Barr & Stroud Sierra 10x42 Binoculars Review

The Barr & Stroud Sierra 10x42 roof prism binocular is a binocular that I really looked forward to reviewing. The manufacturers themselves describe their range of Sierra binoculars as "a blend of superb optical quality and rugged refinement that has produced an elegant range of binoculars that take the Barr & Stroud brand to new level of performance and sophistication" and I really liked the more compact 8x32 Sierra that I have already reviewed.

The 10x42 Sierra Body

The dimensions (135x125x52mm /5.3x4.9x2.0in) of the Barr and Stroud 10x42 Sierra binocular is pretty compact for a 42mm binocular, for comparison the top of the range Zeiss 10x42 Victory FL Binoculars are 6.81in (173mm) long and 5.43in (138mm) wide.

Their weight of 23.7oz (673g) is fairly lightweight: For comparison one of my favorite 42mm binoculars, the Nikon 10x42 EDG Binoculars weigh 28.9ozs (819g) and the top of the range Leica 10x42 Ultravid HD binoculars weigh 26.5ozs (751g).

In the hands, the binocular feels comfortable to hold, is well balanced and the rubber armor that covers them has a number of benefits that you may not have thought of:

• It provides a secure and comfortable surface for making them easier to hold on to
• It helps protect the binocular from the bumps and scratches that come with day-to-day use
• It's easy to wipe clean after a tough day in the field
• It dampens down any noise from bumping them that could frighten away skittish birds and other wildlife as I often do with my wedding ring.

Waterproof & Fogproof
Like all of the Sierra range, these 10x42's are O-ring sealed and are therefore fully waterproof and have been immersion tested at a depth of 1.5 meters for three minutes. They have also been "nitrogen purged", which means that the air inside the binocular has been replaced with nitrogen gas. This prevents the interior optical surfaces from fogging up due to rapid temperature changes or in areas that have high humidity.

The Eye Cups
As with all the Barr & Stroud binoculars that I have reviewed, they have twist-up eyecups. The ones on these however are even better quality than most as they are made of metal with a rubber coating for comfort. The twist up action has 3 click stops - flush against the eyepiece, half-way out or fully extended. Non-eyeglass wearers will use the eyecups in the fully extended position. There is a decent 14.2mm of eye relief, which does not put them in the category of long eye relief binoculars, but in most cases an eye relief of 14 to 15mm is adequate for most people who wear glasses to be comfortable.

Focusing
Focusing is achieved using the central wheel on the binocular that takes 2 full turns to go from near focus which is an excellent 2m (6.6ft) to infinity. I generally prefer a focusing wheel to take less turns to achieve this, but the less aggressive focusing mechanism does have the advantage of making fine tuning your focusing more accurate. On the binoculars that I tested, the mechanism was smooth and achieving a sharp focus was really simple.

The diopter adjustment is located on the right barrel of the binocular. It allows you to adjust the lenses separately to allow for differences in each of your eyes and plays an important part in correctly focusing your binoculars. The ring on the 10x42 Sierra that I tested was just tight enough so as not to be easily accidentally moved, but not so tight that makes it hard to adjust.

Barr & Stroud Sierra Optics

Like the 8x32 Sierra, I thought that the image produced by the full size roof prism Barr & Stroud Sierra 10x42 was really good. As well as bright I thought the image was sharp and I could not see any colour fringing and there was only the slightest hint of softening of the image on the periphery of the view. You can just notice the difference in brightness when comparing them to the more compact version and so if you are looking for performance over size, I would definitely choose the larger 10x42.

Lens & Prism Coatings
The 10x42 Sierra comes equipped with quality BaK-4 roof prisms which means that they are made of superior optical glass that will help in ensuring you get a high-contrast and sharp picture over the full field of view. These binoculars also have a set of phase correction coatings on the prism glass, this is an expensive process that keeps light in correct color phases, yielding brighter images and higher edge-to-edge sharpness. According to the manufacturers the "high-tech phase coatings alone increase prism reflectivity by 8% and it give you on average an extra hour of visibility at dawn and dusk compared to standard binoculars."

The optics are also fully multi-coated, so all air to glass surfaces have received multiple layers of antireflection coatings which again will ensure that more light gets to your eyes by reducing the light loss and glare due to reflection for a brighter, higher-contrast image.

Accessories

The Sierra 10x42 comes supplied with reasonable quality soft carrying case, straps and lens cleaning cloth. It is a pity that the straps are not more padded, like the ones that you find on more expensive optics, but they will do the job (see video below).

The lens caps fit well onto the binoculars and should not fall off accidentally. I especially like the tethered objective lens caps, that make misplacing them much harder and don't get in the way when using your optics. If you don't like them attached to your binocular, they can also be removed (see video below).

Stats

10x42 binoculars like these Barr & Stroud's have an Exit Pupil of 4.2mm and a Twilight Factor of 20.49, both of which point to the fact that they will more than will hold their own in poor light conditions and whilst they may in theory not quite perform as well as an 8x42, these have the advantage of getting you closer to the action with the more powerful 10x magnification. It is important to remember that whilst these figures do not take into account the quality of the prisms, lenses and their coatings, they do make it possible to compare the performance of different configurations of binoculars in low light conditions. Features like their phase coated Bak-4 prisms and fully multi-coated lenses mean that they will outperform cheaper 10x42 binoculars with lower quality lenses, coatings and prisms.

The apparent field of view for the Barr & Stroud Sierra 10x42 is acceptable 101m at 1000m / 304ft at 1000 yards but does fall a short of the very best like the Swarovski 10x42 EL Binoculars (330ft at 1000 yards / 112m at 1000m) and the Nikon 10x42 EDG (341ft at 1000 yards). It must be remembered that these high end optics are more than 10x the cost of these Sierra's.

The close focusing distance is an excellent 2m (6.6ft) beating even the most expensive mid-size binoculars on the market, a important consideration if you enjoy close observation of small creatures like butterflies.

Conclusion

Considering that the Barr & Stroud 10x42 Sierra can be bought for around £100, I would say that like all of the Sierra range, they make excellent value for money. I would highly recommend them to anyone looking for a mid to entry level full size binocular that far outperforms their price tag. They make great wildlife observation binoculars, great to take to sporting events and good general all rounder's. The 10x magnification is great, but the slightly smaller field of view means that unless you are observing birds in wide open areas like water birds, you may wish to consider the 8x version for birding. Highlights include the close minimum focusing distance and the use of quality phase coated Bak-4 prisms.