PT0805. Seems to be an earliest version of "Jupiter-12" lens. Under initial name "BK-35" ("Biogon Kransogorsk"). Very few lenses released by KMZ in 1947-1948. These first samples are totally assembled from Zeiss (Germany) optical glasses. Focal length - 3.5 cm, aperture range f2.8 - f22. Focusing range from 0.9 m to infinity. Number of elements/groups: 6/4.  Angular field - 63º. Zorki (M39) mount. An earliest so far known lens has s/n #000274 1948 (SovietCams).

PT0805 - BK  #000274.

PT0810. 2nd generation of these beautiful lenses. Almost identical to its predecessor "BK-35", but under name "BK Zorki" already. Very limited batch of these lenses released by KMZ in 1949-1950. Partially or totally assembled from Zeiss (Germany) optical glasses. An earliest so far known lens has s/n #4902114 (C.Asquini coll.).

PT0810 - BK Zorki  #4902338.

PT0815. Lens identical to PT0810, but under regular name "Jupiter-12" already (see comparison picture below). Very limited batch of these lenses released by KMZ in 1950-1952. This version should be totally assembled from soviet optical glasses already, but I stil doubt about the reliability of this information. An earliest so far known lens has s/n #5000286 (D.Krivosheev coll.).

PT0815 - Jupiter-12  #5102071.

PT0820. The regular and last version of Jupiter-12 lens, released by KMZ in 1952-1961.  Signally changed body design, modified diaphragm setting ring. New version is taller and wider in 3 mm (see comparison picture below). Quite common to find nowadays.

  

  

PT0820 - Jupiter-12  #5703497.

PT0822. Very rare to find lens. Totally black body with additional "MADE IN USSR" markings on the side-plate. Very limited quantity released by KMZ in 1960-1961 (?). An only so far known lens has s/n #6007060 (SovietCams).

PT0822 - Jupiter-12  #6007060.

PT0825. Lens identical to PT0820, but released by LZOS {"Lutkarinskij Zavod Opticheskogo Stekla"). White body. Name markings in Cyrillic characters. Some cameras have an additional "MADE IN USSR" engravings on body. No otherwise different. Quite common to find nowadays.

PT0830. Less common to find lens, released by ARSENAL Zavod (Ukraine). White body. Tightening ring around the rear element. No otherwise different from PT0825. Not discounting a possibility of beeing fake!

PT0825 - Jupiter-12  #5800284.

PT0833. Lens by LZOS identical to PT0825, but with export name markings already. Very good quality, bright-finish body. An additional "MADE IN USSR" engravings on body. Less common to find nowadays.

PT0833 - Jupiter-12  #6310981.

PT0835. Lens by LZOS identical to PT0833, but with black body finish since 1971. Name markings in Roman characters. Some lenses have an additional "MADE IN USSR" engravings on body (few different styles, see picture below). Very popular to find nowadays at the reasonable prices. Some lenses have slightly different body design (known sample has s/n #7302778, SovietCams).

 

PT0835 - Jupiter-12  #8303289.

PT0840. Prototype lens by LZOS, released in 1971 only.  Signally redesigned lens body with new aperture control (see comparison picture  below). An earliest so far known lens has s/n 710004 (SovietCams).

 PT0840 - prototype Jupiter-12  #710004.