Product Review: Nikon Prostaff 7S 8 x 30.

The Nikon Prostaff 7S 8 x 30.

In recent years, a flood of high-performance 8 x 30 roof prism binoculars have hit the market to cater for the demands of birders, hunters and nature enthusiasts looking to blend the comfortable and immersive performance of larger 42 and 50mm models with the smaller and lighter frames usually only found in compact or pocket binoculars. For example, Swarovski have successfully launched their CL Companion in 8x and 10x 30mm formats and Nikon have introduced a range of 8 x 30 models varying both in price and quality. While their flagship model – the HG 8 x 30 – retails for about the same price as the CL companion(£800 to £900 UK), Nikon also offer a number of more economically priced units in their Monarch 7 and Prostaff 3S, 5S and 7S models.  Curious to test out one of these models, I took a punt on the Prostaff 7S 8 x 30 model, which I was able to buy at a cost of £139 including delivery. Was it worth the cost? Absolutely yes! To see why, read on.

The package was boxed away nicely and included the 8 x 30 binocular, a quality padded neck strap, an instruction manual in a number of different langauges, and plastic rainguard and objective dust caps. The Prostaff 7S also comes wth a 10 year (non-transferable) warranty.

The Nikon Prostaff 7S 8x 30 package.

My decision to purchase this unit was not entirely blind however. I became most intrigued by a very favourable review of this binocular from Allbinos.com as well as a string of positive reviews posted on amazon.co.uk.  Allbinos have cultivated a good reputation with die hard binocular enthusiasts owing to their impartiality and stringent testing regimes. That this binocular did so well in their tests is not surprising(in retrospect), as you’ll soon discover!

First Impressions: The binocular arrived in perfect condition. From the moment I first prized the instrument from its soft, black carry case, I was very impressed with the fit and feel of the instrument. The Prostaff 8 x 30 is exceptionally light weight; just 415g in fact, thanks to a tough, polycarbonate body overlaid by a thick, textured rubber overcoat with excellent grip. That makes it even lighter than the 8 x 32 Celestron Trailseeker(453g) I have been using in recent times. The focus wheel is exceptionally smooth with absolutely no backlash when racked clockwise or anti-clockwise from one extreme of focus travel to the other, and is also overlaid by the same thick rubber that attends the body armouring, making it wonderfully easy to manouevre either with or without gloves. From end to end, the focus wheel rotates through about 340 degrees (so less than one revolution), which translates into a very quick and responsive way to get from close up to far away with very little effort.

The Prostaff 7S 8x 30 has high quality twist-up eyecups for comfortable use with or without eye glasses.

The dioptre adjustment is located in the standard position for most binoculars offered at this price point; that is, under the right ocular lens. It is rigidly held and has a mark on it which enables the user to precisely record the optimum position for one’s eye. The unit is water proof(10 minutes at 1m depth), O-ring sealed and nitrogen purged to prevent internal fogging and corrsion of any metal parts housed inside the barrels. The eyecups are of high quality, rubber-over-metal and have four positions from fully down to fully up. They hold their positions very well, even when considerable pressure is applied to them, and stay rigidly in place in routine use. I found that the most comfortable position for my eyes was to extend them fully upwards, where they provide a comfortable 15.4mm of eye relief. That’s good enough for both eyeglass wearers and those(like yours truly) who prefer to view without glasses. The instrument is 11.9 cm long(with the eycups fully down) and 12.3 cm width(fully extended)

The black and gold livery of the Prosfaff 7S 8x 30 is very eye-catching.

The bridge has a single central hinge that enables one to adjust the IPD with just the right amount of tension so that once adjusted, they maintain that position very well.

The Nikon Prostaff 7S 8 x 30 comes with a plastic rain guard to cover the eyepiece lenses and plastic objective caps that clip tightly into the recessed part of the objectives. Some folk have cried foul of these because they are plastic but I’ve not had that experience. I actually prefer them to the regular synthetic rubber caps since they remain tightly in place and so do their intended job  perfectly well.

Ergonomically, this little bino was a very pleasant surprise! I have always found the Celestron Trailseeker 8 x 32 quite tricky to hold in my rather small hands(for a bloke) well owing, to its very large central bridge. As you can see from the photo below, compared with the Celestron, the Nikon Prostaff 7S has a shorter bridge which enables me to wrap my hands firmly ’round the top end of the barrels much more effectively, whilst enabling me to focus using my left index finger.

The Nikon Prostaff 7S 8 x 30(right) has a significantly shorter central bridge than the Celestron Trailseeker(left), making it much easier to grip with both hands. Note the absence of a tripod stalk on the Nikon, which also frees up some space.

Another good design feature of these Prostaff 7S binoculars is their deeply recessed objective lenses, which affords protection from dust and rain, as well as serving as a barrier against the contrast-robbing peripheral glare.

The objective lenses on the Prostaff 7S are deeply recessed.

Optical Testing

The specifications supplied by Nikon state that the Prostaff 7S is fully multi-coated with a phase coating applied to the roof prisms. Light throughput is boosted by a mirror coating(possibly aluminium but more likely silver). By itself, these statements are meaningless unless one assesses the optical performance of the binocular in person. Indeed, I had learned from previous acquisitions that you don’t always get what you pay for.

But right from the get go, this little Prostaff impressed. As is my usual custom, I started by testing how good the binocular handled stray light and glare but performing my iphone torch test. This involves turning my torch up to its brightest setting and aiming the binocular directly into the light from just a few metres away. The result was excellent! Compared with my control binocular; the 8 x 42 Barr & Stroud, it showed an equally clean image, with no diffused light and only the merest amount of internal reflections. The Prostaff 7S did exhibit a fairly prominent diffraction spike though – which is common in roof prism binoculars –  much more than in my 8 x 42 control, which shows only the merest trace of a spike in comparison, but less intense than in my Zeiss Terra pocket glass. Testing the binocular on a bright sodium street lamp at night also showed excellent results, with no annoying internal reflections, excellent control of glare and a very modest diffraction spike. These results convinced me that the binocular ought to produce excellent contrast in daylight images, especially when pointed at strongly backlit subjects.

The Nikon Prostaff 7S 8x 30 passed my iphone torch test with excellent results. The Barr & Stroud 8x 42 control binocular(right) was used as a suitable control owing to its superb suppression of stray light.

Glassing a variety of targets in the open air yielded impressive results too. The image was tack sharp, with great colour rendition and contrast, and it remaiined very sharp from the centre to the very edge of the binocular field. The binocular exhibits very mild pincushion distortion as judged by examining a telephone pole moved from the centre to the edge of the field stop. The brightness of the image was also noteworthy. Despite its lack of the highest reflectivity dielectric coatings, the binocular completely outperformed my 8 x 25 Zeiss Terra(a first-rate pocket glass) in low light conditions at dusk, but was very comparable to the brightness served up by the Celestron 8 x 32, which does have those dielectric prism coatings.

The Allbinos review measured the light transmission of the Prostaff 7S 8 x 30 at about 87 percent; which seems very credible to me. But what’s even more interesting is that it had a higher light transmission than the more costly Monarch 7 – measured at 85 per cent – which has ED glass objective elements.  This provides further evidence against the commonly parroted notion that ED binoculars produce brighter images; they do not! Brightness is much more strongly linked to the quality of the coatings applied to the lenses and prisms in the optical train. The Monarch 7 does have dielectric coatings however, so the Allbinos test result was a little surprising. There is a rational explanation though; having a significantly larger field than the Prostaff 7S, the Nikon Monarch 7 likely has a more complex optical design. And that usually means one or more extra optical components are needed to produce its very large (8.2 degree) field of view.  Indeed, if you look at the transmission data for a variety of ED and non-ED binos made by different manufacturers tested and published by Allbinos, you’ll soon see that ED glass does not, in itself, equate to brighter images.

As the reviewers on the Allbinos website remarked about the Prostaff 7S’  light tramsmission;

They didn’t stint on coatings, though. A transmission level in a wide range of the spectrum not much worse than 90% is something you don’t see often when it comes to roof prism binoculars sold at this price point.

The reader will also note that the state-of-the-art Swarovski CL Companion 8 x 30 has a transmittivity of 90 per cent(as published on  the Swarovski website), so the Prostaff 7S 8 x 30 will more than hold its own against it in low light conditions.

The larger exit pupil (3.75mm) on the Nikon Prostaff 7S makes for much easier positioning of one’s eye sockets than in smaller pocket glasses, which results in very comfortable, immersive glassing, even during prolonged field use. The silky smooth focuser makes this instrument particularly nice to use. Indeed, this little Prostaff has re-kindled my interest in both 30 and 32mm formats because of their sheer versatility. All of these findings raise an interesting and legitimate question: how can Nikon produce such a great performing binocular and market it at a relatively low price point? The answer, to some degree, pertains to its smaller field of view –  just 6.5 degrees. Most binoculars with these specifications have significantly larger fields – usually from about 7.5 to 8.3 degrees. Nikon obviously decided to restrict the field of view so as to maintain excellent image sharpness from the centre to very near the field stop. And that’s entirely understandable. I would personally prefer a smaller, sharper field than a larger one which blurs significantly as one moves out of the central sweet spot. And 6.5 degrees is plenty wide enough. I certainly don’t subscribe to the philosophy that once you regularly experience a 8+ field, there’s no going back. Besides, I already have a most excellent wide angle 8 x 42 binocular which delivers a very expansive 8.2 degree(143m@ 1000m) true field.

Another cost-cutting measure is to use a synthetic polymer to house the optics. This is quite acceptable too, as polycarbonate frames have been tried and tested with many other binocular makers over the years. It also shaves off additional weight to render the instrument lighter and more portable.

Many binoculars display a marked drop off in brightness towards the edges of the field. Not so with the little Nikon Prostaff 7S 8x 30! Indeed, I could detect little or no attenuation in brightness around the periphery of the field during daylight hours, which does add more aesthetic punch to the image garnered by this lightweight roof prism binocular that will certainly appeal to almost anyone who uses it. Chromatic aberration is very well controlled, but like most any quality instrument of this nature, it does show a trace when examining a high contrast object like a telephone pole against a bright background sky and only if you go searching for it. Like I said before in other binocular reviews, any discussion on chromatic aberration in well-made modern glasses like these amounts to little more than drivel.

The underside of the Nikon Prostaff 7S 8 x 30 binocular.

So, to sum up the daylight performance of these 8 x 30 binoculars, I would agree wholeheartedly with the concluding comments proferred by the reviewers at Allbinos:

For a quite moderate amount of money you get an optical instrument without any serious flaw. Due to its physical dimensions it might become your loyal and efficient companion on different trips……………….. we are very pleasantly surprised by the performance of the small Nikon – let’s hope there are more and more such good instruments available on the market. 

Note added in proof: My hunches regarding the lower light transmission of bigger, more complex binoculars appears to be corroborated in this Allbinos review of the Vortex Viper HD 10 x 42. But there are many other examples one can point to by means of illustration.

Ad Astra

Having in my possession a modest collection of binoculars from 20mm up to 60mm aperture, I can say, hand on heart, that 30mm is about the minimum that I would be happy with for regular stargazing. This, of course, does not at all detract from my ongoing blog using smaller pocket glasses, where I wrote (and continue to write) about using these small instruments on the basis of, ” what if these were your only binocular?”

Yes, a 30mm aperture binocular will be vastly superior to a 20mm or 25mm glass when it comes to viewing the heavens. The larger aperture of the objectives and the larger exit pupil render this possible. The Prostaff 7S 8 x 30 pulled in significantly more starlight on virtually all objects I tested the glass on. Views of the showpiece objects, such as the M35, M36 to M38, the Pleiades and Hydaes, the Double Cluster, the Beehive Cluster(M44) and the Coma Berenices Cluster were very nicely rendered in this binocular with excellent contrast, while scanning the late winter Milky Way was a very pleasant experience indeed. Because of its nearly flat field, stars remain sharply focused nearly all the way to the field stop, and I was able to verify the true field of this binocular as being very close to the manufacturer’s published figure of 6.5 angular degrees. I was only just unable to image the two stars at the end of the handle of the Ploughshare(Big Dipper) – Alkaid and Mizar – within the same field. These stars are separated by 6.67 angular degrees.

Overall Conclusions

Worth the price: the Nikon Prostaff 7S 8 x 30 does what it says on the tin.

By most anyone’s standards, the Nikon Prostaff 7S 8 x 30 provides excellent ergonomics and optics given its very modest retail price. And now that the media has decimated the world economy through shameless scaremongering over the coronavirus, this would be a good binocular to acquire if you’re on a tight budget. Personally, I prefer it to the 8 x 32 Celestron Trailseeker(now bequeathed to my my eldest son) because of its superior handling, lower weight, better corrected field and similar light transmission. It’s a joy to use and should give its owners plenty to crow about for many years. In an age of deceptive advertising and influential binocular shills, the Nikon Prostaff 7S 8 x 30 could be all the binocular you might ever need.

 

Highly recommended!

 

Dr. Neil English is the author of seven books on amateur and professional astronomy. Taking no prisoners, he has dedicated much of his writings to de-bunking scientific and obsevational myths promulgated by fake gurus and armchair amateurs who wouldn’t know the North Star from Uranus.

 

De Fideli.

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