The Jupiter-12 35 mm f/ 2.8 (Russian: "Юпитер") is a wide-angle lens with an iris aperture and a single-layer coating for rangefinder Zorkiy type cameras with the m39 Leica screw-mount (LSM). It was also produced in a bayonet variant for Kiev rangefinder cameras, the Contax I-III system (CRM).
Its optic scheme was borrowed from the Carl Zeiss Biogon 2.8/35. Initially, it was named BK-35 (Biogon of Krasnogorsk). Besides the Krasnogorsk mechanical works (KMZ), the Jupiter-12 was produced at the Lyktarinsk Optic Glass Factory (LZOS).
The Jupiter-12 BK came into production at the KMZ in 1947. It was based on optic units delivered from Eastern Germany as war reparations. The lenses were designated with the old brand mark – the Dove prism without ray course - and were produced for three years. Since 1949 the second version of the lens came to be produced in visually more massive body, but without the designation "BK". The logotype was also changed: the ray course was added to the prism (however, there were products contradicting the official version - for example, the lens numbered 5000003 with the following inscription: BK, 1:2.8, F =3.5 cm, P (red-colored), ZORKIY. And that's all).
Since 1952 the Jupiter-12 was supplied with lenses produced in Krasnogorsk. Since 1956 it was produced with the FED and Zorkiy barrel. The retail price of such lenses was 28 rubles in 1985. For the lens the factory produced appropriate viewfinders fixed in slots for a rangefinder camera accessories.
Angle of view: 63°
Resolution according to the technical specifications (centre/edge): 34/12 lines/mm
Coefficient of transparency: 0.75
Posted by: Bruin Date of publication: 23.02.2011