Review: Kronos BPWC2 6x30 binocular

by Holger Merlitz

This Russian binocular is produced at ZOMZ (Zagorsky Optiko-Mekhanichesky Zavod), a plant which has since long achieved a reputation for optical instruments like camera lenses, among others. Russian binoculars are specified by their optical scheme -- probably a heritage from Soviet times. Here, `B' stands for binocular, `P' means Porro prism, `W' means wide angle, and `C' indicates central focusing. `2' seems to indicate a successor of an earlier instrument, although I have not come across such a device yet. I got this binocular at for about 70 Euro. It was delivered with a handy soft bag, plastic lens caps and a Cyrillic instruction manual. I suggest to keep the lens caps at home since they are loose enough to get lost anyway. Also, the objective lenses of the Kronos are well buried deep enough inside the housing so that hardly anything harmful could happen to them. There are further versions of this glass in the product line, namely a 7x35, 8x40 and a 10x50, all of them with ultra wide angle and a similar price tag. They are advertised as military binoculars for sky surveillance, and claimed to be operational within a range of -30 to +45 degrees Celsius. They are claimed to be rain proof, but this certainly does not mean water proof.


The BPWC2 has got a full metal body which feels solid and rugged. Among the most striking construction features are the huge wide angle eyepieces with about 20mm lens diameter. The eye relief is claimed as 17.5mm which is more than sufficient for a comfortable observation. The central focus wheel however feels somewhat loose, and there is a little play in the linear guiding of the eyepieces. The camouflage painting looks a bit kiddy -- but this is a matter of taste, of course. There is no reticle.

The Zeiss 8x30W (left), the Kronos 6x30 (center), the Hensoldt DF 8x30 (right)

A large eyepiece and a bulky prism housing are among the features of the Kronos

The central focus is a weak point of the russian glass


The evaluation of an optical instrument is much easier when there are other items at hand for comparison. Lacking any binocular with exactly the same specification, I have chosen the Zeiss Jenoptem 8x30W and the Hensoldt DF 8x30 as competitors. Both are since long known to be very solid performers. The Jenoptem was produced at East German Carl Zeiss Jena plant and is an instrument for civil use. The DF was built during the 60s and 70s as one of the main NATO military binoculars. The Jenoptem is a multi-coated, wide angle glass, whereas the DF is singly coated but with a similarly wide angle. I have no official technical specifications for the Jenoptem at hand, but the DF officially got 8.5 degrees of field and I see little difference to the Zeiss. In real application I rather found the angle of view to be little above 8 degrees for both of them. It may be that the eye relief is so short that it is difficult to see the full angle. The DF has got a reticle and a rubber armoring, the Jenoptem is without. Both can be purchased second hand at E-bay in reasonable condition for about 100 Euro.

The table summarizes some of the specifications of the contenders.

Table 1:
  Angle of Eye relief Exit pupil Weight
  view (deg) (mm) diam. (mm) (kg)
BPWC2 6x30 12.5(a) 17.5 5.0 0.75
Jenoptem 8x30W 8.6(a) 12 3.8 0.55
DF 8x30 8.5(a) 12 3.8 0.65

a : Official values; Actually: 11+ (Kronos), 8+ (Jenoptem), 8 (DF)

Optical performance

Center of field: All binoculars are flawless. They give a crisp and bright image. Stars are perfectly point like, there is no chromatic aberration visible (at the magnification range of 6-8, however, one can expect the device to be free of chromatic aberration). The DF and the Jenoptem display a neutral image color; the image of the Kronos looks slightly yellowish. There has been plenty of speculation about why Russian glasses (as well as the East German EDF 7x40 ) have this yellowish tint. I do not believe the story about ingredients to protect the optics against radioactivity, supposed to prevent fogging. If a radiation level gets high enough to fog glass there won't be anybody around anymore to worry about. But it has been observed that the yellowish color improves contrast under gloomy and misty conditions. In fact many military grade binoculars come with yellow filters to achieve this effect.

Angle of view: The Kronos has clearly got the widest field of view. I could not convincingly prove the huge angle of 12.5 degrees as given in the specification; but I estimate more than 11 degrees are there for sure and this is fine anyway.

Outer field performance: All wide angle binoculars are prone to stray light which is scattered from the internal boundaries of the housing. This leads to a diffuse ring of light close to the outer edge of the field, reducing contrast. This effect is most annoyingly visible in the Jenoptem. It is significantly less in the Kronos and even less in the DF. One can explain the poor performance of the Jenoptem with the fact that the housing is quite slim here; the inner tube which leads from the objective lens to the prism is just wide enough to accommodate the prism, whereas in the DF and Kronos this tube is wider than the prism so that stray light can't go straight through the optical path. This extra space is missing in the Jenoptem, leading to a slim and light weight construction, but making it suffer from stray light. Coma and astigmatism are present in the outer fields of all glasses. Image degradation is visible in the outer 20% of the Kronos and the DF, the Jenoptem is a little worse and shows the same effects in the outer 25% of the field. One should not over-emphasize such effects, however. These are wide angle glasses and the resolution of the human eye is low far out of center as well. The wide fields of all glasses allow to overview the scenery, and once something interesting happens close to the edge one will turn the glass and get it into the center where the image is perfect. In contrast to camera optics, which creates a static picture, the binocular picture is dynamic and doesn't need to be perfect up to the outer edge.

Low light performance: The Kronos has clearly the brightest image at low light, but this is not too surprising, having the largest exit pupil diameter. But it indicates that the multi coating of the binocular is well done and I suspect it is better than the coatings of the DF, which is certainly not state of the art any more. Both DF and Jenoptem perform evenly well, although the reticle of the DF can be a bit disturbing. I could not verify whether the Kronos actually shows `more' in low light. I checked with the fine structure of a tree trunk in the evening, and all glasses displayed about the same surface detail. In fact, the Kronos image was brighter, but the others had more magnification. In other words: They have better resolution, but at lower contrast. Both effects seem to compensate each other, as long as the residual light is strong enough - at a certain point, however, it is only the Kronos with its larger exit pupils which is able to display a 3-dimensional image.

Mechanical quality

The three binoculars are made of aluminum. Although nowadays high quality plastic materials are available which are practically indestructible, it seems that both machining accuracy and temperature behavior do still favor metal bodies.

The central focus of the Kronos is disgusting. It is so loose that the binocular is easily defocused accidentally when handling it around. In contrast, the focus of the right ocular is well done and without slop. Also, the inter-ocular distance adjustment feels very solid. The Kronos is the heaviest among the three binoculars, featuring the largest prism housing and oversized eyepieces. But with 0.75 kg it rests well in the hands and provides very steady free hand observations. The machining of the Jenoptem is flawless. It is lightweight but solid. The DF, being a military glass, has individual ocular focusing and is built very well and rugged and is still lightweight. It is the only water proof device among the three competitors.


The Kronos BPWC2 is an impressive performer. It is optically superior to the Zeiss Jenoptem and on par with the Hensoldt DF, but at a wider field of view. Mechanically it is fine -- with exception of the loose focus which looks like a design flaw. The Kronos displays a patchy mixture of military and civil features. Perhaps, it is the successor of something which was originally a full fleshed military glass. The oversized eyepieces with large eye relief, the slightly yellowish image and the altogether very sturdy design indicate its non civil heritage. Perhaps, in the process of civilization, the reticle was removed, and the central focus was introduced, which was possibly not a good idea. The glass is certainly not waterproof with its sloppy focus. If I could pass one advice to the ZOMZ construction team: Go back to individual ocular focusing, because here you know well how to do. Then the entire construction would be sound and consistent.

The Jenoptem is optically a little disappointing, considering its proneness to stray light. But it is more compact and lighter than the military based glasses. It actually looks a bit undersized for a wide angle, and this is perhaps one key to understand its poor protection against stray light. On the other hand, being a civil glass, it is supposed to be mobile and create fun, so one may excuse some minor flaws in the image. To get one point straight: It is still much better than most of the products of this price range on the market today.

The DF is a well balanced design. Although neither optically nor mechanically on top of the world, it provides no weak point, is rugged and water proof but still of low weight and can be easily repaired. Not accidentally it had been chosen to be a central player in NATO's optical equipment for many years.


The information given in this report reflects the personal impression and opinion of the author only. I cannot guarantee for the accuracy of any given specification. I have neither been payed nor have I been supported in any other way to write this review.

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Last updated: 2003