Russian 1PN-51 improved Night Vision Device
The Russian 1PN51 scope is a "second generation" night vision optic that gives a slightly less blurry picture than the first generation of night vision devices and no "fish eye" distortion. 1ПН51 (НСПУ-3 "Казуар") Also known as the NSPU "Kazuar" scope, it is a "passive" scope that does not use any infra-red illumination source.
The Kazuar is a 2nd generation night vision device designed during the Soviet era, indeed shortly before the collapse, and was the flagship of the optical technology of the time. Like the earlier 1pn58, it is still employed by the Russian Federation.
The mount has a cam adjustment for use on all Russian small arms, including AS / VSS and AKSU.
The 1pn51 has 3x magnification and is equipped with both ABC (Automatic Brightness Control) and BLP (protection in case of bright light), both very useful when working because of the sensitivity of the intensifier tube. Tube life is approximately 3000 - 4000 hours.
Powered by a rechargeable 6.25 volt multicell battery, (similar to the 1pn58) the Kazuar is more compact and slightly heavier than the 1PN58, at about 2kg, but with a wider lenticular opening at about 90mm.
The controls are almost identical, with a single wheel that controls the brightness of the reticle, to allow the best adjustment from observation to engagement.
The diaphragm for daytime use is mounted with a rubber gasket secured with two lateral pins, and has two round windows for the entry of light.
The window openings are controlled by a lever which ensures a rather precise adjustment in steps.
The ability of light intensification the 1pn51 in darkness is very good, as is the reliability, starting from the shell magnesium alloy passing through the systems of electronic protection of which is fitted.
The brightness of a city lights is too high to allow you to remove the diaphragm and what can be seen with the 1PN58 without the light filterting diaphragm looks the same on the 1PN51 WITH the diaphragm fitted.
Of course, being a second generation system, there is no lens distortion or fisheye effect as in the 1PN58 scope.
The reticle is illuminated by an LED bulb.
A quote found on a discussion forum from a Russian member:
"The Soviet army for the most part was an extremely mobile force. The infantry fought by the side of their tanker comrades, though a scope like that would never be issued to your lowly infantry marksmen. The 1pn51 has primary been used by the "top" for most of its service time. Now it is slowly coming into the hands of less "elite" forces like VDV etc. The scope itself I find balances out the SVD because its design does not make it too front or back heavy. There are cheaper Soviet scopes out there but they are only Gen 1+ and lower. But they are really fun to use and I am sure would serve you better then the naked eye. I have one called the NPSU or 1PN34 I think it is a great scope."
The 1PN51-2 night vision scope has an improved scope mount which allows a better fit to the RPG rail (as well as the standard Russian dovetail optics rail on the usual rifles, LMG, etc). The 6 volt battery is now mounted horrizontally which gives it a lower profile.