The Jupiter 9 is an 85 mm f/2 lens made in the Soviet Union. It is based on the design of the Carl Zeiss Sonnar, after the technical information, and machinery were taken from Carl Zeiss in reparations at the end of the Second World War. Production began in 1948, when the lens was initially called the ЗК-85 (Sonnar Kransogorsk) and it was assembled using mostly German parts in Contax/Kiev mount. The lens was also adapted to Zorki (M39) mount to fit the Zorki cameras early in production.  It appears, for both Zorki and Kiev mount, in a 1949 catalogue. By 1951 the name changes to Jupiter 9 (Юпитер-9).
The lens has seven glass elements in three groups; a single glass at the front, and two cemented groups of three. All versions of the lens are coated.
It was made by the KMZ and LZOS factories, in Leica 39 mm thread mount for Fed and Zorki rangefinders, but originally it was a Contax bayonet used in Kiev cameras. Jupiter-9 lenses were also made at the Arsenal factory in Ukraine, for Kiev rangefinders,but initially released as KMZ, later it was also used for the Kiev Automat SLRs (such as the Kiev 10), in their own bayonet fitting. This version of the lens has no aperture ring; the aperture is set with a control on the camera, next to the lens mount, as part of the auto-exposure system. It was later adapted for M42-mount Zenit SLR cameras, and there is also a version for the Narciss subminiature SLR camera for 16 mm film, with an M24×1 thread mount.
The lens went through cosmetic and design changes  during it's long production life. Early versions of the lens are in polished aluminum bodies, as pictured here. Later lenses are black.
The rangefinder version of the Jupiter-9 focuses to 1.15 m; the Zenit versions focus to 0.8 m.
Optical formula from OPAL database
Cистема-Юпитер-9 f'=83 2w=25 1:2 Nsurf radii thick heig glass reflaction indices L= .546070 .435830 .656280 air 1 46.450 5.600 25.230 ТК16 1.615193 1.625734 1.609501 2 268.500 .400 20.500 air 3 25.940 5.800 20.400 БФ13 1.642767 1.656355 1.635656 4 52.000 7.500 17.550 К1 1.500095 1.507625 1.495907 5 -264.200 1.800 15.250 ТФ2 1.677619 1.699829 1.666600 6 16.444 13.800 7.200 air 7 -1043.650 2.800 7.200 ОФ1 1.531924 1.542250 1.526400 8 44.510 10.600 6.900 БФ13 1.642767 1.656355 1.635656 9 -15.031 2.900 7.400 БФ7 1.582158 1.593071 1.576359 10 -95.060 8.950 air aperture is 6mm after 6th surface, d=12.5
- Jupiter 9 page (in Russian) previously at the KMZ Archive website (http://www.zenitcamera.com)] in December 2008.
- | Jupiter 9 page at Sovietcams.com
- 1949 Soviet lens catalogue, also previously shown at the KMZ Archive.
- Soviet 35 mm SLR lenses at Nathan Dayton's Communist Cameras site.
- Kiev SLR cameras at Communist Cameras.
- |Soviets' Cameras page on Jupiter 9 for Kiev
- Jupiter-9, Alfred's Camera Page