Jupiter-12 2.8/35 black USSR lens rangefinder Kiev LZOS Contax RF mount

Jupiter-12
black lens for rangefinder camera
35 mm, f/2.8, Contax (Kiev) mount, s/n 6904233, 
LZOS, USSR, 1969

Very good condition. Lens is clear and clean, does not have any fungus. Front glass has cleavage dot. Inside there are microspecks of microdust. Aperture and focus rings rotate properly. Body has small signs of age.

Camera "Kiev" is not included and shown as an example of mount.

This is the copy of "Carl Zeiss Jena Biogon" 2.8/35. Firstly was called"BK-35" (Biogon from Krasnogorsk, 35mm). It was made at three plants: KMZ (Krasnogorsk), Arsenal (Kiev) and LZOS (Lytkarino). In 1947-52 lenses were made with lensblocks from Western Germany. In 1952 KMZ started to make it own lenses entirely.

Lenses were made with two mounts: Contax (for "Kiev" rangefinder) and M39 Leica screw mount (for "Zorki" rangefinder). Had two colours of body: silver and black. Silver lenses are better for black-and-white film and black lenses are better for colour film.
Lens is wide-angle and has one-layered multi-coating.

haracteristics: 
Lens s/number - 6904233
Number of lenses - 6 in four groups
Angle of view - 62o50; 
Number of aperture blades - 5
Limit of aperturing - 1:2.8 (max), 1:22 (min)
Resolving power - (centre/edge) 34/12 lines/mm
Minimal distance of focusing - 1 m
Type of thread - Contax RF mount
Type of filter thread - 40.5x0.5 mm
Dimensions (mm): 57*57*58
Focal distance - 35,75 mm.
Mass - 118 g
One-layered anti-reflection coating