is required to see everything super clear from about 30m all the way out to infinity. Your eyes become acutely aware of the topology of the landscape, as you view over hillocks and small depressions in the field. Mole hills transform into architectural wonders.

One of the great virtues of instruments such as this, is the significantly reduced amount of time you spend focussing and the increased time spent just observing! In a forest say, you focus once and, more or less, forget it! These special properties also make it the ideal binocular for viewing landscapes. I have been bowled over by the sheer amount of information each image relays to my eyes and the super large field helps reel in many unexpected visual trinkets. For example, one afternoon, I was admiring the gorgeous lime-green tint of the young leaves on a large horse chestnut tree some 50 yards away, only to watch in sheer amazement as a group of noisy Oystercatchers were captured flying across the valley in the deep background, some 300 yards distant. I could easily make out their long, ruddy beaks and black and white plumage as they raced through the air at breakneck speed. I have even learned to spot airborne Starlings and even the odd Jay in the same way, and over very long distances.  It’s the combination of excellent, glare-free optics, great focus depth, palpable 3D impression and class-beating field size, that creates the most powerful Majesty Factor I have personally experienced in any binocular, period.

Panning the edges of large swathes of forest is supremely comfortable with the Nikon E II 8 x 30. I have yet to experience any blackouts or the stomach-churning rolling ball effect I often experienced while observing with the Nikon Monarch HG 8 x 30. It’s also very well collimated.

Any niggles at all? Not really! OK, It’s not waterproof, and I would have liked to see some rubber armouring covering the chassis, but I guess that might put some folk off( yes, some folk care more about how a binocular looks than what it delivers optically, I kid you not!). I’ve recently acquired an excellent Opticron SR.GA 8 x 32 porro that does have this armouring, which will help protect it against the elements that little bit better. It too delivers very fine images, just a notch below those served up by the Nikon. But in all honesty, simple common sense is all that’s required to keep it safe from the worst of the weather and more careful attention to long-term storage of the binocular will help keep it in tip-top shape.

I plan to use the Opticron SR.GA for routine work, especially over the winter months and employ the Nikon E II only when conditions demand the very finest optics. That way, both will enjoy a long lease of life.

One in a million!

The Nikon E II is becoming more difficult to source. I note that several Nikon sites no longer advertise it. I received mine from Dutch stock, so I know they can still be found at reasonable prices. For sure, I’m very late to the party, but if you want to experience that superlative optical performance in a neo-classical compact porro design, now would be a good time to acquire one…………..before they’re all gone!

 

 

Happy Hunting & Thanks for Reading!

 

 

 

De Fideli.

A Closer Look at Two Compact Porro Classics.

The Carl Zeiss Jenoptem 8 x 30W(left) and the Opticron Dioptron 8 x 32(right).

A Work Commenced April 24 2022

 

I don’t suppose you’ve noticed, but I’ve taken rather a shine to a number of compact porro prism binoculars of late, having spent the vast majority of my time exploring roof prism models. After having test driven a few models now, I’m rather taken by their considerable charms, not least of which is their simple design, excellent optics, and much smaller price tags than similar quality roofs. Before I pulled the trigger on a few top rated models, I took some time to get a feel for a couple of classic models in the 8x 30/32mm aperture class. Accordingly, I bought up two models on the second-hand market for field testing; the Carl Zeiss Jenoptem 8 x 30 and the Opticron Dioptron 8 x 32, as shown above. In this short blog, I’d like to relate some details about these two models and how they perform after all these years.

I purchased both models from ebay. There were many Zeiss DDR Jenoptem models available for sale in all sorts of condition. That helps stabilise their market price to between about £60 and £100 UK. I settled on a late-1980s model(serial # 6722320), with the famous T3M multi-coatings, which, for their day, were well ahead of anything else on the market.  The unit I purchased was in excellent working condition, without any visible damage to the optics, and devoid of internal fungus infestations. The binocular came in its original brown leather case, which needs a few stitches to restore it to full working order, as well as a nice leather lanyard.

The c.1988 Carl Zeiss Jena Jenoptem 8x 30 ocular lenses with famous T3M multi-coating.

The objectives looked pristine after I gave them a thorough clean:

The well preserved anti-reflection coatings on the 30mm objectives. Note the serial number indicative of the era in which it was manufactured.

Some background research informed me that the leather case originally supplied with the instrument was lined in a fetching rose-coloured lining:

The original case, with its nice rose coloured lining.

The instrument arrived well collimated. The central focus wheel operated smoothly, with no free play or backlash. I was very impressed when I took my first look through it. The image was bright and very sharp within its very generous sweet spot. I was especially taken aback by the enormous field of view; fully 8.4 angular degrees! The dioptre compensation ring, located under the right ocular, moved smoothly but was easily nudged out of place.

Observing in an open field, in bright, spring daylight, showed that glare was quite well controlled but certainly more than I’ve seen in most modern instruments. Still, the sheer majesty factor of the field of view made a very deep impression on me. I was especially taken by the wonderful 3D pop to the images, which I found very engaging. As this instrument was more than 30 years old, I was expecting some internal reflections when I turned the instrument on a bright light source; and rest assured, a few did show up.

The instrument presented a very warm image but it was not as yellow as other reports have suggested. Maybe this was because I had a quite late model of this world famous binocular – I’m not entirely sure- but I was surprised to learn that its maximum light transmission peaked at about 91 per cent in the optimal, green-yellow visual range, according to spectrophotometric measurements conducted by Allbinos on a slightly earlier, 1985 model.

Short on eye relief though, but amazing if you manage to hook your eyes up with those ocular field lenses!

All in all, a very nicely operating classic compact porro, and quite collectible even in the 21st century. It certainly puts a smile on my face every time I use it.

The next model is a later dated instrument from the UK-founded Opticron optics firm. Called the Dioptron 8 x 32, it was fashioned in Japan and dates to the mid-1990s. Thus, it represents the next step in the intelligent design of the compact porro prism binocular. I picked this model up for just £50 plus shipping.

The Japanese-made(c.1995) Opticron Dioptron 8 x 32, together with its bonded leather carry case.

Though of slightly lower profile than the Zeiss Jenoptem, the Dioptron weighs roughly the same as its German counterpart, so its one chunky little glass.

Note the nice multi-coatings on the ocular lenses.

The Japanese origin of the Dioptron is betrayed by the stamp on the front of the binocular, which unscrews to allow it to be mated to a tripod:

Made in Japan.

The instrument also arrived well collimated, which flies in the face of those who insist that porro prism designs are much more susceptible to misalignment than their roof prism counterparts. If you mistreat any binocular, you’re in for trouble. But treat them well and they will serve you for a lifetime.

The objectives show a very prominent blue anti-reflection coating, unlike the prominent purple hue on the Jenoptem objectives.

The anti-reflection coatings on the mid 1990s Opticron Dioptron 8 x 32.

The big difference between the models is the focus wheel. In a departure to classic German compact binoculars, the Dioptron focus wheel is much larger and easier to access than that of the Jenoptem. Even after all these years, it works like a dream. Very high quality indeed!

Note the much larger and easier to access focus wheel on the Opticron Dioptron.

One slightly niggly thing about both instruments is the easily moved nature of the dioptre rings. Taking them in and out of their cases generally bumps the dioptre off its optimal setting, and even when holding them up to your eyes is quite enough contact to make them wander. Thankfully, this problem is all but fixed in later models.

Overall, the Dioptron is extremely easy to use, even though it shares the same poor eye relief with the Zeiss Jenoptem. Optically, it offers up a very good image, slightly better in fact than its German counterpart, but what genuinely surprised me was the strong colour cast of the images it serves up. It was considerably yellower than the older Zeiss glass. I would describe it as very ‘warm.’ And going from 8.4 angular degrees in the Zeiss down to 8.25 degrees in the Dioptron is quite noticeable to my eye. The Opticron does have noticeably better control of glare however, which renders its images that little bit more contrasted than the Jenoptem.

Both the Carl Zeiss Jenoptem and the Opticron Dioptron classics can be enjoyed entirely on their own terms. I’ve taken both instruments out on long walks in the countryside and have thoroughly enjoyed the lovely large fields of view and very large sweet spots, as well as the characteristic 3D pop they both command. The worst of the glare is seen when these instruments are pointed near bright light sources, but a lot of this can be removed simply by shading the objectives with your hands.

Both instruments helped me to finally make the transition to using high quality porros in preference to roof prism models when using compact binoculars in the field. The transition feels entirely natural for me.

After all, I’m a dyed-in-the-wool classicist don’t you know!

Thanks for reading!

 

De Fideli.

Product Review: Opticron Imagic TGA WP 8 x 32.

A Work Commenced April 13 2022

 

 

Product: Opticron Imagic TGA WP 8 x 32

Country of Manufacture: China

Chassis: Rubber armoured Aluminium Alloy & Polycarbonate chassis

Exit Pupil: 4mm

Field of View: 122m@1000m(7.0 angular degrees)

Dioptre Compensation Range: 7.5(with click stops)

Close Focus: 2.5m advertised, 2.26m measured

Eye Relief: 21mm

Prism: BAK4

Coatings: Differential Broadband Multi-coated, Proprietary F-Coat

ED Glass: No

Tripod Mountable: Yes

Waterproof: Yes

Nitrogen Purged: Yes

Weight: 614g advertised, 615g measured

Accessories: Lanyard, soft  leather carry case, microfibre cloth, ocular and objective covers, instruction manual and warranty card

Warranty: 30 years

RRP: £149

Several weeks ago, I began an in-depth investigation of porro prism binocular designs, having exhaustively examined many dozens of the more popular roof prism models, now saturating the market. My testing of two models from the internationally established optics manufacturer, Opticron, in particular, whetted my appetite for more studies on this highly traditional binocular design, so much so that I soon became enamoured by their charms.

In this blog, I will be reporting my findings on yet another Optricron-made porro prism binocular, the Imagic TGA WP 8 x 32, which has once again astonished this author in regard to the quality of both the optics and the design of the chassis, and which has caused him to radically re-think which models he wishes to use in the future.

Though I’ve been investigating the binocular market for just a few years now, I’ve had more of my fair share of fun with a number of Opticron-branded binoculars. Opticron began trading back in 1970 here in the UK, founded by a family passionate about bringing good value instruments to a rapidly expanding sports optics market. Today, Opticron enjoys a substantial part of the global market for binoculars, spotting scopes and a host of other optical technologies, and has gained the trust of many thousands of enthusiasts on every continent on God’s earth. Like the majority of companies in this industry, production of Opticron products has moved mostly to the Far East, either in China or Japan, where their well-orchestrated productions continue to manufacture high quality optical products to sate the demands of customers from every economic bracket. Today, their optical wares are well respected as offering exceptional value for money, and backed up by some of the best warranties in the industry.

Sourcing the Binocular

The Opticron Imagic TGA range of porro prism binoculars originally consisted of a 8 x 32, 8 x 42, 7 x and 10 x 50 models. The larger aperture models have earned a good reputation with stargazers, and are still going from strength to strength, but in the summer of 2020, the two more compact models  – the 32mm and 42mm – were discontinued. I was lucky enough to source a 8 x 32 model from The Birders Store, Worcester, which was being offered at the excellent sale price of just £109; a roughly 33 per cent knock-down on its recommended retail price. At that price ’twas a no brainer!

The binocular arrived very well packed. To be honest, I was quite taken aback by the very substantial build of the instrument and the rather fetching soft leather case it was supplied in. Tipping the scales at 615g, this is quite a hefty 8 x 32, about 65g heavier than an average 8 x 32 but not quite as hefty as the Leica Trinovid HD 8 x 32(650g) I once had the pleasure of owning. I elected to remove the blue and silver waterproof sticker from the front of the rubber armoured chassis pretty much immediately. Here it is in all its glory:

The Opticron Imagic TGA WP 8 x 32, with its ocular and objective lens covers attached.

Ergonomics

The instrument is built like a proverbial tank. The bridge is made from high quality, machined aluminium, while the optics appeared to be accommodated in a polycarbonate housing, overlaid by a thick rubber armouring. Picking the instrument up and holding it in my hands, I immediately felt very comfortable with it.

Small porros are so nice to handle!

Like the lighter weight Savanna model I recently showcased, the binocular is exceptionally stable in my medium sized hands. These compact porro-prism designs are so very easy to grip, with plenty of contouring on the body to prevent accidental slippage while glassing.

The eyecups are thoroughly modernised, just like the Savanna 8 x 30 I  reviewed. They offer a very comfortable 21mm of eye relief and twist up before locking rigidly into position. Those who wear eye glasses will be delighted to hear that the entire field of view can be very comfortably observed. The cups themselves appear to be fashioned from metal and covered by soft rubber. I find them to be very comfortable to place my eyes against.

The Opticron Imagic TGA WP 8 x 32 has very well designed eyecups that offer a very generous 21 mm of eye relief, making observing with eye glasses exceptionally comfortable.

The focus wheel is very large and easy to access. Turning through just 0.75 revolutions from nearest focus to just beyond infinity, I would describe its kinematics as very fast. That said, the motions are very smooth, backlash free and it enjoys a nice amount of tension, moving easily with a finger’s worth of torque.

The dioptre compensation ring is remarkable, especially considering the modest price I secured the instrument for. It is very sensibly located under the right ocular, and has a very ingenious click-stop design. One adjusts it in the normal way, by rotating it either clockwise or anti-clockwise, but it locks rigidly into place once your desired setting has been achieved. If you look carefully under the dioptre ring, one can make out numerous  tiny teeth that enable the ring to slot into and hold its position well. This clever piece of engineering ensures that it will not move out of position, unlike some of the vintage designs I’ve had the pleasure of using while furthering my education in porro prism binocular use. Those other models have a dioptre ring that moves far too easily, making it almost essential to re-adjust the setting each time the instrument is taken out of its case.

The exceptionally clever and beautifully designed click stop dioptre compensation ring. Note the numerous tiny teeth under the rotating ring. Each slot between two consecutive teeth represents a ‘click stop.’

The optics are fully multi-coated and have been bestowed with a proprietary ‘F coat,’ which apparently enhances colour contrast. The colour casts under daylight conditions show that they are significantly different to the greenish casts observed on the Savanna 8 x 30 objectives. Looking straight through the objectives, the lens almost ‘disappears,’ indicating that the coatings were doing their job well. The objectives are recessed reasonably well too; not as deep as others I’ve used, but certainly not the worst I’ve seen by a long shot.

The distinctive anti-reflection coatings applied to the Opticron Imagic TGA WP 8 x 32.

The ocular lenses are also thoroughly modernised, presenting with large, 21mm diameter field lenses, so rendering eye placement child’s play. Intriguingly, the colour cast of the anti-reflection coatings on the ocular lenses is distinctly different to that presented on the objectives. I wonder if this is an example of a so-called differential multi-coating?

Check out the large (21mm) ocular field lenses.

All in all, the Opticron Imagic TGA WP 8 x 32 is a very robust and well designed binocular that is a pure joy to hold and view through. I can see why the company was offering this instrument with a 30-year warranty. It’s clearly built to last!

Optical Assessment

The instrument arrived perfectly collimated; and I mean perfectly! Indeed, I’ve not encountered a better collimated instrument than this compact porro from Opticron. Directing an intensely bright beam of light though the instrument showed no annoying internal reflections, diffraction spikes or diffused light around the light source. In addition, the binocular showed no glare or internal reflections when aimed at the April full Moon This was a very satisfactory result, as you can enjoy this binocular looking at illuminated objects at night, such as a city scape or harbour if star gazing is not your forte.

Examining the entrance pupil of both oculars showed nice round results. Nor was there much in the way of stray light near the exit pupils as you can see below:

Left eye.

Right eye.

Optically, the view through the Opticron Imagic TGA WP 8 x 32 is very impressive! The image is very sharp, contrast rich, and glare free. The sweet spot is very large – approximately 80 per cent – with only mild field curvature and some pincushion distortion creeping in as the field stops are approached. Indeed, it is this pincushion distortion at the field edges that helps keep the rolling ball effect at bay. Glassing the edges of wooded areas along a quarter mile stretch, produced none of the nauseating effects I encountered with models employing field flatteners. Chromatic aberration was pretty much absent from the centre of the image. but some lateral colour could be seen at the edge of tree branches observed against a bright, overcast sky. I took an image through the Opticron Imagic TGA 8 x 32 with my IPhone 7 to give readers an idea of how nicely corrected the field of view is:

The nicely corrected field of the Opticron Imagic TGA WP 8 x 32. 10-burst images with a 3-second delay through an IPhone 7. The image is totally unprocessed.

The central sharpness of these modern porros is quite remarkable. Glassing side by side with a highly-rated GPO Passion ED 10 x 32 ED roof prism binocular showed similar levels of sharpness for each instrument. The colour tone in the Opticron Imagic TGA 8 x 32 is more neutral than the GPO ED glass though, which showed somewhat warmer colours. If I’m being honest, I felt the Opticron delivered a colour rendition more true to life than the GPO.

Control of glare is very good indeed. Turning the binocular to a bush immediately below the Sun in a late afternoon sky, showed only minimal flaring, which could be largely eliminated by shading the objectives with an outstretched hand. Control of veiling glare was also impressive in this little Opticron porro; very comparable to the GPO Passion ED 10 x 32  I tested it against.

If you’re used to the enormous(8 degree +) fields of view of other small, classic porros, you may find the 7 degree true field of the Opticron Imagic TGA  to be a little restrictive. Indeed, in comparing the view in this binocular to the Japanese-made Opticron Dioptron 8 x 32 with its 8.25 degree field, gave the distinct impression that depth perception in the latter was a little bit more pronounced than in the modern Imagic. Indeed, I’m of the opinion that the 3D-like images served up by porro prism binoculars scales inversely with magnification and directly with field of view. For this reason, perhaps the most pronounced 3D images will be rendered with a 6 x 30 porro prism binocular. Where the modern Opticron excels though is image brightness. Comparing the images in a late model Carl Zeiss Jenoptem(1988) 8 x 30W and the Dioptron 8 x 32(late 1990s) showed that the Imagic was producing a brighter image than either, and with better contrast to boot. Clearly, the superior effects of these modern anti-reflection coatings were in evidence.

 

Concluding Comments & Recommendations

A binocular worth a 30-year warranty.

The Opticron Imagic TGA WP 8 x 32 is an excellent binocular, offered at an excellent retail price. I suspect that it had simply fallen below the radar of many binocular enthusiasts on account of its simple porro design and the steep competition it no doubt faced in light of all the roof prism models that were hitting the market at the same time. But having thoroughly tested this instrument, I cannot help but recommend it to anyone interested in acquiring an optically sound and mechanically excellent product, at a price that won’t break the bank. It’s a great shame it has been discontinued, but I have it on good authority that Opticron will still honour the 30-year warranty offered with the instrument, so the owner can be assured that they will take care of it should you hit any snags. I’m also very impressed with the accessories that came with the instrument, particularly the rather fetching soft leather carry case to store it in.

Even the carry case exudes quality.

More generally, I’ve enjoyed using these wonderful, cost-effective porro prism binoculars so much that I’ve become a firm fan. I feel their excellent 3D images add a new dimension to the observing experience, and their excellent value for money appeals to my desire to acquire the very best bang for buck I can get with my disposable income. The reader will note that the very best compact porro prism designs can still be had for prices roughly a quarter of those garnered by the best roof prism models. What’s more, the considerable advantages porro prism designs enjoy greatly outweigh their perceived disadvantages, in my opinion. And that’s great news for all binocular enthusiasts!

 

Thanks for reading!

 

 

Product Review: The Opticron Savanna 8 x 30.

The Opticron Savanna 8 x 30 package.

 

A Work Commenced April 2 2022

 

Preamble 1

Preamble 2

Preamble 3

Preamble 4

 

Product: Opticron Savanna 8 x 30

Country of Manufacture: China

Exit Pupil: 3.75mm

Eye Relief: 18mm

Close Focus: 3m advertised, 2.8m measured

Field of View: 131m@1000m(7.5 angular degrees)

Coatings: Fully Broadband Multi-Coated

Chassis Contruction: Rubber armoured aluminium alloy and polycarbonate

Prism Types: Porro BAK4

ED Glass: No

Tripod Mountable: No

Dioptre Compensation: +/- 3

Waterproof: Yes

Nitrogen Purged: Yes

Weight: 491g advertised, 458g measured

Dimensions: LxWxD (cm)/ 11.6×16.0x4.0

Warranty: 10 Years
Accessories: logoed neoprene case with rain guard, logoed neoprene strap and objective lens caps, lens cleaning cloth, instruction & warranty card
Price(UK): £105.49

 

Porro prism binoculars have received quite a bit of bad press in recent years. In surveying some of the literature, I’ve read that they’re heavy and unwieldy, lack water-and fog-proofing, and are more prone to misalignment of the optical elements than their roof prism counterparts. Others seem to have dismissed them purely on aesthetic grounds, citing their ‘ugliness’ as a reason to reject them. How shallow is that? But after extensively testing a thoroughly modern porro prism binocular from Opticron – the Savanna 8 x 30 – I’ve discovered that many of these assumptions are either misleading or totally untrue.

Let’s begin by listing some of the key advantages of porro prism binoculars.

  1. They are much more economical to manufacture to a high standard than roofs.
  2. They have much more forgiving design tolerances than roof prism binoculars.
  3. They offer naturally brighter images, owing to fewer reflections through porro prisms
  4. They offer very wide fields of view with simpler eyepiece designs
  5. They throw up much more pronounced 3D or stereoscopic images than their roof prism counterparts

Having said all that, this new model offered by Opticron promises to dispel many of the traditional reasons why porro prism binoculars have fallen out of favour with birders, hunters and outdoor enthusiasts. To see why, read on.

Ergonomic Features

The first thing that grabbed my attention was the feather light weight of the Opticron Savanna 8 x 30. Tipping the scales at just 458g(without the strap), this is actually one of the lighter models on the market. For example, the Nikon Monarch HG 8 x 30 comes in at only 8g less!

The Opticron Savanna 8 x 30 is well armoured for outdoor use and is very light weight.

The chassis is covered in a nicely textured rubber armouring that feels quite spongy to the touch, protecting the instrument from accidental knocks and bumps.

The central hinge is nice and rigid, keeping my optimal IPD even after taking it out of its tightly fitting soft carry case many times during my tests.

Underside of the Savanna 8 x 30.

The eyecups are strong and are of good quality, and twist up like most roof prism models. This is a departure from the fold-down rubber eyecups I’ve seen on a few other porro prism designs. They click rigidly into place, but there is no provision to set them at an intermediary position. I rather like two stage eyecups like this, as I’ve not found an intermediate detent in any binocular that conveys a more comfortable view. The eye relief is quite generous though. I was able to image the entire field comfortably using eye glasses.

The twist up eyecups lock rigidly into place and are very comfortable to place one’s eyes against.

The focuser is very large and easily accessed. Movement is smooth and firm with very little in the way of play. What’s more, the focuser only rotates through about three quarters of a full revolution in order to go from one end of its focus travel to the other. Close focus was measured to be 2.8m, significantly closer than the advertised 3m. It also focuses a wee bit beyond infinity, useful for snapping edge of field objects into tighter focus.

The ocular field lenses are large( 21mm in diameter), making eye placement easier to achieve and comfortable to place one’s eyes against.

 

The ocular field lenses are large for easy eye placement.

The dioptre compensation ring is located under the right ocular lens. It moves with a nice amount of rigidity.

The external focuser is fashioned from aluminium which affords good tensile strength. Examining the progress of its motions, I was delighted to see there was zero wobble as it was racked in and out of focus. The binocular is advertised as waterproof and fog proof( nitrogen purged), so I assume it’s o ring sealed. This may come as a surprise to roof prism fans, but surveying the market, there are several other porro models that claim the same.

One very welcome feature is the minimum inter-pupillary distance of 50mm, making it eminently suitable for those of us who have smaller faces. These will work brilliantly with kids!

The small 30mm objective lenses are very deeply recessed. This is a very welcome feature, as it protects the objective lenses from rain, dust and stray light. My experiences over the last several years has taught me that models without very deeply recessed objectives display higher levels of glare during field use

In the hands, the Opticron Savanna 8 x 30 feels great. There are plenty of places on its nicely contoured body to wrap your fingers round. Indeed, I’ve not held a more comfortable binocular in quite some time! Overall, this appears to be a very nicely designed porro prism binocular, incorporating many of the great features found in roofs costing substantially more!

Now, let’s talk about optics.

Optical Assessment

The binocular arrived in good collimation, as judged in daylight testing and by examining the bright star Arcturus, defocusing it using the right eye dioptre. By directing a beam of intensely bright light into the binocular objectives, I was able to verify that there was no annoying internal reflections, diffraction spikes and only a very small amount of diffused light around the light source. The result was just as good, in fact, as a top-rated roof prism control binocular I used as a control – the GPO Passion ED 10 x 32. I measured the effective aperture as effectively 30mm by directing a beam of light through the ocular lens and measuring the diameter of the emerging disc of light. There was also no internal reflections when I tuned the binocular on a bright sodium street light after dark.

The Opticron Savanna 8 x 30 throws up a very impressive image. The sweet spot covers about 80 per cent of the field, with mild field curvature setting in as the target was moved to the edge of the field. Contrast is excellent too. Comparing it to the less expensive Adventurer T WP 8 x 32 porro prism binocular, the Savanna displayed far less glare. Veiling glare was also far less pronounced in the Savanna too but not quite as well controlled as in the GPO 10 x 32 binocular costing three times its modest price tag. Though the field of view is smaller than in the Adventurer T WP 8 x 32(8.1 degrees), it’s much cleaner, with nicer edges and a clearly defined field stop.

The Opticron Savanna 8x 30(left) is a good step up in performance from the less expensive Adventurer T WP 8x 32( right).

The Savanna 8 x 30 image is very bright and tack sharp within its generously large sweet spot. In careful side-by-side tests with my GPO 10 x 32 Passion ED, I judged the images as equally sharp(or maybe a tad sharper in the Savanna porro) in the middle of the field, but fell short of the roof prism bino from about 50 per cent of the way from the centre to the field stops. In addition, the colour tone of the Savanna 8 x 30 was very neutral in comparison to the warmer colours garnered with the GPO. Chromatic aberration was not seen on axis, and only a trace was detected off axis while looking at denuded branches of trees against a bright, overcast sky. This shows, once again, that a good binocular needn’t employ ED glass to deliver a really good image. Indeed, all of the top porro models now available don’t employ ED glass.

Go figure!

The Opticron Savanna 8 x 30 ( right) compares quite well with a high quality roof prism binocular(left).

In yet another test, I ordered up a classic Opticron Dioptron 8 x 32, a vintage Japanese- made instrument dating to the late 1990s. I was amazed to discover how much brighter the Chinese-made Savanna 8 x 30 was in comparison. Sporting a field of view of 8.25 angular degrees, the Dioptron also enjoys a large sweet spot but once outside it, the images of stars rapidly deteriorated as they were moved towards the field stops. In comparison, the 7.5 degree field of the Savanna 8 x 30 kept those same stars under much better control even near the edge of the field. Though the Dioptron is also fully multi-coated, it showed some prominent internal reflections, unlike the Savanna, and daylight images were noticeably yellowed(warm) in comparison to the much more natural colour tones served up by the modern Savanna binocular. Glare was also much better controlled in the Savanna in comparison to the classic Dioptron  8 x 32. Indeed, I judged the less expensive Adventurer T WP 8 x 32 to have similar levels of glare to the Dioptron. What was also surprising to me however, was the finding that the Adventurer T WP delivered a brighter image than the Dioptron in daylight tests.

The Opticron Savanna 8 x 30 delivered a much brighter and more contrasted image than the classic Japanese made Opticron Dioptron 8 x 32(left).

Collectively, these tests convinced me that great advances in coating technology have occurred in the last two decades, with even low cost ‘econo’ binos serving up noticeably brighter and more contrasted images than some of the best porro prism binoculars available from the late 20th century.

The Remarkable Phenomenon of Stereopsis

One of the things that struck me as being very obvious and visually striking in the Opticron Savanna 8 x 30, was its ability to generate wonderful depth perception, or stereopsis, as it’s referred to in the technical literature. Focus the binocular in the middle distance and objects remain razor sharp all the way to infinity. What does that translate to in field use? Less frequent focusing. Looking at some conifer tree trunks lying beyond my back garden, and comparing the view in a few roof prism models, revealed the total superiority of the Savanna porro in conveying three-dimensional, spatial information or contouring of the tree trunks in relation to each other. Simply put; more details remain in sharp focus compared to a good roof prism binocular imaging the same field. In another test, I used a very nice 8 x 42 ED roof prism binocular to focus in on a chimney some 40 yards in the distance, but background trees at about 65 yards distant were a little blurred, lacking information:- a wee bit out of focus. Not so with the little 8 x 30 porro prism binocular from Opticron! Both targets remained sharp! The effect becomes less pronounced at distance though. But for walks in the woods, where trees litter the landscape both near and far away, I can’t think of a better instrument than a small high-quality porro like this to enjoy those views!

Compared to good roof prism binos, like this Barr & Stroud Series 5 8x 42 ED, the Opticron Savanna adds much more depth perception to the images.

Indeed, I’ve now come to see this effect as adding valuable information to the binocular image – just as our eyes were created to do.

Let’s just say roofs lack dimensionality in side by side comparisons.

 

Conclusions & Recommendations

Ain’t she purdy?

The old adage is certainly true; you have to go to great lengths to make a roof prism binocular as good as porro prism designs. The quirky little Savanna 8 x 30 takes a tried and trusted optical design and puts a thoroughly modern accent on it. For the modest price of just over £100, you get an instrument that has excellent optics and ergonomics. It totally smashes the stereotype of porro prism binoculars being big and clunky. And it’s quite a good looking binocular too, don’t you think?

My experiences with this lovely little instrument has consolidated my conviction that porro prism binoculars will be my instruments of choice in the compact-size format, with their unparalleled 3D-enhanced images and brilliant, sharp, high contrast optics. I would highly recommend this instrument to savvy binocular enthusiasts wanting to get the absolute maximum bang for buck. I would also recommend the instrument or its lower power sibling – the Savanna 6 x 30 –  for younger individuals or adults with smaller faces. Rest assured, it will embarrass roof prism designs costing a few hundred pounds and the solid 10-year warranty from Opticron will put your mind at ease that it will stand the test of time.

Thanks for reading!

 

Dr Neil English is the author of a highly lauded 650+ page history of visual telescopic observing; Chronicling the Golden Age of Astronomy.

 

.

 

 

De Fideli.

Product Review: Opticron Adventurer T 8 x 32.

 

The Opticron Adventurer T WP 8 x 32 package.

A Work Commenced March 20 2022.

 

 

Product: Opticron Adventurer 8 x 32 T WP

Country of Manufacture: China

Chassis Material: Rubberised Aluminium & Polycarbonate 

Exit Pupil: 4mm

Field of View: 142m@1000m(8.1 angular degrees)

Coatings: Fully Multicoated on all glass surfaces

Prisms: Porro BAK4

ED Glass: No

Close Focus: 3m advertised, 3.24m measured

Dioptre Compensation: +/- 5

Waterproof: Yes

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: 540g measured

Warranty: 2 Years

Dimensions LxWxD (cm): 10.9 x 16.9 x 5.0

Price(UK): £61.00

 

Introduction

Every now and then, a product finds its way to me, challenging what I know and understand about binoculars, and their market. As you may have gathered, I have spent the vast majority of my reviews on modern roof prism designs, which are understandably very popular with nature enthusiasts, birders and hunters alike. The advantages of roof prism models include their compact, sleek design, internal focusing and ease with which they can be rendered weather resistant. But for all their charms, roof prisms are much more difficult to make well compared with the older, more traditional, porro-prism designs. For one thing, they need specialised phase corrections coatings that bring the electric field vectors into precise alignment after being shifted out of phase, travelling through the roof prism. They also require aluminised, silvered or dielectric coatings to boost the light transmission to the eye to achieve their high-contrast images, that can begin to compete with their porro-prism counterparts. But while the market has clearly moved in favour of roof prism designs, it’s good to see that some of the leading binocular manufacturing companies have retained one or more porro-prism models that offer wonderful optical performance in classic configurations. I speak of course of the Swarovski Habicht, for example, which is still available in 30mm and 42mm formats, and offer exceptional optical performance at prices substantially below their equivalent roof prism counterparts.

Zeiss also continued their manufacturing of classic porro-prism designs, like the multicoated Jenoptem 8 x 30, well into the 1990s, and the later models still provide excellent optical performance. Nikon also makes its highly-lauded EII as a premium product, as well as a number of less expensive porro-prism models – the Aculons & Actions come to mind- that deliver decent optical performance, apparently. But it’s also nice to see other binocular companies like Opticron, Vortex, Kowa, Olympus, Canon and Leupold continue to offer small porro-prism binoculars at very economical prices.

Truth be told, with vast improvements in optical glass quality, modern multi-coating technology, and advancements in materials science, it’s possible to produce an optically excellent porro-prism binocular for a very modest financial outlay. This review will describe the optical and mechanical features of a charming little porro-prism binocular by Opticron; the Adventurer  8 x 32 T WP.

Inspiration from Fellow Astronomy Authors

My attention to the Opticron Adventurer T WP 8 x 32 was piqued after reading some reviews made by British binocular astronomer, Stephen Tonkin, who showcased a very interesting Adventurer T WP 10 x 50 model, and highly recommended this model as a well-built and optically excellent stargazing binocular available for under £100. Indeed, this was also reflected in the many favourable reviews left by stargazers about the same model. But there was almost nothing mentioned about the smaller models from the same line; namely the 42mm and 32mm models. I discovered that 32mm Adventure T WP had a nice, light weight- 540g – quite typical even for a roof prism model of the same aperture class. It offered a good, wide field of view too – 143m at 1000m – again right up there with some of the widest fields available in the top-selling roof prism brands. But unlike many older models, which offered just coated or multi-coated optics, these porro-prism binos from Opticron were fully mutli-coated, ensuring a high light transmission – at least in theory.

I decided to order up the Opticron from Amazon, which was offering the instrument for a very attractive price of just £61. This was a little bit below what I would have expected it to sell for, so I suspected that I was going to get the binocular in an ‘open box’ condition, meaning that some previous customer opened up the package, briefly examined the instrument, before packing it away and sending it back to Amazon. Sure enough, when the package arrived, it certainly looked like the box was opened before!

Never mind!

Everything looked OK though. The binocular itself was very nicely built – much better, in fact, than I had expected, if I’m being honest. My initial impression was, ” this has got to be a Habicht clone,” so similar it appeared to the famous Swarovski classic.

Ergonomic Features

The Opticron Adventurer T 8 x 32 WP is a well built binocular, with solid mechanics

Holding it in my hands, I was very satisfied with its sturdy build. The central hinge is good and stiff, easily maintaining my preferred inter-pupillary-distance. The focus wheel is very nicely engineered, rotating smoothly with a fair amount of tension and without any play or backlash. The eye cups are the old-school rubber design but they felt quite comfortable to rest my eyes on. When folded down, the instrument can be used with eye glasses, but you’ll have to move your eyeball ’round to see it all, so a fairly tight squeeze! Dioptre compensation is achieved by rotating a ring located under the right ocular. It also moves smoothly but I would have liked to see that little bit more tension.

I hit my one and only snag as I began to remove the nicely designed objective covers from the barrels. The rubberised armouring immediately covering the left ocular came away, as I struggled to tease the objective cover off.

Bummer!

Fortunately though, I had some Gorilla glue handy, and simply applied a bit to the inside of the armouring before putting it back on. It worked a treat, but it did leave a few glue streaks around the rim, lol, as you can see in the photo below:

The underside of the binocular. Note the glued-on rubber armouring around the left objective. Minor issue, no sweat!

The objectives are quite deeply recessed, with the anti-reflection coatings almost disappearing in normal daylight. That’s a good design feature, as it affords greater protection from dust, rain and stray light.

The fully multi-coated objective lenses are nicely recessed for extra protection and do a great job preventing reflective glare coming off the surface.

I was delighted to see that Opticron made a provision for affixing the binocular to a tripod. Good move!

Though you may not use it, the Opticron can be affixed to a tripod if need be.

The binocular handles very well indeed. It’s super easy to grip and wrap one’s fingers ’round. The focus wheel is easily accessed and moves with a very reassuring amount of tension. Fit and feel are way better than I expected, given its rock-bottom price. But how did the optics hold up?

Optical Assessment

I had read that more economically priced porro-prism binos, like this 8 x 32, often have stopped down apertures. This was very easy to test however, simply by directing my Iphone torch through the ocular lens and observing the size of the circle of light projected through the objectives onto a flat surface. The results were very encouraging: the effective diameter was 31mm, quite in keeping with the 32mm advertised aperture.

Cool.

Next, I turned my phone torch to its highest setting and placed it about 4 metres away at the other end of my living room. Looking at the beam through the binocular produced yet another excellent result; there were no significant internal reflections or diffraction spikes. I did detect a small amount of diffused light around the beam, though I judged it largely un-injurious to the image. This I was able to confirm by imaging a sodium street lamp at night. There was no annoying internal reflections and just a small amount of diffused light immediately around the lamp. All in all, these results were thrilling, given the very low price I paid for this binocular!

In the next test, I photographed the entrance pupils on both the left and right ocular lenses. As you can see, the pupils were round, with no sign of truncation. Nor did they display the characteristic signs of cheaper BK7 prisms. I did detect some light leaks away from the entrance pupils however, but all in, not too shabby!

Left entrance pupil.

Right entrance pupil.

The Opticron Adventurer 8 x 32 T WP delivers a very good image in daylight tests. The sweet spot is generously large. Contrast and colour rendering were both excellent. Images snap to precise focus, with the focus wheel moving through about one and a half full rotations from nearest focus(measured at 3.24m) to infinity. What immediately impressed me most was the instrument’s extraordinary depth of focus, with objects in the middle distance and beyond taking on a wonderful, immersive three-dimensionality. This amazing effect is far more acutely perceived in this binocular than in any roof prism instrument I’ve had the privilege of using. Of course, porro-prism binoculars are known for this, but it still came as quite a surprise to me when scanning a stretch of river, an open field, or a woody glade. The viewing is extremely comfortable too. I encountered no blackouts or rolling ball effects while panning large swathes of wooded terrain.

Simple pleasures.

The binocular does suffer a little bit from glare, especially when it’s pointed near the Sun, but no more than many other binoculars I’ve tested costing many times more. In most situations, this glare can be minimised simply by outstretching one’s hand.

I noted very little chromatic effects within the sweet spot, but did begin to see traces as my eyes were directed towards the edges of the field. The periphery of the field becomes progressively more blurry, but the decline in image sharpness is very gentle and gradual. The main off-axis aberration is field curvature. I took the liberty of capturing an image of a nearby roof through the Opticron and compared it to the same image captured by a GPO 8 x 32 Passion ED costing more than six times more. I hope you’ll agree that compared with the GPO binocular, the little Opticron Adventurer T did very well indeed, both on and off axis.

 

10-burst raw image from the Opticron Adventurer 8 x 32 T WP with 3s delay.

10-burst image of the same roof as seen through the GPO Passion ED 8 x 32.

Though the captured IPhone images don’t fully convey the visual impressions garnered with the eye-brain interlocutor, they do show that the GPO delivers a punchier, more contrasted image. That said, the little Adventurer did very well indeed. The reader will also note the greater focus depth of the Adventurer T (see the tree in the background at the top of both images) as well as a little bit of vignetting at the edge of the field. Since the fields are broadly the same size, one can see field curvature is pretty similar in both instruments i.e. gentle.

While it was pretty clear from the get go that the Opticron Adventurer T was well collimated, as evidenced by the wonderful depth perception I experienced after merging the images, I did confirm this by testing on a bright star at night and it passed. Looking at a decidedly pinkish full Moon rising low in the eastern sky, the image was bright and sharp across the majority of the field. As the Moon was moved off axis toward the field stop, I did notice a significant brightness drop off at the edges, in keeping with the results seen in the image captured above.

Star fields were presented really well in the Opticron too, with stars remaining acceptably small and sharp across most of the field. Like many other binoculars I’ve showcased in the past, off axis aberrations are more pronounced panning the instrument vertically than horizontally. This will make a very decent stargazing bino for those who like to use smaller instruments.

Proof of Concept.

Conclusions

To say that I’m impressed with this little binocular would be quite an understatement. For the ridiculously low price I paid for it, the Opticron Adventurer 8 x 32 T WP performed WAY ABOVE expectations. It may be an inexpensive binocular, but boy does it perform! It’s lovely wide field, sharp optics and wonderful depth of focus will allure many. And while it’s no Habicht, it gets my highest recommendation as arguably one of the most charming instruments I’ve had the pleasure of reviewing.

Long live the classic porro prism binocular!

 

Thanks for reading!

 

De Fideli.

Product Review: GPO Passion ED 8 x 32.

 

The GPO Passion ED 8 x 32 package.

A Work Commenced March 5 2022

 

 

Preamble 

 

Product: GPO Passion ED 8 x 32

Country of Manufacture: China

Exit Pupil: 4mm

Eye Relief: 16mm

Dioptre Compensation: +/- 3

Chassis: Rubber armoured magnesium alloy

Field of View: 139m@1000m(8.0 angular degrees)

Close Focus: 2m advertised, 1.87m measured

Coatings: GPO Bright Fully Broadband Multicoated, dielectric and phase correction coatings.

ED Glass: Yes

Light Transmission: 90%

Waterproof: Yes

Nitrogen Purged: Yes

Tripod Mountable: Yes

Weight: 520g(advertised), 520g measured.

Dimensions: H/W: 11.8x 11.8cm

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

Warranty: 10 years 

Price: UK £327.99

 

In previous blogs, I reviewed two excellent binoculars from the new company, German Precision Optics(GPO). The GPO Passion HD 10 x 42  proved to be a phenomenal performer, easily as good as the best models built by Zeiss, Leica or Swarovski. Indeed, someone sent me word that the guy who started Optica Exotica waxed lyrical about the larger 12.5 x 50 Passion HD, comparing it favourably to the flagship Zeiss Victory SF models, both in terms of build quality and optical quality. Unfortunately you’ll have to pay for the privilege of seeing that review.

The more economically priced GPO Passion ED 10 x 32 matched my personal requirements much more closely though, delivering both excellent optics and ergonomics in a much more portable package. Recently, I bought up its 8x sibling for an in-depth review: the Passion ED 8 x 32, which is actually available in four colour schemes. Initially I just wanted the same black colour as my 10 x 32, as I’m not especially partial to two-tone colour schemes, but after seeing the green & black model under different lighting conditions, I settled for the latter, as the photo above shows.

First Impressions & Ergonomics

Like the previous GPO binoculars I showcased, the little 8 x 32 arrived in the same beautifully designed presentation box. All of the accessories were to be found inside the high quality hard clamshell case with its attractive GPO logo. The binocular itself was immaculately presented, with its attractive dark green and black rubber armouring covering the tough magnesium alloy chassis. The long, slender barrels have ample room to wrap my fingers round, delivering an ultra-stable viewing experience.

The GPO Passion ED 8x 32 is exceptionally pleasing to handle with its long, slender barrels to wrap your hands around. Note the Zeiss-like objective tether.

The same top-quality anti-reflection coatings present on the 10 x 32 are also present on the 8x model. They present a lovely magenta hue in broad daylight.

Ocular lenses.

Note the very deeply recessed objective lenses.

One very neat feature of the objective lenses is that they are very deeply recessed inside the top of the barrels. This affords exceptional protection from rain, dust and stray light.

The magnesium alloy central hinge is short but very strong. It has nice tension, easily keeping your preferred inter pupillary distance (IPD) while being stored or in field use.

The eyecups are fashioned from machined aluminium, overlaid with soft rubber, and have three positions. The cups lock rigidly into place, with no wobble or wiggle room. These are among the finest eye cups I’ve personally experienced from any binocular manufacturer, period. Eye relief is a tad better than on the 10 x 32 model too, and I was able to image the full field of view with the eyecups fully retracted using my eye glasses.

The eye relief on the GPO Passion ED 8 x 32 is generous and the entire FOV is visible using eye glasses.

The focuser is oversized and centrally located, taking just over one complete turn (~390 degrees) to go from one end of its focus travel to the other. Motions are very smooth and precise, with zero play when rotating it either clockwise or anti-clockwise. The level of tension is just right in my opinion, neither too fast or too slow, making it eminently suitable for birding, hunting or general nature studies.

The dioptre compensation ring is very sensibly located under the right ocular and is quite difficult to move. I noted the precise position it took for my right eye and was very impressed to see that it was adjusted to exactly the same position as on my 10 x 32. Neat!

The padded neoprene neck strap affords exceptional comfort when carrying the binocular around your neck. I choose to wear it high on my chest, to minimise the amount of swing the binocular undergoes while being carried.

Binoculars are especially joyful with a high quality padded neck strap.

The carry case and strap are of very high quality too. While there are similar cases offered by less expensive models, my experience with many of them is that the zipper breaks after a few months of use. Not so with this GPO clamshell case. I store the instrument with the eyecups fully extended, as shown below.

The GPO-logoed clamshell carry case affords excellent protection for your optical investment.

Optical Assessment

Having tested and enjoyed two other GPO binoculars, I was honestly expecting very good things from the 8 x 32 model. I began with my flashlight test, directing an intensely bright beam of white light into the binocular from across a room. I used the GPO Passion ED 10 x 32 as a control instrument in the same test. The result was very good. The beam showed no diffused light around the beam, indicating that the optical glass employed in the binocular was very homogenous. And just like the 10 x 32 ‘control’ binocular, there was no sign of annoying artefacts like diffraction spikes that can show up even in some high-end binoculars. I did detect a couple of very weak internal reflections in the 8 x 32 in comparison to the 10 x 32, but I deemed their presence largely non-injurious to the image. For example, when I turned the binocular on a bright sodium street lamp at night, those reflections were all but absent and neither were they apparent when I turned the binocular on a waxing crescent Moon. These results showed that the GPO Passion ED 8 x 32 can be used productively at night, for moon gazing and observing cityscapes from high-rise apartments, or monitoring harbour lights from an elevated vantage after dark.

In the next test, I examined the exit pupils as seen in front of an indoor lamp. The results(see below) were very encouraging: both entrance pupils showed no departments from circularity, and the area around each pupil was good and dark.

Left ocular.

Right ocular.

Right from the get go, I was taken by the quality of images served up by the GPO Passion ED 8 x 32, even during the dull overcast conditions on the afternoon the instrument arrived. The binocular serves up a very powerful optical wallop. Images snap to focus with no ambiguity across the vast majority of its impressively wide field. I would estimate the sweet spot to be about 85 per cent of the field of view, but falls off very gently as the field stops are approached. The remaining 15 per cent showed progressively more field curvature that younger eyes can accommodate to some degree(I have no trouble at 53), and some mild pincushion distortion near the field edges. Contrast is most excellent, with very good control of glare. Colours are vivid and true to form. Greens and browns are particularly well enhanced, especially as the late February-early March light faded in the evening. An overall light transmission of 90 per cent is very credible in my opinion.

I couldn’t detect chromatic aberration in the centre of the image. Viewing some denuded tree branches against a uniform, grey sky did throw up a trace of lateral colour from about 65 per cent of the way out from the centre, becoming a little more pronounced right at the edge of the field.

I took the liberty of capturing an image of a roof located some 35 metres in the distance with my IPhone 7 camera through the GPO Passion ED 8 x 32. It was taken with a 3 second delay and consists of a burst of ten images. No processing of any kind was done on the image. Although it certainly does not convey all the visual details, I think it does provide a fair indicator as to the quality of the field:

Unprocessed burst image of a roof located some 35 metres in the distance as seen through the GPO Passion ED 8 x 32.

 

Depth of focus on the GPO Passion ED 8 x 32 is quite remarkable, in my opinion. Looking across an open field on a bright sunny day, I was able to view objects from about 50 metres all the way to infinity in wonderful, sharp focus, as if you were there. Examining the trunk of an old, dead tree trunk some 25 metres away, generated vivid three dimensional details of the moss, fungi and wood grain, as though I could reach out my hand and touch it! I believe this very immersive depth perception was particularly vivid owing to the excellent sharpness across the majority of the image, coupled to its enormous field of view(8 angular degrees). Close focus was significantly better than advertised too. I measured it at 1.87 metres; good news if you like to observe insects, flowers, water courses and rocks at close hand.

Ad Astra

Testing binoculars under the starry heaven is arguably the best way to assess aberrations and to check alignment of the barrels. That’s because it’s easy to get overwhelmed by a daytime vista in all its rich detail, and it can be difficult to judge where off-axis aberrations begin to encroach. Stars and other celestial objects are much simpler animals in comparison, and how they distort as one moves off axis is easier to diagnose. The first thing I did was to check collimation. This was easily achieved by placing the brilliant star Sirius in the centre of the field, while the binocular is mounted on a tripod. The Dog Star is close to the meridian after dark on early March evenings, and so is very well placed for testing. The star is focused as finely as possible and then the dioptre ring is turned to the end of its travel to create a prominent anulus of light. If the binocular is properly collimated the perfectly focused left barrel will be located on or inside the defocused anulus. If not, you’ve got an alignment problem. Such testing confirmed that the GPO Passion ED 8 x 32 was very accurately collimated, with the focused star being located just off the centre of the anulus. Good job GPO!

Centring the magnificent and sprawling Hyades star cluster, now sinking fast into the western sky, showed that all of the constituent stars were morphologically well presented in the binocular. Moving the bright, ochre tinted Aldebaran from the centre of the field towards the edge revealed that it remained sharp and acceptably well focused across ~ 90 per cent of the distance to the field stop, bloating moderately in the last ten per cent of the linear distance to the field. Much of this bloating could be removed by slight refocusing, indicating that the main culprit was mild field curvature. This tests showed that the little 8 x 32 will make a  fine star gazing instrument, as I was to discover after my formal testing ended.

In another test, I observed how well the glorious crescent Moon retained its brightness as it was moved from the centre towards the field stop. I detected very little in the way of brightness drop off, indicating that near full-field illumination was retained all the way to the edges of the field. I detected no visible chromatic aberration on axis but did detect a trace of secondary spectrum as it was moved to about 60 per cent of the way to the field stop. And even at the field stops secondary spectrum was still fairly modest.

It is also worthwhile tweaking the dioptre adjustment under the stars. I often find that adjusting the dioptre on a daytime target does not offer the very best correction. Usually, I obtain rough adjustment on a distant signpost, but quite often I find that when I examine the images of bright stars in both barrels, the dioptre compensation can be a wee bit off and can be micro-tweaked on a star image.

 Differences between the 8 x 32 and the 10 x 32 Models

Apart from the obvious differences in the sizes of the field of view served up by the 8x and 10x GPO Passion 32mm binoculars, two other disparities are noteworthy. Firstly, the diameters of the field lenses on the eyepieces of the 8 x 32 are significantly larger than the 10 x 32. The 8x glass has a 21mm diameter field lens compared with just 18mm on the 10x glass.

The size on the field lens is significantly larger in the 8x 32 compared with the 10 x 32.

Intriguingly, I noticed that the larger ocular field lens in the GPO 8 x 32 ED induces some occasional blackouts(spherical aberration of the exit pupil) when first looking through the binocular, that are all but eliminated by paying more careful attention to obtaining the optimal IPD for my eyes. This is true irrespective of the fact that the 8 x 32 model has a larger exit pupil(4mm as opposed to 3.2mm on the 10 x 32). Despite its smaller field lens, I rarely, if ever, encounter blackouts with the 10 x 32. This result is also consistent with my previous blogs on the little Leica Ultravid BR 8 x 20(with its 2.5mm entrance pupil), where I reported little in the way of blackouts in field use, unlike some other reports I have read online. I believe this is attributed to the smaller ocular lenses on these binoculars, which forces one to centre one’s eyes more accurately from the start.

Secondly, there is a noticeable difference in the focus tension in the 10 x 32 compared with its 8x sibling. The latter has more tension than the former. I have found that this is actually a good thing going forward, as the 10x glass has a shallower depth of focus than the 8x, and so benefits somewhat from a faster focusing mechanism, especially  during glassing adventures in wooded areas.

Notes from the Field & Conclusions

Enjoying the great outdoors.

During most glassing excursions, only a quarter of a turn of the focus wheel is used.  A gentle touch is all that’s required to focus more closely or farther away. One of the great virtues of this 32mm format is its light weight, tipping the scales at only 520g. That’s light enough to be used all day long. This format is also ideal for the vast majority of birding activities, which take place under good lighting conditions. As expected, the larger exit pupil on the 8 x 32 serves up a brighter image than the 10 x 32, but only when the light fades near and after sunset.

Trivia: did you know that the rain guard accompanying these binoculars can also fit over the objectives! Cool or what?!

During the first week of March, we enjoyed some cold but clear blue sky days, followed by dark, frosty nights. I enjoyed some mesmerising views of a waxing crescent Moon, with its beautiful earthshine illumining the dark face of our natural satellite.  But after the Moon set, I was able to enjoy some wonderful views of seasonal deep sky objects, such as the Pleaides, Hyades, the Alpha Persei Association and the Double Cluster. The super-wide and nearly flat field made observing these extended objects particularly pleasant. Fainter open clusters, such as M35 in Gemini, and the trio of Messier open clusters straddling the mid-section of  Auriga, were also very easy to sweep up in this small binocular.

Later in the night presented opportunities to observe the Beehive(M44) and Coma Clusters (Melotte 111). The excellent colour correction of the GPO Passion ED binocular presents stars in their natural hues, without any colour fringing. I particularly enjoyed glassing some showpiece binocular doubles in Leo, especially Zeta, Gamma and Alpha Leonis. This will make an excellent binocular to observe the full glory of the summer and autumn Milky Way later this year.

Birders will find the GPO Passion ED 8 x 32 to be particularly delightful to use. It’s very wide, sharp, immersive and glare-free field of view, together with its responsive focus wheel, renders it especially versatile in this regard. The superb ergonomic handling of the binocular in my medium sized hands adds yet another pleasant dimension to using this instrument. I feel that its rugged mechanical design and excellent optics will provide first-rate, hassle-free views for many years to come.

How can an instrument of this calibre be offered at such an attractive retail price? I think that’s probably down to the unique cross fertilisation of brains behind the company; founded as it was by professionals from across the leading European optics houses, who bring an eclectic mix of ideas to the table. This, together with the fact that their products are quality controlled in Germany before being shipped out to retailers, gives the consumer much greater confidence of obtaining a quality instrument that will stand the test of time. And that 10 year European warranty ensures that they will take care of your binocular should you hit any snags!

Easy on the eye.

Is there any room for improvement? Yes, I think so! I would have loved to see hydrophobic coatings applied to the outer lenses, which would make it more resistant to the vicissitudes of our mercurial British climate. Since these coatings are now appearing on more economically priced models, I don’t think this is an impossible task for GPO to execute.

Right, that’s your lot folks!

Very highly recommended!

 

Dr Neil English is the author of seven books in amateur and professional astronomy. He hopes to announce some big news in the near future!

 

 

De Fideli.