Product Review: The SvBony SA204 10 x 50 Binocular.

The SvBony SA204 10 x 50 package.

A Work Commenced September 17 2023

Product: SvBony SA204 10 x 50

Country of Manufacture: China

Exit Pupil: 5mm

Field of View: 114m@1000m(6.5 angular degrees)

Eye Relief: 19mm

Closest Focus Distance: 6m advertised, 5m measured

Chassis Construction: Rubber-armoured aluminium

Prisms & Coatings: BaK4 prisms, fully multi-coated

ED Glass: No

Waterproof: Yes, IPX6 rating

Nitrogen Purged: Yes

Dioptric Compensation: +/-4

IPD Range: 53-74mm

Tripod Mountable: Yes

Dimensions: 17.5 x 19.8 x6.4cm

Weight: 925g advertised, 875g measured

Accessories: Padded neck strap, rubber rain guard and objective covers, instruction manual, soft padded case

Price: US $84.99

Ever since its founding in 2009, Svbony has been delighting the astronomy and sports optics community with an expanding range of high-quality products offered at very affordable prices. SVBONY is an acronym which stands for Saturn(S), Venus(V), Birding(B), Optics(O), Nature(N), Youth(Y). I was first introduced to the company a few short years ago when I stumbled on their excellent SV202 ED roof prism binoculars, which have since gone from strength to strength and are now being enjoyed by an army of nature enthusiasts the world over. Not long before this time, consumers were left with very little option to shell out significantly more money for products that often left a lot to be desired quality-wise. Be sure to check out the most recent reviews of these binoculars. Since discovering the SV202s, I have also enjoyed some of their excellent spotting scopes, and regularly use some of their high-quality zoom eyepieces, like the SV191, which I’ve begun to employ extensively this season to observe Jupiter.

The impressive SV 191 7.2-21.6mm zoom eyepiece.

As a dedicated fan of Porro prism binoculars, I’ve steadily come to realise their exceptional value for money owing to great advances in technology, as well as their much simpler design compared with high-performance roof prism binoculars. Truth be told, it takes a lot of knowledge and technology to create roof prism binoculars that can even begin to approach the quality of a traditional, well-made Porro prism design. What’s more, many of the conventional objections purists have laid against the humble Porro prism binocular have now been satisfactorily addressed, including advances in anti-refection coating technology, water- and fog-proofing, and the introduction of modern twist-up eyecups with much better eye relief to accommodate eye glass wearers. In addition, advances in material science also means that good Porro prism binoculars can now be manufactured with lower mass chassis, allowing them to be carried longer in the field.

It was these considerations, as well as my own experiences with several budget-priced Porro prism models that led me to appraise one of Svbony’s newest products, the SA204 10 x 50, a traditional Porro prism binocular. Having ordered several products directly from their online store, I decided to purchase this instrument directly from Svbony too, since they’re currently not available from Amazon UK.

First Impressions  

The Svbony SA204 10 x 50 binocular.

The SA204 10 x 50 package took about two weeks to arrive from the Far East to my home. As usual with Svbony, I was extremely impressed with the attention to detail in how it was packaged during its long trip to the UK. The instrument arrived double boxed inside some bubble wrap to ensure that nothing moved out of place during transit.  All the accessories were also neatly packed away, including the ocular and objective covers, a carrying strap, lens cleaning cloth, a well-written instruction manual and a decent soft padded carry case. Inspecting the binocular, my first impressions were very favourable. The instrument is covered in a high-quality textured rubber substrate, ribbed at the sides for extra grip. The twist-up eyecups moved smoothly and were easy to adjust, keeping their individual positions firmly when clicked into place. Two intermediate positions are available between fully retracted and fully extended, so plenty of options for those who like to experiment.

Belly side up.

The aluminium central hinge is nicely tensioned, allowing you to easily adjust it to your preferred IPD. Once there, it stays rigidly in place. The rubber-covered central focus wheel has deep ridges to afford extra grip. Turning is very smooth with no free play. It ‘s quite stiff though, a consequence I suppose of the instrument being properly sealed and nitrogen purged. The focuser moves the eyepiece assembly up and down with no annoying wobbles I’ve seen in other instruments in this price class. 0.8 turns anticlockwise takes you from closest focus to jut beyond infinity. Eye relief is very generous. I was easily able to engage with the entire field using my varifocals, although I don’t wear spectacles when glassing under normal circumstances.

The dioptre adjustment is made using a small lever under the right eyepiece that rotates either clockwise or counter-clockwise, and I was easily able to find my optimal position. Once set in place, it stays there. I would say it’s very nicely engineered.

The large ocular lenses and twist-up eyepieces are easy to engage with.

The large ocular lenses have nice green multi-coatings and the objectives are decently recessed as all good binoculars ought to be. The objective coatings appear to be significantly more subdued to those applied to the ocular eyepieces and I detected a faint reflection off one of the interior lenses possibly indicative of one surface being singly coated. The rain guard and tethered ocular covers are quite basic but do an adequate job protecting the lenes from rain and dust.

The 50mm objectives have good coatings although there appears to be one surface that may be singly coated based on its appearance in daylight.

The instrument feels really nice in the hand with plenty of wiggle room to engage with my medium-sized mitts, making it easy to hold the instrument firmly. I was pleasantly surprised by the weight of the instrument without the strap and lens covers. Although the specs claim 925g, my SA204 tipped the scales at just 875g or 50 g less than advertised!  All in all, I came away with the impression that this was indeed a nicely appointed binocular, significantly better built than other 10 x 50 Porros I’ve tested in the past, including the Opticron Adventuer T WP and the Nikon Aculon.


My optical testing began by measuring the effective aperture of the instrument by directing my iPhone 11 torch into one of the eyepieces and measuring the size of the resulting circular shaft of light emerging on the other side of the objectives. By tracing a circle of diameter 50mm, I was able to show that the circular light shaft fitted snugly into the circle indicating that the SA204 was operating at its full aperture.

The SA204 10 x 50 operates at its full aperture.

In the next test, I examined how well the binocular handled a beam of bright light. Turning on a sodium street lamp after dark, I was relieved to see that only a few minor internal reflections were seen that were largely non-injurious to the image. There was no diffused light around the light ether. Consulting my notebooks, I reported a little more internal reflections for both the Nikon Aculon and Action EX Porros(both of which retailing for considerably more than the SA204) I reviewed some time back and about the same as I recorded with two models of Opticron Adventurer T, but not quite as good as that seen in the significantly more expensive Opticron Imagic TGA WP(a £200 value).

Looking at the exit pupils yielded quite good results. I recorded nice round circles but I could see some light leaks around the pupils suggesting that better blackening on the inside of the tubes wouldn’t have gone astray.

Left pupil.
Right pupil.

I had the opportunity to test the SA204 in all kinds of lighting conditions. The image is quite good: sharp, nice contrast, with a surprisingly large sweet spot. Colour fringing is very well controlled, especially off-axis.In this capacity, it’s certainly in a completely different league to the Nikon Aculons I tested, which displayed alarming levels of lateral colour to my eyes. Glare suppression is quite good too. I discovered that by retracting the eyecups one notch down from fully extended improved both the visibility of the field stops and the amount of glare I recorded. The instrument has an impressively wide field of view of 6.5 degrees with very well-defined field stops. I did perceive some peripheral softness near the field edges but it was not at all objectionable to my eyes. The instrument does display strong pincushion distortion however. I took the liberty of photographing some pink flowers at a distance of about 30 yards to give the reader an idea of how well corrected the field is:

Flowers imaged obliquely at 30 yards distance. Medium Resolution Image.

Close focus was measured at about 5m, less than the 6m advertised, putting it in the same ball park as a few other 10 x 50 Porro’s I’ve used. Of course, an instrument like this excels under the stars, where the 10x magnification and 50mm objectives pull in a lot of starlight. I checked collimation under the stars by defocusing the bright star Capella using the right eye dioptre while keeping the left barrel image as sharp as possible. The focused star remained well inside the defocused anulus not only in the centre of the field but also when placed to the extreme north, south, west and east edges, indicating very accurate alignment of the left and right barrels. Examining the Alpha Persei Cluster high up in the eastern sky reveals a rich cache of stars scattered across the field, I was delighted to see that they remained acceptably small and sharp across most of the field with only the outer 20 per cent of showing some mild distortion.  But even at the field stops bright stars like Vega and Altair remained quite tightly focused. Moving bright stars to the edge of the field showed little in the way of illumination drop off either. These results were most impressive for a large binocular retailing for significantly less than $100. Indeed, this instrument can be used to very good effect for general stargazing.

I estimated the field size by trying to image Alkaid and Mizar in the Plough, which have an angular separation of precisely 6 degrees 40’ or 6.66 angular degrees. I was unable to keep both stars in the same field of view but only just so, indicating that the advertised field size of 6.5 degrees was quite accurate. Views of the bright waning Moon rising over the eastern hills showed very nice results, with excellent crater detail coming through across the southern Highlands. There were a few minor internal reflections seen around the silvery orb, but they weren’t judged to be too offensive. I could detect a sliver of chromatic aberration at the edge of the Moon when centrally placed in the field  but this could be largely ameliorated by carefully reconfiguring eye placement. Off-axis colour fringing was more obvious though, but nothing I would describe as being out of the ordinary.

There was one negative however, and it manifested itself as I was imaging star fields in the vicinity of some streetlamps. Some of this peripheral light was entering the field, brightening the background sky by a tad. This disappeared however when I moved to the darkest location in my garden away from such light sources. In contrast, my Nikon E II 10 x 35(retailing at nearly ten times the price of the SA204) handled this stray light much more effectively. That said, I don’t count this as a major issue, and Svbony would do well to blacken the inside of the barrels that little bit more effectively.

Aperture Wins!

Comparing the Svbony Sa204 10 x 50(left) and Nikon E II 10 x 35(right) under the starry heaven.

Lest anyone be uncertain about the benefits of aperture, I took the opportunity to test both the SA204 10 x 50 and Nikon E II 10 x 35 under a dark country sky with no Moon during the wee small hours of September 17. Turning the instruments on the faint galaxy duo M81 & M82 in Ursa Major, I did manage to see them in both instruments, but they were much easier to see in the 10 x 50. The same was true when I moved the instrument to the celebrated Double Cluster in Perseus, now passing near the zenith at about 2.00 am local time. The view was compelling in both instruments, but the clusters were considerably richer in the larger glass. Ditto for the wondrous Pleiades and Hyades in Taurus as well as tracking down the trio of Messier open clusters in Auriga still low in the east. Indeed, I was quite impressed by just how well the SA204 managed to image the Hyades, with its constituent stars filling most of the field. I noted how well defined fiery red Aldebaran presented itself when positioned at the south-eastern edge of the field! All this to show that ‘you cannae change the laws o’ physics captain’ no matter how sexy and optically pristine the smaller, more expensive glass may be.

Conclusions and Recommendations

Great bang for buck!

The Svbony SA204 10 x 50 represents excellent bang for buck. It serves up a well corrected, sharp, bright and high contrast image with good control of chromatic aberration. It will serve as a fine general-purpose binocular, where it excels at low light observations and astronomy. I would have been thoroughly delighted with an instrument like this were I starting out in binocular astronomy again. I would however recommend using a more substantial neck strap than the generic one supplied with a chunky instrument like this. Better attention to internal blackening to improve contrast when observing under bright night lighting would also go a long way to making it an even better performer. That said, if you’re after a cost-effective instrument that does many things well, I would certainly recommend this neat 10 x 50 Porro to all and sundry.

Dr Neil English’s new 650+ page book, Choosing and Using Binoculars: A Guide for Stargazers, Birders and Outdoor Enthusiasts, caters for all budgets and will soon be published in paperback. Now available for pre-order.  

De Fideli.

A Fresh Look at the Celestron SkyMaster 15 x 70.

The Celestron SkyMaster 15 x 70.

A Work Commenced October 14 2022

Though the Celestron SkyMaster 15 x 70 was introduced a few decades ago, several clones of this highly successful product have come and gone over the years. Indeed, back in my days when I was a professional astronomy writer and telescope reviewer, I briefly got caught up in the new fad of using cheap clones of the Celestron offered by Revelation Astro, for example, which I bought in and briefly played around with. I do remember one unit arriving out of collimation, while the other delivered only so-so images that simply didn’t engage me. You see, I just had no enduring interest in binoculars for much of my early career. But how times have changed!

In preparing for the writing of my book, I decided to buy in the latest rendition of this binocular for a fresh look. I was quite impressed by the package and the build quality of the instrument, especially when you factor in the very modest cost of this big binocular – of the order of £85. The instrument is covered with a durable black rubber armouring that affords excellent grip when hand-held.  While it’s unquestionably a large binocular, it’s not all that heavy. My sample tipped the scales at 1251g, so quite light for this configuration.


During the day, the SkyMaster 15 x 70 produced bright and sharp images, with surprisingly good contrast. I could instantly see how it’s so popular as a long-range optic, for studying targets in the far distance. Indeed, I can see it serving well as an alternative to a low power spotting ‘scope. Collimation was perfect – unlike what I’d seen on some of the Revelation clones I had used in the past – and close focus was measured to be about 15.5 yards. The central focus wheel is covered in textured rubber and rotates very smoothly with no free play or backlash. The dioptre adjustment is located under the right eyepiece. It moves with a fair amount of friction, ensuring it won’t wander easily during ordinary use.

The large central focus wheel moves smoothly without any free play.

The large achromatic doublet objective has immaculately applied multi-coatings contributing to the bright image and high contrast views. This is undoubtedly helped by the longer than average focal length of the objectives on this instrument – 280mm  – making it a solid f/4 relative aperture. The SkyMaster has a big sweet spot in the centre of the image but does show significant softening at the edges of the field, mostly in the form of field curvature. Of course, a large light cup like this really shines under a clear, dark sky. To get the best use out of it, it needs to be stabilised on a monopod or lightweight tripod. The package I received also included a decent quality tripod adapter to get you started, but a quick rap test introduced too much vibration in the mounted instrument which took quite a few seconds to dampen down, so I’d strongly encourage folk to invest in a higher quality unit, made out of machined metal rather than the hard plastic unit supplied with the binocular.

A big bino like this really benefits from a good, sturdy tripod or monopod.

Examining the exit pupils of the instrument, I was delighted to see that they were round and untruncated, as you can see below.

The left exit pupil.

The right exit pupil.

When I directed a bright light through the ocular lens and measured the size of the resulting disk projected onto a flat surface, I measured its diameter to be about 63mm. That didn’t come as a big surprise though, as these budget instruments are known to have stopped down optics. I did not however consider this to be a serious handicap though, as the instrument still lets through a large amount of light. In another test, I looked for ghosting and internal reflections by turning the SkyMaster 15 x 70 on a bright sodium streetlamp in the distance. I did detect some minor reflections, but they weren’t that prominent based on what I had already seen in some other instruments I’ve tested – sometimes costing significantly more.

Those big objective lenses gather a surprising amount of light.

Star testing on bright stars showed that the inner 50 per cent of the field shows very nicely focused stars, but as one moves further out, the effects of field curvature, astigmatism and coma gradually increase. The outer 20 per cent of the field is pretty much unusable, but that’s a small trade off considering what the binocular can show in the middle of its wide, 4.4 degree field of view.

Let me elaborate.

Views of the Moon are spectacular in the Celestron SkyMaster 15 x 70. Its intensely bright silvery surface is tack sharp in the centre of the field, with excellent contrast. A very minor amount of chromatic aberration could sometimes be glimpsed at the centre of the field, but I found that it was very sensitive to eye placement. Internal reflections were very minor and weren’t in the least bit intrusive on this bright celestial target. The vast crater fields of the southern highlands were beautifully rendered, as were the mountain ranges and ray craters peppering its ancient and battered surface. This will be an excellent instrument for observing earthshine on the crescent Moon when it’s particularly prominent during the months of March and April.

With a steady view, I was thrilled to be able to make out the tiny globe of Saturn, as well as its magnificent ring system. Jupiter can also be glimpsed as a tiny globe together with its four large Galilean moons. Try as I may though, I was unable to glean any details form its oblate disk. At this low magnification – from a telescopic perspective at least – the giant planet is simply too bright to resolve any surface details. However, you can watch the satellites change from hour to hour and from day to day.

The very generous field of view is perfect for framing large open clusters. The Pleiades is stunning through this large binocular, as is the Double Cluster in Perseus and the Beehive Cluster in Cancer. Following the sky south of Albireo(Beta Cygni), the Celestron SkyMaster 15 x 70 served up an excellent view of the Coathanger asterism. I enjoyed a spellbinding view of the Sword handle in Orion  in the wee small hours of a chilly October night, the sheer brilliance of the belt stars and the great Orion Nebula beneath them presenting a very compelling binocular portal. From a good, dark rural sky, stars of at least the 10th magnitude of glory can easily be made out.

Another great use of this 15 x 70 is white light solar observing. The 15x magnification provides a very decent-sized solar disk to allow you to clearly see any sunspots present on its surface. I’ve used my own home-made filters fashioned from a sheet of Baader Astrosolar material, placing them over the large 70mm objectives to get excellent views of our life-giving star.


In summary, for the modest price paid for this binocular, the Celestron SkyMaster 15 x 70, certainly represents great value for money. Some critics have noted that many of these units get whacked out of collimation all too easily. Fortunately, re-collimating this instrument is relatively straightforward, using a simple screwdriver to turn two screws (one for vertical movement and the other for horizontal adjustments) which are easily accessed under the rubber armouring of the binocular. You can find several YouTube presentations to see how it’s done. Doubtless, a savvy and resourceful individual can achieve a great deal with this economically priced instrument, whether it be deep sky observing, comet hunting, solar observing or studying a bird’s nest from afar. It’s simply imagination limited!


Neil English’s new book, Choosing and Using Binoculars: a Guide for Stargazers, Birders and Nature Enthusiasts, hits the shops in late 2023.



De Fideli.

Product Review: GPO Passion 8 x 56.

GPO Passion 8 x 56.

A Work Commenced September 23 2022

Product: GPO Passion 8 x 56

Country of Manufacture: China

Chassis: Rubber armoured magnesium alloy

Exit Pupil: 7mm

Eye Relief: 20mm

Field of View: 126m@1000m(7.35 angular degrees)

Close Focus: 2.3m advertised, 2.14m measured

Prism Type: Abbe-Koenig

Coatings: Fully broadband multi-coatings, phase correction coatings on Abbe Koenig prisms

Light Transmission: 92%

ED Glass: No

Waterproof: Yes

Nitrogen Purged: Yes

Weight: 1245g advertised, 1257g measured

Dimensions: 19.2 x 15.8 cm

Accessories: Instruction manual, cleaning cloth, hard, case, neoprene neck strap, hard case strap, objective covers, ocular covers and warranty card.

Warranty(European): 10 Years

Price: UK £589.00

In previous blogs, I reviewed some excellent quality binoculars from the new German-based company, German Precision Optics(GPO). In these reviews I was very impressed with the outstanding build quality of their products, not to mention their excellent optical quality. But GPO have not just settled on securing a solid niche in the compact and mid-sized binocular market, they have also developed larger aperture models specifically designed for low light work and astronomy; enter the GPO Passion 8 x 56 and 10 x 56 series.

I acquired a 8 x 56 unit on loan from Steve at First Light Optics for testing and evaluation, and I must again say how delighted I was to see that GPO really are delivering excellent value for money in this competitive corner of the sports optics market.

The instrument arrived in a beautiful presentation box, as shown in the photo above. The binocular was set rigidly in place in the cut-out foam section and lying adjacent to it, the beautifully designed hard case to store the instrument. Inside the case you’ll find the usual accessories; padded neoprene logoed neck strap, carrying strap for the case, a comprehensive multi-language instruction manual and microfibre lens cleaning cloth. If you take the case out, you’ll also find the 10-year European warranty card for the instrument.


The GPO Passion 8 x 56 is one chunky instrument and you immediately get the feeling of quality the second you prize it from the box. This larger instrument is a scaled up version of the 42mm and 32mm Passion ED binoculars, with a magnesium alloy chassis overlaid by a nicely textured black rubber armouring.

The distinctive curves of Abbe-Koenig optics are abundantly in evidence at first glance.

Tipping the scales at 1257g, this is not an instrument that many would happily trek with all day long; unless you’re Hulk Hogan.

The underside of the GPO Passion 8 x 56. Note the absence of thumb indents which aren’t really necessary anyway.

It’s designed to be used for short hand-held viewing but mostly for tripod mounted activities, such as hunting in low light or watching the stars The focus wheel is covered in a textured black rubber which is easy to grip, rotating just over one full revolution anti-clockwise from nearest focus to just beyond infinity. Though I have reported a small amount of free play in a smaller 10 x 32 GPO Passion ED in a previous review, I was pleased to see that there was none apparent on the focus wheel of this 8 x 56 model.

The beautifully machined aluminium twist-up eyecups are amongst the best in the industry.

A closer inspection of the shape of the barrels betrays the nature of the prisms used in this binocular; the large Abbe-Koenig roof prisms that deliver higher levels of light than standard Schmidt-Pechan prisms incorporated into the smaller GPO models. It’s these Abbe-Koenig prisms that contribute to the weight and the length of this binocular, but it’s all the more remarkable that this optical design is incorporated into this low light binocular at this price point. These prisms are notoriously difficult to make well and are usually only found in instruments costing at least twice as much as this 8 x 56 costs.

The beautifully machined twist-up aluminium eye cups are covered in soft rubber for very comfortable viewing. Four positions are offered to suit most anyone’s requirement for eye relief. I’ve said it before and I’ll say it again: these are amongst the best eye cups ever designed by any binocular manufacturer, period. I was easily able to access the entire field of view with eyeglasses, so absolutely no worries there. The dioptre adjustment is accessed by turning a ring under the right ocular. It moves smoothly but with considerable tension, ensuring it won’t easily be moved out of position in field use.

The proprietary broadband multi-coatings present with a fetching purple hue in broad daylight and are immaculately applied. Viewed head on, they make the lenses almost disappear. The instrument is dry nitrogen purged internally and o ring sealed to prevent fogging up of the internalized optics. It’ s also waterproof, but GPO don’t mention to what degree it will withstand water immersion.

The view of the ocular lenses and focus wheel from above. Check out the beautifully applied antireflection coatings as seen in broad daylight.

The reader may be surprised to learn that, unlike the smaller ED models, the larger 8x and 10 x 56 models do not contain ED glass. GPO believe it wasn’t necessary to incorporate extra low dispersion glass in these models because their main use was in low light conditions, when seeing any colour in a given target becomes difficult to discern, so there would be little advantage in employing an ED element which would have significantly increased its production cost. Having enjoyed many hours testing the instrument both in low light situations and under the stars at night, I can only agree with their design philosophy, as I shall report on a little later. All in all, the build quality and ergonomics of this 8 x 56 are exemplary, and quite in keeping with the other models I’ve reviewed from both their ED and HD lines in the past.

The large objective lenses on the GPO Passion 8 x 56; note how the glass almost disappears when viewed from certain angles.

Optical Testing

My first optical test involved shining a bright light source into the binocular and examining the images produced. I detected a few minor reflections but nothing too intrusive. Diffraction spikes were very subdued and there was very little in the way of diffused light around the light source, indicative of good, homogenous glass. Turning the binocular on a bright streetlamp after dark did show a few minor internal reflections as I anticipated, but by and large I was quite happy with the result. Placing the lamp just outside the field of view showed very little in the way of stray light intrusion; an impressive result compared with many other similar tests performed on other binoculars.

Examining the exit pupils also yielded good results, as shown below. The large 7mm exit pupils were perfectly round with little in the way of extraneous light around them. I did pick up some light leaks well away from the pupils though, a consequence of using Abbe Koenig prisms perhaps? Thankfully they appeared to make no material difference to the images garnered by the instrument, in daylight at least.

Left exit pupil.

Right exit pupil: note the arc of light away from the pupil at lower right.

Testing the binocular out on a bright, sunny afternoon revealed very impressive images right from the get-go. The view is razor sharp inside its very large sweet spot, with only a small amount of softening of the images noted near the field stops. Contrast is excellent.  Scanning a large swathe of trees at the edge of a forest proved to be a very comfortable experience and extremely easy on the eyes, with no blackouts or the rolling ball effect, kept under control courtesy of a modest amount of pincushion distortion near the field stops. Colours are very vibrant in this big glass and I immediately noted the warm tone of the images – very much like those I reported on the smaller ED and HD models. Indeed, I had long wondered whether this warm colour tone was a manifestation of the ED glass utilised in the smaller GPO binoculars or just from the coatings used. I now think it has more to do with the latter than the former.

Glare suppression is excellent in the GPO Passion 8 x 56. It stubbornly refused to show any on bright autumnal days, and also on grey overcast days in the open air. Veiling glare was also exceptionally well suppressed in this instrument too; a testament to the excellent coatings applied to the lenses and prisms, as well as the baffling used throughout the optical train. Close focus was also very surprising. I measured it at just 2.14m, so slightly better than the advertised 2.3m. I consider that amazing for such a large glass!  Chromatic aberration was also very well controlled in this unit. There is a small amount visible on high contrast targets, such as imaging the side of a telephone pole against a bright overcast sky. Lateral (off axis) colour is a bit more pronounced in this large aperture instrument though, as I openly expected, but I felt it was perfectly acceptable given the modest price tag of this instrument. Overall, I would rate the daytime images as quite excellent.

Testing its low light capability, I compared and contrasted it with the views through my excellent Opticron Imagic TGA WP 10 x 50 Porro prism binocular. I found the views very comparable until about a half hour before sunset on September evenings, with the 8 x 56 pulling noticeably ahead on selected targets under poorly illuminated hedgerows as the last rays of sunlight dipped below the horizon. By about a 40 minutes after sunset, the 10 x 50 was really struggling in comparison with the 8 x 56.

Under the Stars

I was dying to find out how the GPO Passion 8 x 56 would perform under a dark, clear sky at night, and I wasn’t disappointed here also! In fact, the views were absolutely stunning! The very generous field of view effortlessly frames wonderful star fields. Bright stars such as Vega and Aldebaran are rendered in their natural colours. Chromatic aberration was a non-issue in the inner 50 per cent of the field, and only showing mild splashes of bluish purple as the stars were moved to the outer part of the impressively large field of view. Fainter stars were examined to see how well they maintained their pinpoint sharpness. I was very pleased to see that they remained impressively small and tight across about 75 per cent of the field, with some mild field curvature beginning to show up thereafter. Only in the last 10 per cent of the viewing portal, could I make out  a small amount of astigmatism and coma creeping in.

I was genuinely surprised how long I could hand hold the binocular while scanning the Milky Way through Cygnus, Perseus and Cassiopeia. The low power of 8x definitely helps in this regard. For more serious studies though, I resorted to mounting the instrument on a light weight monopod. Views of the Pleiades and Hyades in Taurus were simply stunning, its impressively high light throughput presenting very faint stars quite invisible to a 42mm model. In fact, this instrument threw up some of the best binocular views of the heavens I have personally experienced. I enjoyed exploring many early autumn open clusters, such as the M36, 37 and 38 spanning the mid-section of Auriga. M 34 in Perseus and the great globular cluster in Hercules (M13) in this large binocular light bucket. Mighty Jupiter, now prominent in our night skies, was dazzlingly bright, with its four giant moons being easily seen. Fiery red Mars was also stunningly presented in Taurus against a jet black sky.  The Alpha Persei Association and Double Cluster in Perseus were breath-taking in this binocular too. Rising up in the wee small hours of late September, I was treated to some extraordinary views of Orion; with the white and blue-white Belt stars shining brilliantly, and below them, the famous Sword Handle of the celestial Hunter, with the magnificent Orion Nebula blazing forth across the light years. The excellent light gathering power of the GPO 8 x 56 allowed me to follow much fainter tendrils of nebulosity than I could make out in a optically excellent 7x 50 Porro prism binocular, though I must concede to yearning at times for a look through its higher power sibling; the 10 x 56, which probably would have totally blown me away lol. All of these experiences only consolidated what I had seen during the day: this is an excellent low light/astronomy binocular that would satisfy the most discriminating of observers.

Bon Voyage!

So, here we have yet another GPO binocular offering exceptional ergonomics and really good optics for a very decent price. I say this in light of a cursory examination of other 8x or 10 x 56 models, built around Abbe-Koenig prisms. The Zeiss Conquest HD 8 x 56, for example, has a build quality quite comparable to the GPO Passion, but its field of view is slightly smaller(125m@1000m), its weight slightly heavier(1265g),  its eye relief lower(18mm), its close focus distance much longer(3.5m), and possesses a light transmission of 90 per cent, lower than that of the GPO Passion, even with ED glass. But that instrument retails for more than twice the price of the big GPO light bucket! Or consider the fluorite containing Maven B5 10 x 56 costing a few hundred pounds more than even the Zeiss Conquest HD but with the same light transmission as the GPO Passion(92 per cent or so). Seen in this light, the GPO Passion 8 x 56 offers tremendous bang for buck and absolutely deserves great success in the burgeoning sports optics market.

Highly Recommended!

Dr Neil English explores many more hot bargains in his up-and-coming book, Choosing & Using Binoculars: A Guide for Stargazers, Birders and Nature Enthusiasts, due out in late 2023. 

My sincere thanks to Steve at First Light Optics for kindly lending me the instrument for field testing.

De Fideli.

Two Low Light Binoculars Compared: Opticron Imagic TGA WP 7 x 50 vs 10 x 50.

The Opticron Imagic TGA WP 7 x 50 & 10 x 50.

A Work Commenced August 26 2022

Preamble 1

Preamble 2

Preamble 3

Preamble 4


There’s been many highs and lows on my 4-year journey through the wonderful and sometimes weird world of binoculars. Arguably the greatest high for me was my re-discovery of the many charms of Porro prism binoculars. Yet, it’s certainly the case that these instruments have been unfairly demurred for reasons that continue to baffle me. The simple truth is that a well-made Porro prism binocular can produce outstanding images using relatively simple technology compared with roof prism models that never seem to stand still. Almost every other week a new model hits the market promising out-of-this-world performance at out-of-this world price tags. I spent more than three years testing all manner of roof prism instruments without ever giving a thought to the humble Porro prism binocular- apart from the quirky reverse-Porro design of the Pentax Papilio II. Why? I supposed I swallowed hook, line and sinker the urban myth that the latter were simply inferior just because they were cheaper. After all, you get what you pay for, right? I mean, how could a full-featured Porro prism binocular costing a couple of hundred pounds realistically compete with a sexy, streamlined roof prism model costing a cool grand or more? Fortunately, I’ve spent the last six months buying in and testing some really nice Porro prism binoculars, and these collective experiences have consolidated my preference for these over their roof prism counterparts.

And I appear to be in good company.

UK-based Opticron is to be lauded for keeping high quality Porro prism binoculars alive and well in the 21st century. As one of my main birding binoculars, I enjoy the excellent quality views of the now discontinued SR.GA 8 x 32 which delivers very similar though not quite as stellar views to my favourite instrument; the superlative Nikon E II 8 x 30, which I tend to baby just a little owing to its lack of rubber armouring.

But that got me thinking about what higher power instrument to use for the dull days of Winter and/or for longer range work, but most especially as a general purpose astronomical instrument to be used during our long, dark(and often cold) winters  here at 56 degrees north latitude. I had enjoyed a high quality 10 x 32 for a while but it lacked the light gathering power of bigger 10 x 42 models, which I also seriously considered. I had contemplated using the Opticron Adventurer T WP 10 x 42, a larger format Porro, but instead I decided to buy in and test two intriguing 50mm instruments from the same company – the 7 x 50 and 10 x 50 Imagic TGA WP models – to field test and learn as much as I could about them. I’ve been testing both of these instruments in various conditions, by day and by night, both at home here in Scotland, and while on vacation in south Wales, and have been so impressed with them that I decided to hold onto one model – the 10 x 50 – as I now firmly believe that it will do everything a 10 x 42 model can do, only better! To see why, read on!

A Closer Look at the Ergonomics of the Instruments

As outlined in Preamble 1 above, I had previously acquainted myself with the many delightful features of the Opticron Imagic TGA WP in the smaller 8 x 32 format, which is now in the capable hands of a keen lady birder on Jersey, in the Channel Islands. I was delighted to see these larger instruments had precisely the same features. Porro prism binoculars are not generally known to be waterproof, and this is one reason cited by some for rejecting them for serious field use. These instruments are o ring sealed and purged with dry nitrogen gas, so that traditional excuse is no longer valid.

Both 50mm models are waterproof and nitrogen purged.

“I don’t like the old-fashioned rubber eye cups on those classic Porros,” I hear you say.

These Imagic TGA models have fully modernised twist-up eyecups that click solidly into place and hold their positions firmly.

Check out the excellent rubber armouring and solid twist-up eyecups on these 50mm models.

What about eye relief? That’s quite poor in classic Porros isn’t it? Not on these models; the 10 x 50 has 19.5mm of eye relief and the 7 x 50 has a full 21.5mm. That’s ample for any eyeglass wearers. And yes, I’ve tested them both using my own eyeglasses and both present the full field in complete comfort.

“What about the dioptre mechanism? Isn’t that the usual ring under the right ocular?”

No, these models possess an ingenious click-stop mechanism. The ring has an unusually high degree of tension and clicks its way round to your preferred setting. Once there, it clicks into place and doesn’t budge: just as effective as any locking dioptre setting featured on much more expensive roof prism models. What an excellent piece of applied engineering! Incidentally, fellow author, Stephen Tonkin, a highly experienced astronomy binocular enthusiast(see Preamble 2 above), whose opinions I trust, referred to the dioptre as being ‘very stiff.’ That’s true, but he likely under-appreciated this feature for daytime uses, when dioptre settings are more likely to wander.

The right eye dioptre is ingeniously engineered, clicking into place firmly and quite incapable of being accidently moved.

“Oh but Porro prism binoculars are big and clunky right?”

Ah, no, both of these instruments tip the scales at just over 800g. The 7 x 50 weighs 823g, while the 10 x 50 weighs just one gram more. That’s lighter than some of the heavier 42mm roof prism models I’ve tested, and for a 50mm specification, these are reassuringly lightweight.

“Yer but they’re awkward to handle!”

Nope, these instruments are exceptionally easy to handle. The weight is brilliantly balanced in my medium sized hands. Indeed, both instruments rate very highly in terms of pure form factor. They feel great in the hand.

“What about the armouring? I’ve heard this can be a bit skimpy on classic Porro models.”

Maybe on older models, but not on these. Both are endowed with a good, thick, protective rubber armouring, with upraised ridges for exceptional grip, even in wet weather.

“OK, OK, but they just don’t look as cool as roof models.”

Oh please; don’t be so shallow!

Ocular & Objective Lenses

Both instruments are fully multicoated and treated with the company’s proprietary differential  F coat to minimise glare and internal reflections. The objectives are nicely recessed to protect the instrument from rain, dust and stray light. Check it out below:

Nothing shallow about these: the beautifully applied anti-reflection coatings applied to the deeply recessed objective lenses.

The ocular lenses are large and easy to engage with.

The ocular lens with eyecups fully retracted.

There is only one significant physical difference between the two instruments, and it pertains to the size of the eyepiece lenses. The 10 x 50 has a 21mm diameter, while the 7 x 50 lens measures only 18mm.

The ocular lenses are larger(21mm) on the 10 x 50 model, compared with 18mm for the 7 x 50.

The focuser on both instruments is exceptionally smooth and backlash free in either direction: very similar if not identical with my smaller SR.GA. 8 x 32. Tension is perfect for my taste – excellent in fact! It takes just three quarters of one revolution anticlockwise to go from near focus to infinity, and beyond.

Tripod/monopod compatible?

Yep, just unscrew the cap at the head of the bridge, mate it to a good quality tripod/monopod adapter and you’re off to the races!

Both binoculars have a decent IPD range: 57 to 73mm, so even smaller faces can engage with them easily.

What about accessories?

Well, you get a basic but perfectly functional rain guard that can be attached to the strap if you like it that way. I don’t like any appendage hanging from my optics so I usually carry it in my jacket or trouser pocket if its raining or threatening to do so. The objective caps are basic plastic covers but they fit tightly.

The carry case accompanying both instruments is well made from faux leather. It is lined internally and has enough space to carry the binocular with its strap attached

Both instruments come with a very nicely designed case which very adequately protects your investment.

The instruments fit snugly inside the supplied carry case, even with the strap attached.


Optical Assessment: 

I measured the effective aperture of both instruments simply by shining a bright light through the ocular lenses and measuring the size of the circle of light projected on a flat surface. Both showed no evidence of stopped down optics with effective apertures of  about 49mm for both the 7x and 10x instruments.

Next I examined the exit pupils of both instruments. Both delivered satisfactory results. Shown below is the results for the 10x instrument.

Right exit pupil.

Left exit pupil.

Both pupils are perfectly round, so no truncation here. There is some light outside the exit pupil but this had very little effect in practice, as my subsequent tests showed.

Placing an intensely bright light at a distance of about 5 metres and examining the focused images through both instruments produced pretty much identical outcomes. Both showed very good results, with only a few minor (read very low intensity) internal reflections, no diffraction spikes(as expected with Porro models) and no diffused light around the beam, all indicative of high quality, homogeneous glass. Testing on a bright sodium street lamp after dark showed excellent results too – again clean with no annoying internal reflections. So far, so very good!

In agreement with all of the reviewers cited in Preamble 2, 3 and 4  above, the daytime images delivered by these binoculars are very impressive. Both deliver very bright, high-contrast images, with very large sweet spots. Even the edges near the field stop are satisfyingly sharp. Colours are very faithfully represented and appear neutral to my eye. Chromatic aberration is very well controlled. It’s pretty much non existent for the most part but a trace can be seen when viewing roosting corbies perched high on treetops against a grey sky background. A small but very tolerable amount of lateral (off axis) colour can also be witnessed when viewing branches near sunset against an overcast sky. Incidentally, the light transmission of these instruments was measured by allbinos to be in the region of 88 per cent, so these are very efficient light cups which will prove especially useful for my primary use for them – astronomical viewing.

Glare suppression is excellent too. Indeed, when comparing the images in both my Japanese-made SR.GA 8 x 32 and the Imagic TGA 7 x 50, I judged the latter superior in this regard. On dull afternoons, for example, glare usually manifests itself in most binoculars when glassing in the open air, in the direction of the Sun. Under these conditions, the 7 x 50 produced a slightly more contrasted view when imaging a hill top. Veiling glare was also slightly better controlled in the 7 x 50 Imagic TGA too. You can readily test for this by imaging the topmost boughs of a tree against a bright overcast sky with the Sun nearby. Indeed, consulting my notes on the smaller 8 x 32 Imagic TGA model,  I had already noticed this when I briefly compared it to my newly-acquired SR.GA.

This may come as a surprise to some readers, as the SR.GA  is arguably one of the best modern compact Porros available until recently(they replaced Opticron’s excellent HR series you’ll remember). I understand the Imagic TGA models are also Japanese-designed but are actually manufactured in China. So what’s going on here? I think it’s the coatings applied to the lenses and prisms on the Imagic TGAs. These were introduced later than the SR.GAs and so may have benefitted from slightly better coating technologies. Just a hunch, but I’ve yet to come up with a better explanation!

I took some images with my Iphone 7 hooked up to the 10 x 50 Imagic TGA, using my Nikon EII 8 x 30 as a control and comparison. Both are 10-burst images taken with a 3-second delay to reduce vibrations. They were taken just a few minutes apart on the afternoon of August 27 2022. The results are shown below:

Image through the Opticron Imagic TGA WP 10 x 50.

Image captured through the Nikon E II 8 x 30. 

  • The reader will note that the field of view of the 10 x 50 is 5.3 angular degrees (confirmed later by measurement). The Nikon E II 8 x 30 is a world-class compact Porro with a stupendously wide field of 8.8 angular degrees.

You can make up your own mind about these images.

Notes from the Field

Both these large aperture binoculars are extremely comfortable to look through, with no blackouts experienced while panning across a landscape. Close focus on the 7 x 50 was measured to be 5.6 yards while the 10 x 50 was slightly longer at 5.9 yards. Both instruments present nice, well defined field stops, as well as instantly recognisable stereopsis. This is especially noticeable when viewing  objects in close proximity to each other, such as in a forest, with the 10x glass being a little bit more pronounced in this regard. This is yet another feature I find particularly charming about Porro prism binoculars in that they readily deliver views with more spatial information owing to the larger separation of the objectives than in their roof prism counterparts. I had a particularly vivid experience of this stereoptic effect in the very early morning of August 7, when I sat, completely enchanted, observing a magnificent dragonfly hovering over my brother’s garden pond in South Wales. The mist was still dissipating from the water’s surface in the cool of the morning, as I watched in sheer amazement as its iridescent wings, bulging compound eyes and body glistening in the feeble, hazy sunshine some 10 metres in the distance. I became totally captivated by the dexterity with which it manipulated its two sets of wings, changing both their orientation and power stroke from moment to moment before accelerating at breakneck speed off into the distance. I later found out that these giants of the flying insect world have been clocked moving at more than 18 miles per hour!

“How wondrously designed these creatures are,” I thought to myself. Small wonder they’ve served as the inspiration behind drone technology and a whole raft of artificial visual systems that enrich human life.

The 7 x 50 gives an ultra-stable viewing experience owing to its lower power, allowing the user to view for significantly longer periods of time. That said, I found viewing through the 10x glass to be the more immersive of the two, despite its smaller field of view(5.3 degrees as opposed to 6.0 degrees for the 7x 50). Depth of field is noticeably deeper in the 7x instrument though. Indeed, having both instruments readily at hand, I conducted some measurements of this with the help of my son’s golf rangefinder. Carefully targeting well defined objects in the centre of the field to minimise the effects of field curvature, the 7 x 50 unit delivered a close focus at infinity of 50.9 yards, while the 10 x 50 produced a value of 70.5 yards.

In previous work, I fleshed out some of the details of the factors that influence depth of field, showing that the most important parameter was magnification and which scales inversely with power. I thus expected a (10/7)^2 or two fold greater field depth in the 7x 50. Plugging the figures in yielded (70.5/50.9)^2 = 1.92, in close agreement with theory.


Large aperture instruments such as these naturally come into their own in low light situations, such as late evening viewing. Observing at sunset, and about half an hour into the dusky twilight, I was readily able to discern that the 7 x 50 yielded brighter images of targets set in the shade, such as leaf litter under bushes. But here’s the thing; I was very impressed by how well the 10 x 50 was keeping up! Magnification is, of course, at play here, providing a more enlarged view of targets which partially compensates for the grater brightness of the lower power glass. I mean, what good is a brighter image if it doesn’t show detail? You can find more on this interesting topic here.

Ad Astra

Although I could more or less instantly tell both instruments were well collimated in daylight tests, I was easily able to verify this under the stars. Centring the bright star Altair in both the 7 x 50 and 10 x 50, I turned the dioptre setting to the end of its travel, defocusing the star from a tight pinpoint to a defocused anulus of light. Both instruments showed the focused star well inside the anulus, indicating that both instruments had their barrels well aligned.

Turning to the Big Dipper, I took the opportunity to test the size of the field of view in the 10x glass by noting that the pointer stars(which show the way to the North Star, Polaris), Dubhe and Merak are precisely 5 degrees 21′ apart, or 5.3 angular degrees. I was delighted to see that both stars could just fit inside the field of view, so no discrepancy here with the stated field size. Impressive!

While I was in this part of the sky, I took the opportunity to hunt down the two Messier galaxies in The Great bear – M81 and M82  – easily swept up by drawing an imaginary line from Phecda through Dubhe and extending that line as far again until I could see both galaxies close to each other in the same field of view. Comparing the views in the 7 x 50 and 10 x 50, it was immediately obvious that the 10x glass showed these faint fuzzies considerably better than the 7x glass. This is all textbook behaviour for these binoculars. The 10x glass delivers ~ 0.5 magnitude boost over the 7x glass. The main reason is the larger magnification of the 10 x 50, which darkens the sky approximately (10/7)^2 or 2x greater than the 7 x 50, making these faint objects stand out better in the former. This is a very convenient way to see the immediate benefits of a 10 x 50 over a 7x 50 under dark skies.

But it was also obvious when I turned the binoculars over to the Alpha Persei Association in Perseus, where the 10 x 50 swept up more stars than the 7 x 50. The same was also clear from looking at the Double Cluster, located roughly midway between Cassiopeia and Perseus. Fainter stars could be seen in the 10x glass than the 7x glass.

Bringing both the 7x 50 and the 10 x 50 to a very dark site in rural South Wales during warm and settled summer weather afforded ample opportunities to do some quality stargazing. For the steadiest, deepest views, a monopod is recommended with either of these instruments, but on this occasion, I enjoyed simply hand-holding them while lying back on a zero gravity chair. Views of the Milky Way through Cygnus were breath-taking in both binoculars, particularly in the region around Sadr. What I really like about these binoculars is their very well corrected fields. As I’ve stated before, optical defects are much easier to see under the stars than during the daytime, when the eye tends to be overwhelmed by the amount of detail seen in and around the centre of the image, but star images are less forgiving. Under some super dark skies and the Moon setting early in the first week of August, I could see that the central 80 per cent or so of the field of these binoculars produced sensibly perfect star images, but in the outer 20 per cent, the effects of field curvature began to manifest themselves. Thankfully, these aberrations were very mild(as you can see from the photos taken above), with the images nearly all the way up to the field stops still being acceptably small and sharp to my eyes. Indeed, the views very much reminded me of those served up by my largest binocular – the Pentax PCF 20 x 60 WP, with its aspherical eyepieces – only with a much wider field( 5.3 compared with just 2.2 degrees).

Images of the Moon in both binoculars displayed excellent contrast and sharpness, and I could detect very little in the way of chromatic aberration in the centre of the field, with lunar craters peppering the southern highlands with impressive clarity. Off axis, a small amount of lateral colour (mostly yellows and a splash of purple) began to creep in but that’s all par for the course in most any 10 x 50 you’ll look through.

The formidable light gathering power of these high-quality Porro prism binoculars from Opticron proved very beneficial for enjoying the colours of bright stars. I enjoyed some magnificent views of the Pleiades in the wee small hours of late August, as well as M34 in Perseus, and the ghostly light from the Great Spiral Galaxy in Andromeda(M31). The Dumbbell Nebula(M27) in Vulpecula looked terrific too in the 10 x 50 but less impactful in the lower power of the 7x glass. The same was true when I turned the instruments on the Coathanger asterism(Brocchi’s Cluster) nearby. And moving back across the sky into Cassiopeia, I compared and contrasted the view of the ET Cluster in both instruments, with the victory, once again, going to the 10 x 50.

The excellent sharpness and contrast of these binoculars proved ideal for observing colourful single, double and multiple stars, with the 10 x 50 coming out on top once again. Mu Cephei – Herschel’s Garnet Star – was compelling in deep red, as were the beautiful colour contrast binocular doubles O^1 Cygni and Delta 1 & 2 Lyrae sailing high in the late Summer sky. Colourful stellar associations, such as brilliant white Altair contrasted against the  orange giant star, Tarazed, in the same field, were admired in all their preternatural beauty.

The Vortex Diamondback HD 10 x 50 is no match for the Opticron Imagic TGA WP 10 x 50.

I’m of the opinion that star images are more aesthetically pleasing through good Porro prism binoculars, owing to their complete lack of diffraction spikes. I came to notice this in comparing a few bigger roof prism binoculars with the 10 x 50, and in particular, a Vortex Diamondback HD 10 x 50. During daylight tests, for example, the Opticron Imagic TGA WP  10 x 50 produced crisper images with noticeably better contrast and less glare than the big Vortex roof. But that really didn’t surprise me as you’d probably have to fork out at least two or even three times more money to get a roof prism model that can compete favourably with these very well appointed Porro glasses. Under the stars though, the Diamondback HD did quite well, but didn’t quite deliver the same off-axis performance to the 10 x 50 Imagic TGA WP I compared it to. Eye relief is noticeably shorter on the big Diamondback HD too(16mm). It was also a little bit heavier(~850g) than the Opticron, which counts in extended hand-held use.

Are there better Porros out there? Yes, the Nikon SE 12 x 50 comes to mind, or a Fujinon FMT 10 x 50, or even a classic Swarovski 10 x 50,  but these cost several times more than either of these binoculars – if you can even get them. But if, like me, you can live with the smaller field of view offered by these instruments, you’re in for a real treat when you test them out in daylight or better still, under dark, starry skies where they’re in their element. Couple all this to their modest cost – both under £200 – and Opticron’s excellent 30-year warranty, and you may begin to see why it’s really hard not to like them!

Highly recommended!



Neil English has been observing the night sky for over 40 years. His latest book on binoculars will hit the shelves at the end of 2023.





De Fideli.

Product Review: The Svbony SV 202 10 x 50 ED.

The Svbony SV 202 10 x 50 ED package, courtesy of Slim Loghmari.

A Work Commenced October 20 2021

Product Name: Svbony SV202 10 x 50 ED

Place of Manufacturer: HongKong

Field of View: 106m@1000m(6.1 angular degrees)

Exit Pupil: 5mm

Eye Relief: 17mm

Dioptre Compensation: +/- 3

Close Focus: 2m advertised, 2.09m measured

Chassis: Textured rubber armoured Magnesium alloy

Coatings: Fully broadband multi-coated, dielectric and phase correction coatings applied to BAK-4 Schmidt Pechan roof prisms

ED Glass: Yes

Nitrogen Purged: Yes

Waterproof: Yes IPX7(1 metre for 30 minutes)

Weight: 951g (advertised), 914g measured

Dimensions: 16.5 x 14.8 cm

Tripod Mountable: Yes

Accessories: Tethered rubber rain guard & objective covers, lens cleaning cloth, quality logoed padded neck strap, soft padded carry case,  comprehensive instruction sheet.

Retail Price: £157-166(UK)

In ancient Hebrew lore, the number 3 is associated with harmony or completeness. How apt this is for the subject of this next review. In previous blogs I showcased two remarkable, low-cost roof prism binoculars marketed by Svbony; the SV202 8 x 32 ED and 10 x 42 ED. Despite desperate attempts to discredit these excellent performing instruments by hateful snobs and trolls, they’re now selling like hot cakes lol. But there is yet one more model in the same SV 202 series which I did not test out: enter the 10 x 50 ED

The SV 202 10 x 50 ED was kindly lent to me by Mr. Slim Loghmari, a keen binocular enthusiast and amateur astronomer hailing from North London. He purchased it directly from Svbony, Hong Kong, taking just over a week to reach him. After reading my review of the 8 x 32 ED, he went ahead and bought in all three models including the 10 x 50 ED and posted some useful video clips of its optical performance. This review will therefore complete my work on all three models from this phenomenal family of low-cost, high-performance binoculars. As you will see, the 10 x 50 ED is every bit as good as the two smaller models and really excels in some areas.


Slim despatched all of the original packaging to me so you can see that the contents are the same across the series. The package includes the binoculars in a nice padded soft case, nicely fitting, tethered ocular and objective covers, a quality neck strap, lens cleaning cloth and a comprehensive instruction manual in the major languages.

When I first prized the binocular from its case, I was immediately impressed by its excellent build quality; the same quality, in fact, as the two smaller models. The eye cups twist up and rigidly lock in place, with three intermediate positions, the focus wheel was even smoother and easier to turn than the 10 x 42 ED and the instrument felt really solid in my medium-sized hands. Like the smaller 10 x 42 ED, the focuser on the 10 x 50 ED takes about one and three quarters of a turn to go from one extreme of its focus travel to the other.

The Svbony SV 202 10 x 50 ED with eye cups fully deployed.

The dioptre ring moves very smoothly, just like its smaller siblings and stays in place once adjusted to my optimal setting. I immediately noticed the greater weight of the 10 x 50. I measured it at just 914g without the strap and lens covers. That’s actually lower than the quoted weight of 951g and rather good news if you like to handhold binoculars for prolonged periods of time.

The coatings looked identical to those on the smaller models; a deep and beautiful magenta hue as seen in daylight. These anti-reflection coatings  were applied very carefully and evenly, with no sleeks or pits.

The large oculars on the 10x 50 ED with their lovely magenta coatings.

And the objective coatings.

Unlike the two smaller models, which have just enough eye relief to use with eye glasses, the larger 10 x 50 ED has considerably more. Testing these with my own eye glasses confirmed that the entire field can be seen with ease.

The 10 x 50 ED has very comfortable eye relief for eye glass wearers.

The textured rubber armouring affords excellent protection against the elements and makes the binocular very easy to grip and hold steady. And yet it is not overly thick, like some binoculars I’ve tested over the past few years. Again, its texture and finish reminded me very much of the Zeiss Terra ED binos.

In summary, the ergonomics of the 10 x 50 ED are every bit as good as the smaller models, and has a wonderful feel about it from the second you get your hands around the barrels.

Optical Testing:

To be honest, I was expecting great things from this 10 x 50 ED based on what I experienced with the smaller models.

Did Svbony deliver?

Yes, in spades!

Performing my flashlight test on the 10 x 50 ED, showed another excellent, clean result. There was no sign of any significant internal reflections, no annoying diffraction spikes and no sign of inferior optical components causing the light to diffuse around the light source and cut down on contrast. Absolutely brilliant!

Looking at some bright sodium street lights at night showed zero problems with diffraction spikes, glare or internal reflections. ” Will make a great Moon gazing ‘scope.” I remember writing in my notebook. More on that later!

Examining the eye pupils of the 10 x 50 ED showed great results, as you can see from the images presented below. Both pupils looked nice and round, with no annoying light leaks near them. I would rate this result as excellent. Well done Svbony!

Left eye pupil

Right eye pupil

From the moment I brought the instrument to my eyes, I was treated to a wonderful, bright and sharp image, rich in contrast and saturated colours. Like the 10 x 42 ED, the instrument arrived on a rather grotty day, with light rain and leaden clouds presenting the harshest observing conditions for any binocular. I was impressed by the binocular’s control of glare, especially veiling glare – as good as I had seen on the smaller models. Even under these challenging conditions, the vibrant colours of  autumnal leaves were very striking to the eye. The wonderful light gathering power of this 10 x 50 presents a very large sweet spot, making the view especially delightful. Depth of focus was good for a binocular with these specifications and the close focus was astounding – I measured it at only 2.09m – a jolly good result. Indeed, the reader will note that the close focus on the 10 x 50 is significantly shorter than the 10 x 42 model – which came in at 2.8m in comparison. Slim already pointed that out on one of the Cloudynights threads on these binoculars, with even the premium alpha models typically coming in at 3 metres or more! This remarkable value will make the 10 x 50 an excellent choice for those who like using their binos as long distance microscopes to study insects, leaves, rocks and fungi in glorious detail. I’ve personally never heard of anyone using a 10 x 50 to do this kind of work.

Comparing the 10 x 42 ED to the 10 x 50 ED

The venerable Svbony 10 x 42 ED versus the 10x 50 ED(right).

I thought it would be useful to compare and contrast the images through the 10 x 42 and 10 x 50. After going back and forth between the instruments on a dull mid-October  afternoon, I was impressed at how consistent the image quality was. Both have very similar fields of view and both present lovely, big sweet spots. Colours are vibrant, vivid and faithful in both models. I felt the view were a little more immersive in the 10 x 50 though, a consequence I suppose of its more generous eye relief. I also felt that the image appeared slightly larger in the 10 x 50 too. Not by much but enough to notice. I suppose I could accurately determine their magnification by measuring the diameters of the objectives and the exit pupils. Dividing one by the other provides the enlargement.

If I were to be super critical, I would say that the 10 x 42 was a hair sharper than the 10 x 50 but this might easily be attributed to the smaller exit pupil on the 10 x 42, which engages a better corrected part of your eye. I noticed a small but significant increase in brightness moving from the 42mm to the 50mm bino under these dull, ambient conditions, and that larger aperture began to pull ahead as the light faded in the late afternoon. The large ocular lenses on both these models can let in some peripheral light however, but just as I found with my 10 x 42 ED, it helps to press your eyes firmly against the cups to remove it.

What is most apparent though is the weight increase in moving from the 10 x 42 ED to the 10 x 50 ED. An extra 200+ grams doesn’t sound like much of a weight hike on paper, but I felt it was quite significant in prolonged field use, moving about and negotiating fences, bushes and brambles. As a glasser who puts a maximum emphasis on portability, I would choose the 10 x 42 ED for most applications, but your mileage may vary! Indeed, I know Slim prefers the larger model because, as an eye glass wearer, he enjoys more comfortable eye relief which can make all the difference, especially when observing for prolonged periods of time.

Under the Starry Heaven

I received the 10 x 50 ED during a spell where a bright Hunter’s Moon graced the sky, drowning out the light from the faintest stars. Thus I was unable to fully test the binocular as well as I had initially intended. But I was able to confirm some excellent results just by looking at the full Moon of October 20 2021, as a rash of blustery showers moved away inland from off the Atlantic. Comparing the 10 x 50 ED to the smaller 10 x 42 ED model, I immediately noticed how much brighter it was compared with the latter. Indeed, it was almost blindingly bright in the clear and dust free sky, swept clean of particulates. Just like the 42mm model, the larger 50mm served up a beautiful, high contrast image of the lunar regolith, and once again, I came away with the distinct impression that the lunar orb was slightly larger in the 10x 50 than  in the 10 x 42. The image was free of glare and internal reflections, as my preliminary tests showed. Later, as more clouds began to move across the face of the Moon, I enjoyed some awesome light shows with the 10 x 50, with beautiful colours as the refraction of light through raindrops played out their magic, approaching and receding from the Moon. The grey maria really stood out cleanly as did several marble-white ray craters.

I detected a trace more chromatic aberration in the 10 x 50 ED compared with the 10x 42 ED model, a natural consequence of the larger glass gathering more light. But what little I did see was quite sensitive to eye placement. By taking an extra few moments to centre my pupils in the eyecups, I was able to make it all but disappear. Moving the Moon from the centre to the outer part of the field did introduce some lateral colour in both instruments but I judged this to be largely inconsequential in both instruments.  Turning next to the Pleiades, off to the east of the bright Moon, I was able to show at a glance that the 10 x 50 ED was pulling in more light as evidenced by brighter stars and more numerous stars compared with the 10 x 42 ED. Turning to the magnificent Alpha Persei Association very high in the midnight sky, I was once again bowled over by how good and sharp the fields of view presented in both binoculars. Though this stellar association is large and sprawling, filling most of the field of view in these 6-degree field instruments, I was impressed by how well they focused the stars even in the outer part of the fields near the field stops. The cluster was that little bit more impressive in the 10 x 50 ED however, a natural consequence of its greater light gathering power.

Bright white stars like Vega easily show up chromatic aberration in less well-corrected 10x binoculars in these larger formats, but on axis, both these binos delivered very clean, sharp and high contrast images with hardly a trace of false colour. Again, only by  moving the star off axis, did I see some secondary spectrum creeping in. That said, it was only slight and quite non-injurious to the aesthetics of the view, and I admit to liking a bit of the sparkly blue. Some modest bloating of the star did occur near the field stops in both instruments but I consider this edge of field distortion to be quite acceptable for general star gazing. All in all, the 10 x 50 ED will make an awesome stargazing bino, which can be enjoyed for decent long spells just hand held, but you’ll go a whole lot deeper by mounting it on a lightweight tripod or monopod.

Conclusions & Recommendations

I’ve gone on quite a journey with these wonder glasses from Svbony! I’m particularly impressed by the two larger glasses though; they have phenomenal optics that will delight even the most discriminating of observers, especially when you factor in their modest cost. To be frank, they are worth many times more than what Slim and I paid for them. But that’s life; sometimes fortune smiles your way. I give these instruments my highest recommendation. Like I said before, my 10 x 42 ED has sated any desires I once cultivated to acquire an alpha model in this size category from the leading European binocular manufacturers. Let’s just say I’d rather spend my spare cash on other things! Their optical performance leaves little to be desired! Go grab yourself a bargain while you can!

Thanks for reading.


The author would like to sincerely thank Slim Loghmari for kindly sending the SV202 10 x 50 ED for review. Rest assured, it will be winging its way back to its proud owner in the week ahead.

De Fideli. 

Product Review: Pentax SP 10 x 50 WP.

The Pentax SP 10 x 50 WP package.

A Work Commenced July 7 2021




Product: Ricoh-Pentax SP 10 x 50 WP 

Country of Manufacture: China

Field of View: 87m@1000m( 5 angular degrees)

Eye Relief: 20mm

Close Focus: 5.5m

Exit Pupil: 5mm

Focuser: Central, lockable

Chassis Material: Aluminium with rubberised overcoat

Coatings: Fully broadband multi-coated throughout

Dioptre Range: +/- 4 dioptres

Nitrogen Purged: Yes

Waterproof: Yes (JIS Class 6)

ED Glass: No

Weight: 1060g

Dimensions: 18 x 18 cm

Retail Price: £170UK

Supplied with: Soft carry case, logoed carry strap, plastic objective and ocular covers, multi-language instruction sheet.


Pentax is a company long synonymous with good optical quality. Over the last few years, I’ve reviewed a few models manufactured by this company, ranging from the very small(6.5x 21) to the very large(20x 60). In particular, I’ve included an earlier incarnation of the  20 x 60 SP model in my own personal arsenal of binoculars, where it’s employed in deep sky observation and regular white light solar observing. So, I was excited to see how its smaller sibling, the 10x 50 SP WP, would shape up in field tests.

First Impressions

I purchased the binocular with my own money and it set me back £170, inclusive of delivery charges. The binocular arrived double boxed, including the instrument itself, packed inside its soft case, together with plastic end caps for both the ocular and objective lenses, a logoed padded next strap and instruction sheet containing information concerning the warranty. The plastic caps that protect the optics of the 10 x 50 SP looked identical to those that accompanied my 20 x 60, and together with the woefully inadequate soft case, represent the weakest links in the entire package. The caps are loosely fitting and invariably fall off  when the binocular is picked up. As for the case, it does very little to protect the binocular from serious knocks so should really be upgraded to either a padded soft case or better still, an aluminium hard case to protect your investment.


Thankfully, my initial impressions of the binocular itself were far more favourable. When I unpacked it, I was immediately struck by its rugged build quality. The binocular weighs in at a hefty 1kg and is covered with a thick layer of synthetic rubber identical to that found on my 20 x 60 . Like its bigger brother, it has a lockable focuser; simply push the wheel forward and it disengages with the internal gearing, preventing the wheel from being moved. Although not an essential feature by any means, I can see where it would come in useful if one observes targets at a fixed distance from the user or when observing the night sky, where all the subjects are located more or less at infinity.

The central focus wheel is very easy to grip and is lockable simply by pushing it forward.

The twist up eyecups are very well made and very comfortable to use. There are three positions; fully down, intermediate and fully extended. Eye relief is a very generous 20mm. Usually, I observe with the eye cups fully extended but I actually found the view to be most comfortable and immersive at the intermediate position without wearing eye glasses.

The very solid twist up eye cups are comfortable to use and have three positions. Eye relief is generous allowing those who wear glasses to fully engage with the entire field.

The ‘WP’ part of its name, I assume, refers to ‘Water Proof,’ with a specified JIS class 6 rating. The instrument is purged with dry nitrogen gas to prevent internal fogging and is O-ring sealed. The dioptre ring is located under the right ocular lens and is negotiated by moving an easy to access lever which can be adjusted clockwise or anti-clockwise. It is reasonably stiff to the touch so should hold its position well. The underside of the 10x 50 SP WP has two large thumb indents for easier hand holding. I found that my thumbs naturally rested in them while holding the binocular up to my eyes.

The focus wheel is very stiff; a strict no-no for birding or any activity that requires rapid focus changes. But for stargazing or for stationary targets located in the distance, it works just fine.

You’ll find two large thumb rests on the underbelly of the binocular for more secure gripping.


The proof of the pudding, of course, lies in the eating, and this is where this well-made classic Porro prism binocular really shines. The SP series underwent an upgrade from the first generation models, with better multi-layer anti-reflection coatings being applied throughout the optical train. Allbinos tested this model out and measured a light transmission value of about 85%, which is very good indeed considering the modest price tag on this binocular, as well as the fact that some of the world’s best Porro prism binos achieve about 95% or so.

Not for the Birds

Inspecting the innards of the instrument in broad daylight showed it to be clean and dust free. Setting up my iphone torch to its highest setting in my back garden at dusk and placing it a comfortable distance away revealed a few minor internal reflections and no diffraction spikes or diffused areas; another good result indicating that all was well with the instrument in keeping bright light sources under control. Placing the beam just outside the field of view showed very little ghosting so this will be a good binocular to observe bright objects in the night sky such as the full Moon and stars located near it. It will also garner excellent views of cityscapes at night. Close focus was measured to be about 5.3 metres – a little better than advertised but nothing to write home about. The coatings on the ocular and objective lenses seem to be very evenly applied. In addition, the objective lenses are very deeply recessed which helps protect the optics from the vagaries of the British climate and also cuts down on stray light.

Very evenly applied multi-layer anti-reflection coatings applied to the objectives help transmit a decent amount of light through the optical train.

In broad daylight, the view through the Pentax 10x 50 SP WP is very impressive, with great contrast, good colour rendition and good but not outstanding control of glare. Depth of focus is not bad, but the 3D pop that Porro prism binoculars are famous for was there in spades. Colour correction is excellent, even off axis, where one can detect a small amount of lateral colour. Field curvature is very gentle but does show a fairly minimal amount of pincushion distortion near the field stops. Even though the field of view is fairly narrow at 5 angular degrees, it didn’t feel overly restrictive to my eyes. At just over 1kg weight and delivering a 10x optical boost, these are not binoculars that one could handhold for long but it’s certainly possible to scan the landscape and night sky for a few minutes before some fatigue sets in. These are however, perfect for use on a lightweight monopod or tripod for ultra stable viewing.

Further testing at dusk showed excellent control of internal reflections and clean, crisp images garnered from a bright sodium street lamp. Placing the lamp just outside the field of view showed up no significant off-axis flares. Placing the binocular on a light weight monopod and turning them on the night sky also served up excellent results. Centring the bright Summer luminary, Vega, in the binocular field and focusing in showed a pinpoint sharp image with no secondary spectrum and with no diffraction spikes. Better still, moving the star to the edge of the field induced only a little distortion and some lateral colour(purple fringing), indicating that the aspherical optical element built into the eyepieces of the Pentax SP binocular were doing their jobs well. And while the skies were far too bright to provide a more in-depth study, with strong Summer twilight upon us here in central Scotland,  I compared and contrasted the view through the Pentax 10 x 50 and my trusty Barr & Stroud Series 5 8 x 42 mounted on a second monopod. Turning my attention to the well placed Coathanger asterism in Vulpecula revealed a cleanly resolved view in both instruments, but with fainter stars showing up better in the Pentax, albeit in a smaller true field.

Conclusions & Recommendations

In recent years, thanks to great advances in technology, there has been a steady movement within the amateur community towards roof prism designs over older, Porro prism binoculars. But after spending a few weeks testing out this affordable model from Pentax, I was genuinely surprised and delighted by its optical performance. Indeed, you’d have to fork much more money for a roof prism binocular with the same specifications as this Pentax to get the same optical quality. The only real advantage of the roof prism incarnations at 10 x 50 are their lower mass(but not by much) and slightly smaller frames. Having sampled a few inexpensive and mid-priced 10 x 50 roof prism binoculars in the past, I can say hand on heart, that they did not deliver the light transmission values anywhere near those attained by this classic, affordable 10 x 50. Indeed, I would strongly recommend readers to look more closely at tried and trusted Porro prism designs in aperture classes of 50mm or above over the roof prism varieties, especially now that they come with full waterproofing.

Qui bono?

Amateur astronomers looking for quality deep sky views on dark, clear nights, and casual daytime viewers with permanently set-up tripods or monopods surveying targets set in the distance. Remember that five degrees is still plenty good enough for the vast majority of deep sky observing! These would work very well in holiday cottages set by a lake or overlooking a picturesque valley floor. And although they can be handheld for short excursions, they do benefit greatly from mounting.

Very highly recommended!




Dr Neil English has over 40 years experience studying the night sky with all sorts of telescopes, but in the last few years has devoted himself to seeking out bargains for savvy binocular enthusiasts. His highly lauded 650+ page magnum opus, Chronicling the Golden Age of Astronomy, summarises four centuries of telescopic observing, from Thomas Harriot to Patrick Moore.



De Fideli.

Product Review: The Pentax PCF WP II 20 x 60 Binocular.

Grandes Binoculares.

The achromatic telescope has enjoyed a long and illustrious career in the hands of skilled observers. In my most recent book, Chronicling the Golden Age of Astronomy, I have documented and shared with you the amazing achievements of the classical refractor over three centuries of time. But it would be quite inaccurate to claim that it has been really superceded by anything else in the modern age. This is especially true in the case of binocular manufacture, where sales of achromatic instruments vastly outsell models which possess modern ED glass. And there’s a good reason for this: ED is an expedient luxury that impacts little to the binocular view, what with their low magnifications and wide fields. For every ED model offered, there are a great deal more made with traditional crown & flint, and that is true even for some premium brands.

Consumers vote with their wallets.

We still live in the achromatic age.

Having enjoyed and appreciated the achromatic refractor for decades, I have come to the conclusion that it is in the binocular that achromatic optics has reached its zenith. Properly made, achromatic optics provide wonderful, sharp and contrasty images of the eartly and heavenly creation. This conclusion has been reached by extensive field experience of a variety of achromatic binoculars that show vanishingly small amounts of secondary spectrum and which are far more alike than different to models with ED glass, but at a fraction of their cost. These sentiments are also reflected in the models still being marketed by some big names in the large binocular world, including Celestron, Fujinon and Oberwerk. What these manufacturers offer is great performance at prices that won’t leave you out in the cold.

For certain kinds of visual astronomy, large binoculars simply can’t be beaten. The ability to use two eyes rather than one greatly influences the quality of the views, where it impacts depth of field perception, faint object detection and significant improvements in perceived contrast. Without a shadow of doubt, large binoculars are the single most powerful way to enjoy larger deep sky objects, where telescopes simply cannot offer the same ‘zoomed out views.’ That said, it’s very much a Goldilocks scenario; increase the magnification too much and you lose those gorgeous panoramic sights, but when the power is too low, finer and fainter details remain elusive. It was with this realisation that I took a punt on a curious large achromatic binocular made by Pentax; enter the PCF WP II 20 x 60.

That Pentax were prepared to put their name on the PCF WP II 20 x 60 is a lesson in objectivity. Why would such a prestigious manufacturer of high-end cameras and sports optics decide on a well-appointed, large achromatic binocular? The answer is that when well made, even a 20x model would deliver up wonderful, tack sharp views of the landscape by day and breathtaking celestial vistas by night. And this has been achieved at a price point that suits the budgets of discriminating amateur astronomers who just appreciate well designed classical optics; true observers rather than casual sightseers; folk who want real substance rather than the latest ‘gee whiz’ gimmicks.

                                             A Full Featured Binocular

Though the instrument can be acquired at a good, price new (£219 UK for the latest SP model), I was lucky enough to acquire this binocular in excellent, used condition for a little over half the retail price. The former owner had taken very good care of it, added a sturdy carrying strap and dispensed with the flimsy carrying case, replacing it with a sturdy foam-lined aluminium case.

The Pentax 20 x 60 snug in its foam-lined aluminium case. Note the tripod adapter attached to the instrument.

The porro prism binocular weighs just 1.4 kilos (~3 pounds), surprisingly light for an instrument of these specifications and is water and splash proof. This may account for the WP(water proof?) in their name. The interior is purged with dry nitrogen gas to prevent internal fogging and to minimise corrosion. The body, which is constructed of a lightweight magnesium alloy, is covered with a protective rubberised substrate that is easy to grip and is tough and durable in all weathers.

The Pentax 10 x 60 is dsisgned for rough weather use.

The optics are fully multi-coated to maximise light transmission to the eye and reducing contrast-robbing internal reflections to a minimum.

The beautifully applied multicoatings on the large 60mm objective lenses.
Hard coatings on the ocular lenses maximise their durability.

The centre focusing wheel is remarkable in two respects. Firstly, it is quite tight in comparison to other binoculars I’ve used. This was intentionally done by the manufacturer, as you’re not likely to use this instrument watching fast moving birds or some such, necessitating the rapid change of focus position. This increased tension does however allow for very precise focusing to be achieved. Secondly, there is a facility on the focuser to lock it in place. Simply push the focusing wheel forward and it is locked in; a nice design feature that can be advantageous. For example, if you end a session with the binocular focused on the stars at infinity, locking the focuser in place ensures that you can re-engage with the sky whenever you’re next out, with minimal (if any) re-focusing necessary.

The well designed focuser ensures very accurate focusing of the instrument and can be locked in place simply by pushing the focussing wheel forward, as indicated.

The strong bridge connecting both barrels of the binocular is reassuringly stiff, allowing one to easily obtain the correct inter-pupillary distance (IPD) and only requires occasional adjustment in field use.The dioptre setting is found under the right-hand eyecup allowing independent focusing of both barrels. It has just the right amount of tension and stays in place without any fuss.

The dioptre setting on the binocular lies directly under the right eye cup.

I really like the twist up eyecups on the Pentax PCF WP II 20 x 60. Like my smaller roof prism binoculars, they click into place and are quite secure. Eye glass wearers just need to hold the eyecups down, while those who don’t (yours truly included) can extend them upwards for very comfortable, full-field viewing. The texture of the cup is hard rubber which is a far cry from the cheap fold up/down eyecups seen on many other large binoculars in this price range. Indeed it is my experience that the latter can fragment in prolonged field use, necessitating their replacement from time to time. These sit very comfortably against the eyes and never need to be adjusted. Eye relief is exceptional; a very comfortable 21mm.

High quality hard rubber eye cups twist up and lock in place for non eye glass wearers. Those who wear eye glasses will likely keep them fully down while in use.

                                                    Mounting Options

It is not the weight per se that forces one to mount this binocular. As stated above, they are quite light for their optical specification. Rather, it is the 20x magnification that limits their hand-held use. That said, I can hold them reasonably steady by extending my hands a little further forward on the barrels than with my smaller binoculars and this strategy can work quite well for short, ‘quick peek’ sessions. Incidentally, I discovered thumb indentations on the belly of the instrument presumably designed to assist hand holding! Golly gosh!

Ain’t that sweet: indentations to fit the hand on these big binos!

Still, whatever jitter you have, it will be magnified 20 times while looking through it. Such high powered binos definitely require some kind of stablising action and, in this capacity, one can either elect to use them tripod-mounted or by using a monopod.

A word of caution; avoid using those cheap plastic tripod adapters that often attend bargain basement large binos such as the ubiquitous 15 x 70. These introduce an annoying level of flexure that will almost certainly detract from enjoying the instrument in the field. It is strongly advisable to invest that little bit more in a good quality, all-metal unit sold by Opticron and other companies. Indeed, I found the same adapter that fits my 10 x 50 roof prism  binocular also work swimmingly well with this larger instrument.

Tripods have their pros and cons though. Although they offer the maximum level of stability and have built in slow-motion controls on both axes, they are quite uncomfortable to use when aimed high in the sky. I found it quite hard to find a suitably comfortable positioning of my eyes when used in the seated position. That said, a trpod was useful in checking collimation of the barrels and certain daylight activities, but in the end the most suitable way I’ve found to use this instrument is by mounting it on a simple monopod.

Using a high quality(solid aluminium) ball & socket adapter, mounting the 20 x 60 on a monopod is quick and easy to execute.

Travelling light; the author’s preferred mode of mounting the Pentax 20 x 6o binocular using a light but strong extendable monopod and ball and socket head.
Simplicity itself; the 20 x 60 mounted on a lightweight but sturdy monopod.

Using the monopod, I have been able to get very stable views during daylight and extended periods of night use. For quick looks, I usually stand and adjust the angle of either the monopod itself or the ball & socket head. For the most stable viewing sessions however, I relax in a recliner and, securing the monopod base between my feet, have attained nearly jitter-free viewing. I have learned to place some of the weight of the binocular on my face, which increases the overall stability to a significant degree.

Yours truly suitably attired, demonstrating the use of the monopod.

Pentax PCF WP II 20 x 60 Optics

As the size of binoculars increase, it makes a lot of sense to decide on a porro prism design, rather than its roof prism counterpart. Porros are less expensive and just easier to make well and also offer slightly more light throughput than their roof prism counterparts. The optics of the Pentax PCF WP II 20 x 60 are notable. All lenses are fully multi-coated with a protective overcoat. The Bak-4 prisms are also multi-coated. The oculars are constructed from aspherical lenses which offer several advantages over conventional lens systems, espcially in the suppression of spherical aberration and a number of off-axis aberrations that plague conventional porro binos. In addition, fewer elements are needed with ashperical designs, significantly reducing weight.  Rather than rambling on with this, it’s best to hear it from an established optics firm. Here is a link to more information on aspherical lenses.

Collimation test

Collimation of binoculars is important especially on these high power units. One quick way to test for collimation is to mount the binocular on a tripod and select a target at least a kilometre away. I elected to use the snow capped Fintry Hills a couple of miles distant.  With the correct IPD selected for my eyes, I look through the binocular and slowly pull my eyes away until the exit pupils start to become separated and I can only see the top of the field. If there is miscollimation, one image will be raised slightly higher than the other. To my relief both images remained perfectly level. Testing for sideways collimation involves aiming at a distant target and testing to see if images at the edge of the field are precisely aligned on both sides. In doing this, I detected a very slight misplacement but it was so small that I wasn’t worried. The images merge very easily and you don’t encounter eye strain even after prolonged use.

Misaligned prisms can also be revealed by examining the shape and size of the exit pupil when the binocular is pointed at a source of light. As you can see below, both exit pupils are round and of the same size indicating that all was well.

Two round exit pupils of the same size indicate good alignment of the prisms with no picking off evident.

Daytime tests:

The binocular has a 3mm exit pupil. This ensures the best part of your eye is imaging the field. And oh what a field! When precisely focused images of daytime targets are bright and tack sharp across nearly the entre field (read 95%), indicating that that aspherical optics were working well. Contrast is excellent with very effective baffling of stray light. On axis, very little chromatic aberration could be detected but I could see that off axis some lateral colour was evident. That said, it was very slight and totally acceptable to my eye. In comparison to a side by side test made with my ShortTube 80 f/5 achromatic telescope charged with a power of 16x (5mm exit pupil) in a wider 3.75 degree field showed much higher levels of lateral colour.

Spying on a corbie perched on a TV aerial against a bright sky background about 40 yards in the distance showed very slight secondary spectrum around the crow’s jet black plumage. I deemed the result quite excellent and non-intrusive for an achromatic binocular of these specifications.

Close focus was estimated to be about 8.5 metres.

A Curious Aside: More on ED glass in binoculars here  and here. 

Nightime tets:

For nightime testing, I mounted the 20 x 60 on a simple monopod, as described previously. This is a very quick and effective way to get going with this large binocular. Some users of the instrument complained about the small field of view offered by the Pentax PCF, what with its 2.2 degree true field. Others commented on the sensitivity of the instrument to eye placement, but truth be told, I found neither of these things to be in the least bit distracting. You see, I’m used to very small fields working with close double stars at very high magnifications and with fields that are far smaller than what is offered by this big gun. Right off the bat, I was enjoying very comfortable, stable images. A 2.2 degree field is small as 60mm binoculars go, but it is plenty good enough to frame larger deep sky objects. To my mind, it simply boils down to training.

My first light target was the Pleiades cluster in Taurus. Getting myself comfortably positioned on my recliner and adjusting the monopod, I was absolutely blown away by the sight of this magnificent open cluster in the 20 x 60! More like an astrophoto than anything else, the entire cluster was beautifully framed, crammed full of gorgeous blue-white starlight and razor sharp from edge to edge. The sky hinterland was jet black with none of the flaring of stellar images that I had experienced in my brief rendevous with budget 15 x 70 models.  It is immediately apparent that the field is very flat from edge to edge, with no distortions that I could register. It just exuded quality! And although I own a number of good telescopes that can collect far more light than this 20 x 60 instrument, they could not beat it in terms of delivering such a magisterial image. Focusing the binocular was particularly satisfying; very small motions can make the difference between seeing the faintest stars and not seeing them at all.

Turning next to the Sword Handle in Orion, which is also perfectly framed in the 2.2 degree field,  I was deeply impressed at the wonderful contrast and colour rendering of the bright O/B stars in the field; tiny little pinpoints of light bathing my retinas. I could easily make out the greenish hue of the great Nebula in Orion (M42) and a steady hand revealed at least two of the tiny quartet of stars comprising the famous Trapezium (Theta Orionis complex).

Though the field of view is not large enough to frame the three bright Orion belt stars, the 20 x 60 pulls out many more faint stars in Collinder 70 that are quite beyond the reach of my regular astro binocular; my trusty 10 x 50. Suddenly, this preternaturally lovely open cluster has become a whole lot more crowded!

In the wee small hours of freezing January nights, I would watch the sky, waiting for the Beehive Cluster (M44) in Cancer to approach the meridian. Having experienced the Pleiades, I was very much looking forward to seeing this large and sprawling open cluster in the 20 x 60. And again, it did not disappoint; the view was enthralling! The entire field was filled with pinpoint stars against a jet black sky. Using two eyes greatly enhances the view and there is a lot to be said for seeing these wonders of God’s creation in their correct orientation, as if they were made for such instruments.

The glories of the Double Cluster in Perseus were a joy to behold in this high power binocular; great mounds of starlight of varying hues with curious fans and spirals of distant suns meandering their way from their crowded centres. Compared with a 10 x 50, the view was simply in a different league!

I didn’t notice much in the way of chromatic aberration in the images, save for a brief spell with the Dog Star, Sirius. It’s brilliant light is dazzling in the 20 x 60, coruscating with various colours from moment to moment. In my opinion, secondary spectrum is a complete non-issue with this instrument for astronomical use; just set it up and go stargazing!

Although smaller deep sky objects are best examined in telescopes with more light gathering power and their ability to take higher magnifications, I nonetheless enjoyed some very pleasing views of the Auriga trio of Messier open clusters; M36, M38 and especially the sumptuously rich M37, which appears satisfyingly large, well defined and glistening with the light of many faint suns. M35 was also big and prominent in this large binocular with dozens of its constituent stars being easily made out.

This is a wonderful instrument for framing and observing the Engagement Ring: a circular arrangement of faint stars encrusted with the creamy bright Polaris as the principal gemstone. Smaller, more conventional binoculars really don’t show this structure half as well, owing to their lower power, wider fields and reduced light grasp.

With such a large and powerful binocular, the colours of stars really stand out; marmalade orange Propus, sanguine red Mu Cephei, the soft yellow pastels of Capella and the Orion belt stars, white as the driven snow. This instrument would also make a dedicated variable star observer very happy, what with its impressive light gathering power (reaching down to perhaps + 11 magnitude from a dark site with good transparency) in a very well corrected, wide field. The 20 x 60 might not be the first instrument that comes to mind for a budding comet hunter, but I am reminded of the advice of the great 19th century observer, William F. Denning, who recommended an instrument with a field of view of between 1 and 1.5 degrees for such work. And in more modern times, the distinguished comet discoverer, David H. Levy, advises that the comet-seeking instrument deliver a field of just 0.75 angular degrees! Seen in this light, the suggestion doesn’t seem quite so far fetched.

The telescope provides wonderful views of some prominent binocular doubles; Mizar & Alcor, o1 Cygni, Albireo, Mintaka and Cor Caroli, to name but a few.

Structure within Structures

The Pentax PCF 20 x 60 is a formidable instrument for delineating structures within larger asterisms. Just have a look at the stars around fiery red Aldebaran with this bazuka! Sure, you can’t see the entire Hyades but with its pinpoint stars, wonderful contrast and generous ‘space penetrating power’, as Sir William Herschel of old liked to say,  it allows you to capture painfully beautiful star fields, rich in light and colour against a velvet black sky.  It’s even more amazing when pointed at Alpha Persei; the field is littered with lovely stellar jewels sparkling through the cold dark of interstellar space. This will be a great instrument to begin a study of stellar hinterlands around the brightest stars in general, something I thought about in the past but never pursued because of other diversions. I think it’s tailor made for such projects!

Ready to go when you are: the Pentax PCF 20 x 60 can be used at a moment’s notice between heavy showers when some clear spells manifest.

Starting in Gemini and running the binocular haphazardly across the sky through Auriga, northern Orion, Taurus, Perseus and ending in the gloriously rich Cassiopeia, the binocular shows me many new asterisms which I had not witnessed before, a consequence of its unique field of view, magnification and image orientation. Almost every field stumbled upon brings new bounties, delicate arrangements of stars unnoticed in smaller binoculars; vast shoals of starlight in the open ocean of space.

Moon Watching:

In the early days of February 2019, I got several opportunities to observe the waxing crescent Moon through the monopod-mounted Pentax PCF 20 x 60 binocular. The views were amazing; razor sharp, beautiful contrast, most excellent suppression of internal reflections that can easily plague lesser binoculars. Indeed, I’ve devised this simple but highly discriminating test as a way to quickly establish whether a binocular is fit for general astronomy use. If the unit shows flare and/or internal reflections when pointed at the Moon, it’s leaking light.

The image scale of the Moon seemed larger than I expected it to be in going from a standard 10x binocular to this 20x unit. It just seemed like I was getting a higher power than the 20x marked on the Pentax binocular tube. This is no doubt an illusion, a consequence I suppose of the Moon’s taking up a larger fraction of the area of the field than seen in my trusty 10 x 50 binocular.

The earthshine from the dark side of the Moon was very prominent and as the crescent continued to grow, the binocular revealed more and more details of the lunar regolith. The image scale is great for seeing high resolution details of the battered southern Highlands. On the evening of February 10, I enjoyed a wonderful view of the three large craters; Theophilus, Cyrillus and Catharina on the eastern shore of Mare Nectaris. Up north, Atlas and Hercules could be clearly made out with a steady hand. The limb displayed a sliver of colour; sometimes green, sometimes yellow, depending on where my eyes were postioned.I judged the chromatic aberration on this tough target to be minimal and completely non-intrusive to a seasoned telescopic observer. Contrast between the bright lava fields and darker maria was very well presented, producing an extremely immersive, aesthetically pleasing view.  This will be a great binocular to observe the early waxing Moon during March and April, when earthshine is at its most prominent and I look forward to fielding the instrument for this purpose. Sure, the binocular cannot substitute for the telescope proper, but it certainly complements those high-power, high-resolution views. The big binocular has a charm all of its own and should really be enjoyed on its own terms.

Concluding Remarks:

A quality, large binocular at a great price!

As you can probably discern from the above write up, I took to this instrument like a proverbial duck to water!

The Pentax PCF 20 x 60 WP II  is an impressive performing, large binocular, with a rugged but durable housing. It is water and splash proof, making it suitable for routine and/or prolonged work by day or by night. Its high magnification requires a stable mounting system to get the best out of the instrument.The ability to lock the focus in place is a useful mechanical feature that will be greatly appreciated by all those who use it in the field.

The Pentax 20 x 60 has very high quality optics, including properly collimated porro prisms and quality multi-layer coatings that efficiently transmit light to the eye. All lenses are also fully multicoated. The aspherical optics deliver a very highly corrected field, from edge to edge. Chromatic aberration is very well controlled and is not intrusive in normal use. Contrast-robbing internal reflections are also very well suppressed in this instrument. The binocular is very easy to use and has comfortable eye relief(21mm with the twist-up eyecups), allowing hassle-free viewing for both non eye-glass wearers and those that like to observe with their glasses on.

Less experienced observers have complained that the binocular has too small a field, but I am reminded of the superbly designed (but very expensive!) Takahashi Astronomer 22 x 60 binocular which sported a field of view of just 2.1 angular degrees, so slightly smaller than that offered up by the Pentax 20 x 60! In truth, a 2.2 degree true field is perfectly adequate to frame the vast majority of celestial objects.

The binocular is ideally suited to framing showpiece deep sky objects for careful study, such as the Double Cluster, the Pleiades, the Beehive Cluster and other large Messier objects, but is also well appointed for use in comet hunting/observing and variable star work. Its high magnification and excellent contrast produces magnificent views of the Moon that will impress anyone who uses it.

The Pentax PCF 20 x 60 WP II can also be employed as a two-eyed spotting ‘scope in long-distance daylight viewing/surveillance, e.g. observing a bird’s nest at a comfortable distance or in a variety of maritime applications.

Its very reasonable retail price makes this a most attractive instrument for budget conscious amateurs who do not want to compromise on optical performance.

Highly recommended!

Post Scriptum: Stephen Tonkin, an accomplished binocular astronomer and author has written another review of this binocular (the newer SP incarnation). It can be viewed here.

Neil English is the author of several books on amateur astronomy. His latest work, Chronicling the Golden Age of Astronomy, is now availlable in hardback and electronic formats.

De Fideli.

Product Review: The Barr & Stroud Sierra 10×50 Roof Prism Binocular.

The Barr & Stroud Sierra 10 x 50 binocular with peripheral eyeshields.


There has never been a better time for the binocular enthusiast. Nowadays, a huge range of models are available that offer high quality optics for nature studies, birding and astronomy. Doubtless, this revolution is wrought by advances in technology; better glass, better coatings,  as well as steady progress in materials science. Greater competition among the various optics houses also helps drive prices down, so that many more people can take advantage of this new technological wave; and that is good news for a multitude of hobbyists.

I recently described my very favourable impressions of a new instrument; the Barr & Stroud Sierra 8 x 42 roof prism binocular, which offers excellent optics, good weather proofing, great compactness and very light weight compared with my old, well-worn 7 x 50 porro-prism binocular, which had served me well for three decades. The 8 x 42 is an ideal instrument for daytime applications, where its decent light gathering power and efficient transmission of light to the eye, yields images that have great colour fidelity and excellent contrast. As I also explained, the 8 x 42 can be used productively for night-time applications, where it offers good performance within the remit of its aperture.

Still, as good as the 8 x 42 is, I felt I was missing out a little were I to use the instrument for specialised deep sky viewing, compared with slightly larger instruments that have long been the staple of the binocular astronomy enthusiast; I wanted to be able to do binocular astronomy using only a binocular; under its own terms.

Enter the venerable  10 x 50. And that prompted me to seek out a high quality instrument that I could almost exclusively dedicate to night sky use. A good 10 x 50 would gain about about a half a visual magnitude over the 8 x 42 and its slightly higher magnification would be advantageous for pulling out faint deep sky objects that are not so well seen with the smaller binocular.  I had heard some great things about the Nikon Aculon 10 x 50 porro prism binocular and I seriously thought about acquiring it, since it seemed to offer a lot of bang for the buck, but when I considered its weight- 898g, it seemed rather on the heavy side. You see for me, weight is a brute fact: the heavier the binocular, the less I would likely use it.

Deeply impressed by the way the compact 8 x 42 handled various situations, I looked again for a roof prism model offering 10 x 50 specifications and it wasn’t long before my interest was piqued by the Barr & Stroud Sierra 10 x 50 roof prism binocular, which I felt was very reasonably priced. So I took the plunge and ordered one up.

Just like the 8 x 42, the 10 x 50 Sierra arrived very well packaged in an attractive box. The same soft, black carry case housed the binocular, as well as receiving the neat 10-year warranty card and single page instruction sheet.

The 10 x50 Sierra binocular in its soft carry case.


The binocular is very well built, with a strong, rigid bridge that is not easily moved once the proper interpupillary distance was set. Ditto for the diopter setting, which is quite stiff and thus not likely to budge in field use. Like the 8 x 42, the unit is o-ring sealed and purged with dry nitrogen gas making it fog and weatherproof (water resistant up to 1.5m for three minutes), Its weight is considerably lower than the Aculon; just 780g. The focuser is smooth and firm to the touch and offers an excellent close focus distance of just 2.5 metres (tested). It also has rubberised caps to protect both the objective lenses and the eyepieces. What’s more, they can be permanently affixed to the binocular so they won’t get lost in a hurry.

The 10 x 50 Sierra is fully multi-coated and the prisms are phase coated for optimum field performance.


Like the  8 x 42 Sierra, the 10 x 50 unit features fully multi-coated optics and the BaK-4 roof prisms are phase coated to maximise image brightness, contrast and colour fidelity.

Very nicely designed oculars ensure comfortable viewing, either with or without eye glasses. Note; the oculars are shown fitted with eyeshield peripheral shades (purchased separately).

The eyecups can be twisted upwards for use without eyeglasses, or can be kept fully down if oe decides to use them with eyeglasses.

Eye relief is very generous 17.8mm and the field of view offered is just under 6 angular degrees.

Full details of the 10 x 50 Sierra can be viewed here.

The very same afternoon the 10 x 50 Sierra arrived, I took off on my long country walk to see how they performed during daylight hours. The first thing I noticed was their additional weight; fully 130g heavier than the 8 x 42 Sierra. After a few miles of walking with the instrument hanging around my neck, I experienced significantly greater back strain than I was accustomed to carrying the lighter 8 x 42. This was fully expected however and affirmed my conviction that 8 x 42 would better serve me during daylight hours.

I fully expected a little more chromatic aberration, given the specifications of the 10 x 50 and this was confirmed by focusing on a distant hilltop against a bright overcast sky. Still, it was very minimal and perfectly acceptable. Certainly, it would never be enough for me to consider a model with ED glass; that would be overkill to say the least! The images served up by the 10 x 50 were beautiful, crisp and bright, with great colour fidelity and excellent contrast, although it was immediately acknowledged that I would be sacrificing some field of view over the 8 x 42.

While using the 8 x 42 for prolonged periods during my daily walks, I noticed that on bright days, light entering my peripheral vision was causing some annoying glare to seep in. This had nothing to do with the type or make of binocular but merely reflected an operational issue while using any binocular. Thankfully, I found a great solution; enter Eyeshields produced by a US-based company called Field Optics Research.

A good product for any binocular user. Eyeshields by Field Optics Research.


Costing £25 delivered, I received two pairs (one for the 8 x 42 and the other for the 10 x 50) of eyeshields which fit snugly onto the oculars and can be deployed at a moment’s notice. They remain permanently affixed to the eyepieces and fold down when not in use. Another neat feature of the EyeShields is that you can still use the rubberised dust caps with them on. They do a simple job, shileding your peripheral vision from stray light, but also stop wind-driven dust from accumulating on the oculars. They work really well, effectively eliminating the said glare I was encountering during my observations. Though a bit costly for what they really are- rubber eyeshields in a tin box lol –  I can certainly vouch for their effectiveness and would highly recommend them to any binocular enthusiast.

One thing caught my attention though: I noticed that the company state that the product is “patent pending”. I don’t know if something like this can really be patented though. I mean, I have similar eyeshields which came with some of my older orthoscopic and Plossl eyepieces, so it’s hardly something truly novel.

The eyeshields very effectively block peripheral light entering the eye while using binoculars in bright ambient light settings.

Ad Astra

Though I acquired the binocular at the start of November 2018, I was not able to conduct star tests until the evening of November 7, owing to a prolonged bout of cloudy, damp and misty weather, typical for this time of year, which all but extinguished the light from the stars. Seeing some breaks in the clouds after dark stoked deep feelings of joy, and I immediately grabbed the 10 x 50 to begin my observations. My first impressions were very favourable. This cost-effective instrument served up beautiful views of the Pleaides, my first target in northern Taurus. I immediately appreciated the wonderful contrast of the instrument and could instantly make out many more fainter members than I could see with the 8 x 42. The increased image scale was quite significant too, framing the asterism very well in the field of view.

Two tests of the size of the field were conducted; first with the Hyades, which was quite simply stunning in the 10 x 50 and I was delighted to see that the main ‘V’ shaped configuration was nicely framed in the binocular field with a little room to spare. The field came alive with many sparkling jewels, brighter and more numerous than in the 8 x 42. Star colours seemed even more vivid too.  Since the main part of the Hyades is in excess of 5 angular degrees wide, this comported well with the field quoted in the specifications table.

In the second test, I was able to get brilliant white Rigel just inside the same field as the Orion Nebula (M42), a distance I estimated to be about 5.7 angular degrees, so quite close to what the manufacturer claimed. It’s nice when the stated specifications agree with experience!

At tightest focus, brilliant yellow Capella in Auriga showed no fringing of any sort that my average eyes could detect, and moving the brilliant autumn luminary to the edge of the field showed that it remained agreeably sharp and tight; perhaps even a tad better than the wider field offered up by the smaller 8 x 42. I reasoned that this was not to be unexpected, as it is easier to get a better corrected field as the field shrinks in size.

Sweeping the binocular through the heart of Auriga showed its clear superiority over the 8 x 42. The 3 Messier open clusters were easier to pull out from the background sky and I was also able to more easily see a number of other fainter nebulae that were mere suggestions in the smaller Sierra binocular.

As a resolution test, I steadied the binocular on the side wall of my house and aimed it at golden Albireo, now rather low in the northwestern sky. I believe I was just able to pick off its companion, something I have not been able to achieve using the 8 x 42 after several attempts.

The weight difference between the Sierra binoculars is immediately obvious under the painted canopy of the night sky. It is harder to hold the 10 x 50 steady, but I find that this is less important for large deep sky objects than it is for studying smaller targets like individual stars, where the wondrous creation of the human eye-brain seems to act as a natural image stabiliser. I found it beneficial to move my hands further forward in order to get a better grip of the objective end of the instrument while in field use. This strategy definitely helps me to get the most stable images from the 10 x 50 during prolonged (greater than 20 seconds or so) observations.

In another test, I compared the binocular views of M 35 in Gemini, which had cliimbed out of the eastern murk, reaching a decent height just after local midnight. While both binoculars easily showed the large, roughly wedge-shaped open cluster, its sub-optimal altitude enabled only a few stellar members to be made out in the 8 x 42 but many more were discernible with the larger 10 x 50.

Some other daylight tests:

Many inexpensive binoculars often come with misaligned prisms which cut off some of the light reaching the eye. This is especially true when the product comes via courier. I’ve had a large 15 x 70 binocular in the past that came badly misaligned, which made me far more cautious about buying a binocular online. Thankfully, this was not the case with the Barr & Stroud binoculars, which were all properly and securely collimated in the factory prior to dispatch.

A simple way to test this is to examine the shape of the exit pupil of the binocular when pointed at a bright light source. A square or non circular shaped light shaft is an easy way to show if the prisms are undersized (thus losing some light) or misaligned. As the photo below shows, the exit pupils of the 10 x 50 are round, as are the 8 x 42s,  indicating that all is well.

No sign of a squared off exit pupil on the Barr & Stroud binocular.


Like the 8 x 42 previously tested, the 10 x 50 showed little sign of pincushion distortion while examining the profile of a horizontal roof located about 100 yards distant.

Attaining binocular stability without sacrificing mobility

As I stated previously, binocular astronomy, for me, generally means hand-held viewing, without the need for tripods or other more elaborate kinds of mounts that just get in the way. That’s one of the reasons why I eventually grew disillusioned with large and heavy binoculars. But any 10 x 50 unit, whether roof- or porro prism-based, will eventually show its limitations in regard to attaining rock steady views of star fields, or for teasing apart tighter binocular double stars, or even for seeing the most detail on the Moon. One way round the problem is to stabilise the binocular on a fence or a wall, but this convenience is not always practicle, especially if you’re on the move. The best compromise is to use a lightweight monopod and it is to this device that I turned to in field testing.

One thing the reader must be made aware of is that roof prism binoculars will not, in general, be compatible with standard porro prism binocular tripod adapters. Many of these adapters might fit the roof prism binocular but the stalk will more often than not be too wide to attain the optimum interpupillary distance so important for the most comfortable, immersive views. To that end, I ordered up a smaller adapter especially designed for medium sized (up to 50mm aperture) roof prism binoculars. I elected to go for a well machined, high-quality unit marketed by Opticron (shown below).

The Opticron tripod adapter designed for medium sized roof prism binoculars.

Having acquired a monopod some time ago for use in landscape photography, I was eager to see how the binocular would fare using this configuration, so I began a set of field tests using this device to see if it would tick all the boxes.

The Opticron adapter mates to the 10 x 50 Sierra very well, enabling the correct interpupillary distance to be maintained.

A good fitting: the Opictron tripod adapter mates to the binocular perfectly and will allow the user to re-adjust the interpupillary distance for optimum field performance.


The binocular with its adapter readily screws into the monopod. The whole configuration is still very lightweight, ultraportable and is now ready for testing under the night sky.

The 10 x 50 Sierra securely mounted on the lightweight monopod.

To what degree will the monopod stabilise the images in the 10 x 50? Off the bat, it will yield images that are more stable than an image-stabilised (IS) binocular, without the attending arm strain, high cost and need for battery power, but will fall short of that generated by a tripod.

Shortly before local midnight on the evening of November 15 2018, I stuck my head out my back door to discover that the sky had cleared somewhat after a rainy spell. The air was grand and mild, and the Moon had set shortly after 11pm, yielding a fine, dark sky. Pleasantly surprised, I ran in and fetched the 10 x 50 atop the monopod. The Pleiades was very high up in the south; ideally placed for binocular viewing. Settling into my recliner, I was able to negotiate a very comfortable position with the monopod securely held against the ground. Centring the asterism in the field of view, I was dumb struck by how good the view was; a blizzard of blue white stars piercing through the canopy of night in a blaze of glory! The effect of stabilising the view makes an enormous difference to what you see. Some highly experienced binocular users claim that you can go up to a magnitude fainter if the image is stabilised. I don’t know whether that’s accurate or not, but what I can say is that it was a supremely joyful experience. I just lay there for twenty minutes in the dark feasting my eyes on the celestial apparition before me. During the spell, cloud patches of varying thickness marched across the sky, diminishing the brilliance of the Pleiads by varying degrees, but as they passed through the full splendour of the cluster reasserted itself.

I will add a strong ball & socket adapter to the monopod so that I can make angular adjustments to the binocular. That way, I will increase the viewing comfort that little bit more.

That was my first experience with the monopod; a first step. In time, I’ll take another.

November 17 2018:

After rummaging around in me ole box of tricks, I selected a good ball & socket adapter for the 10 x 50 binocular. Although I had a few of these handy, I elected to use one that could carry the 780g instrument with ease. My best one, shown below, can carry cameras and other equipment up to 2 kilos in weight.

An all-metal ball & socket adapter mated to the monopod with a 2 kilo carrying capacity.


It worked really well with the binocular in daylight tests. Indeed, it will give me yet another degree of freedom whilst conducting my observations of the night sky.

Another view of the ball & socket adapter mounted on the monopod.


So, there it is; I think I’m ready for another session under the stars. What attracts me to this arrangement is its sheer simplicity; increased stability, easy to carry, easy to manoeuvre, easy to store away!

Simplicity itself.

Round about 6pm local time, I ventured out to see if the clear spells we enjoyed during the afternoon had persisted. I was in luck. The 10 day old gibbous Moon was low in the southeast, still a couple of hours before meridian transit. Eagerly, I turned the 10 x 50 astride the monocular mount at it, focused, and then carefully assessed the image.

I was very pleased! Our 70 per cent illuminated satellite showed some wonderful detail, easily superior to the smaller 8 x 42. The prominent ray crater, Copernicus, stood out a mile, as did Clavius and Tycho in the southern highlands. Eratosthenes, Plato and Archimedes proved easy too. The Apennine Mountains were clearly seen running from northeast to southwest and the various maria; Tranquillitatis, Fecunditatis, Serentatis, Nubium and Imbrium were all beautifully presented. Some faint stars in the vicinity of the Moon were easily seen in the 10 x 50. Thin, whispy clouds often ran across the lunar countenance, acting like a natural filter and increasing contrast. The upper edge of the Moon had a very thin bluish hue, whereas its southern counterpart was similarly tinged yellow. I attributed this in the main part to atmospheric refraction owing to its fairly low altitude (20 degrees) at the time the observation was made. Even at its brightest, glare was really well supressed, just like the 8 x 42 Sierra.

The Moon really comes alive in the image-stabilised 10 x 50!

The observations were conducted just standing up with the monopod, and I was able to tweak its pointing accuracy by making small adjustments to the ball & socket bearing. Turning over to the east, I aimed the binocular at Alpha Persei and made some more adjustments to the ball & socket so as to obtain the most comfortable standing observation of the binocular field. Even in bright moonlight, the rich starfields around it were wonderful and sharp almost all the way out to the edge, with excellent contrast.

Final testing: November 18-20 2018

Guid graith.

With unsettled weather being the rule rather than the exception over the last few days, my final tests were mainly conducted on a bright gibbous Moon, now rising much higher in the sky than previously reported on November 17. Whether seated, reclining or standing, the monopod is an excellent platform for image stabilised binocular astronomy, as it’s very easy to find a supremely comfortable position to conduct observations for all altitudes, from the horizon to the zenith. The lunar images remain sharp, with high contrast and very little in the way of glare evident to my eye. The extra image scale (25%) over the 8 x 42 is immediately appreciated, allowing lunar details to be more easily discerned at a glance. Some brief spells observing star fields in bright moonlight also produced very satisfying results. Suffice it to say that I cannot wait for the Moon to get out of the sky so that I can enjoy the wonders of the winter dark with this little instrument.

I have just one quibble with the 10 x 50; the soft carry case is identical to that which came with the 8 x 42. The case is ideal for the latter but is a little too small for the larger 10 x 50. Not a big deal but it should be said.

The Barr & Stroud 10 x 50 is the ideal astronomy binocular, offering exceptional perfromance at a price that meets most folks’ budgets. It’s solid construction, quality optics and very attractive price makes it an exceptional value in today’s market. Indeed, in an age where it is so very easy to get carried away by gimmicks and clever marketing ploys that pressurize individuals to depart with relatively large amounts of money, it is very reassuring to know that one can acquire this level of performance for a very reasonable financial outlay.

I heartily recommend these binoculars to stargazers everywhere and hope that they will give the reader as much joy as they have given me.

Thanks for reading.


Neil English is writing a new book dedicated to the ShortTube 80 achromatic telescope.


De Fideli.