Industar-50, silver lens for SLR camera
50 mm, f/3.5, M39X1/45.2 mount, s/n 6860699,
Krasnogorsky Mechanical Plant (KMZ), Krasnogorsk, USSR,1968

Very good condition. Lens is clear and does not have any fungus. Front glass has a lot of cleaning microscratches. Inside there are microspecks of microdust. Aperture ring rotates tightly. Focus ring rotates easily and a bit not uniformly. Both rings have backlash. Body has signs of age and use.

Camera "Zenit" is not included and is shown as an example of mount.
Note: this lens is for SLR only, it can be mounted to a rangefinder with M39 (LTM) mount, but it will not work. This lens can be mounted to SLR "Zenit", "Zenit-C", "Zenit-3", "Zenit-3M", "Crystal", early "Zenit E" and "Zenit B".

This is a standard lens for Soviet rangefinder and SLR cameras: "Zorki", "Zenit", "Crystal" instead of "Industar-22" lens. It was designed in 1953 and produced since 1953 till 1986. This lens was made in 1968 at Krasnogorsky mechanical plant named after Zverev (KMZ), also it was produced at LZOS (Lytkarino) and KOMZ (Kazan). The lens uses the "Tessar" lens scheme. The lens is anastigmatic and antireflected. Diaphragm numbering is doubled.

Lens had foldable and unfoldable versions, variants for SLR, rangefinder and enlarger.

This lens is very-very small and lightweight. You can easily put in your pocket, and the hardest camera will seem lighter with this lens. It is very cheap. But at the same time it has a perfect sharpness thanks to the "Tessar" scheme. Chromatic aberations are corrected. Bokeh is rather nice.

Characteristics: 
Lens s/number - 6860699
Number of lenses - 4 in three groups, Tessar.
Angle of view - 45o
Number of aperture blades - 7
Limit of aperturing - 1:3.5 (max), 1:16 (min)
Resolving power - (centre/edge) 38/22 lines/mm
Minimal distance of focusing - 0.65 m
Type of thread - M39x1/45.2 
Type of thread for the nozzles -  35,5 mm 
Dimensions (mm): 50*50*30
Focal distance - 52,48 mm.
Mass - 66 g