KOMZ 7x30 and 10x42

These Russian binoculars of apparently military origin are made by the Kazan Optical Mechanical Plant (KOMZ) in the Republic of Tartarstan.  They share common design characteristics and appear to use the same eyepiece design.  The bodies are rubber armored, with attached rubber objective covers, and are sealed with a waxy substance.   Also, a separate plastic eyepiece cover with storage for amber filters is provided (the amber filters seem redundant considering the yellow image).

The large eyepieces are individually focused, with a reticle on the right side.  The eyepiece design is the most sophisticated I have seen in a handheld binocular, with 7 elements in a 2-1-3-1 configuration (see the picture below).  This is very similar to the eyepiece design used in the Russian 30x180 binocular*.  A negative field lens is employed to help reduce field curvature and other aberrations, as in the  Nagler eyepiece design.  The eyepiece in the KOMZ is not exactly like a Nagler but looks more derived from the Abbe Orthoscopic design with its triplet.  The triplet has a yellow element, resulting in noticeably yellow images.  I am not sure if this was deliberate for military requirements or if a special glass type was selected to improve optical performance.  It is also possible that there is an aspheric surface employed, as the rectilinear distortion is practically zero.  Note that the view through these binoculars has a "rolling ball" effect (as the image rolls off the edge) also seen in other low distortion designs.  At any rate, the image is very sharp with pinpoint star images nearly to the edge.

An unfortunate by product of this eyepiece design is that the magnification (also FOV and exit pupil size) changes with the focus.  This is a result of the focus mechanism moving the negative element relative to the rest of the eyepiece.  This is not really an issue when both eyes have the same focus, but in the case when a person's eyes have different diopter settings, one side may have a different magnification than the other!  I have seen this eyepiece used separately as a zoom eyepiece for telescopes.  The fields of view given below are approximate due to the distortion and zoom characteristics of the eyepiece.

*Communications from Richard A. Buchroeder and Steve Stayton.

7x30

Mfr: KOMZ

Serial Number: 940181

Date: 1994

AFOV: ~59.5 degrees

TFOV: ~8.5 degrees

Eye Relief: 22.5mm

Prisms: high index

The particular sample of the 7x30 shown is an earlier model, marked with a red star and with internal focus style eyepieces.  I have also seen samples marked with the KOMZ "prism" style logo (see this web site for illustrations of some Russian optics logos) and with the external style focus (as seen in the 10x42 below).  The internal focus mechanism may be more elegant and better sealed , but unfortunately the eyelens is recessed more than 10mm in this design.  The rubber topped metal eyecups do not appear to be easily removable, so much of the generous eye relief is lost, especially when using glasses.

10x42

Mfr: KOMZ

Serial Number: 990184

Date: 1999

AFOV: ~58 degrees

TFOV: ~5.8 degrees

Eye Relief: 21mm

Prisms: high index