Jupiter-8

Jupiter-8 (M39 mount). image by Michael Gatchell (Image rights)

The Jupiter-8 (sometimes marked in Cyrillic, ЮПИТЕР-8) is a 50 mm f/2 lens made by KMZ in the years after the Second World War. It is a close copy of the Zeiss Sonnar, with six elements in three groups; the Soviet Union took the design data for several Zeiss products in War reparations (equipment, and even staff, were also taken to the Soviet Union). The Sonnar had been the standard lens for the Contax, and the J-8 became the standard lens for the Kiev, the Soviet copy of it.

KMZ originally made the Jupiter-8 for the Kiev; it was made by the Arsenal factory from about 1956. KMZ also made the J-8 in an M39 screw mount for its Zorki rangefinder camera series: it first appeared on the Zorki 3 in 1953, and later was the standard lens on the Zorki 3S. Both versions of the lens appear in a 1949 lens catalogue.

GOMZ's Leningrad rangefinder of 1956-8 also came with a Jupiter-8, made by KMZ.

The J-8 was originally made with a polished aluminium barrel, though some examples exist in stainless steel. From the 1970s, the lens was made in a black finish (the barrel is still aluminium).

The lens takes 40.5mm filters. The aperture ring lacks click stops: these were introduced in the Jupiter-8M version in Contax rangefinder mount.

Optical formula, from OPAL database

Radii	Thickness	Height	Glass
26.42	4.2	14.50	TK16
91.83	0.25	14.10
17.378	4.0	12.10	TK21
34.67	3.5	11.40	LK8
-394.5	1	10.45	TF2
11.83	3.75	8.40
stop	1.25	8.35
-91.83	2.2	8.10	TK21
-45		10.15

Links

• A Jupiter-8 page at Alfred's Camera Page
• Flickr Smaller Jupiter-8 group
• Servicing Jupiter 8 lenses, by Kim Coxon, at Pentax Manuals