{"overview":"The Jupiter-12 is a Soviet 35mm f\/2.8 wide-angle rangefinder lens produced from the post-war era onwards, derived from the pre-war Zeiss Biogon design. It was made in Contax\/Kiev bayonet and Leica M39 screw-mount versions and is characterised by a deeply protruding rear element that sits close to the film plane.","market_narrative":"At recent UK auction, hammer prices for the Jupiter-12 have ranged from £25 to £60, with a median sitting around £40 — these are wholesale saleroom results rather than dealer retail figures. As of 2026, clean M39 copies tend to sell for the upper end of that band, while tatty or haze-affected Kiev-mount examples are what a Jupiter-12 is worth at the lower £25–£35 level. The price spread is narrow because supply is plentiful and the lens has never carried collector premiums comparable to its Zeiss ancestor.","buying_guide":"Inspect the front and rear groups carefully for fungus and haze, both of which are common on Soviet glass of this age, and check the protruding rear element for coating scratches caused by careless storage. Work the aperture ring through every stop to confirm the blades are dry and snap cleanly, since oil migration is a frequent fault, and turn the focus helicoid end-to-end looking for stiffness, grittiness or a dry feel that indicates the grease has hardened. Confirm the mount matches your camera — the rear element can foul shutters and meter cells on some later bodies, so test-fit before buying.","specs":"Wide-angle rangefinder lens of 35mm focal length and f\/2.8 maximum aperture, supplied in Contax\/Kiev bayonet or Leica Thread Mount (M39).","faq":[{"q":"How much does a Jupiter-12 35mm f\/2.8 sell for today?","a":"UK auction hammer prices over the past two years have run between £25 and £60, with most usable copies changing hands at around £35–£45."},{"q":"What is a Jupiter-12 worth in clean condition?","a":"A clean, haze-free example with smooth focus and dry aperture blades tends to reach the top of the observed range, around £60 at the hammer, based on recent sales."},{"q":"Does the mount version affect the price?","a":"The sales data does not show a consistent premium between Kiev-bayonet and M39 copies; both versions appear across the full £25–£60 band, so condition matters more than mount for current value."},{"q":"Will a Jupiter-12 fit any Leica or Contax-mount camera?","a":"The rear element protrudes significantly into the body, which can interfere with shutter curtains or light meters on some cameras, so a test fit is recommended before committing to a purchase."}],"confidence":62,"reasoning":"Eleven sales records give a reliable price picture, but no SPECS data was provided, so technical detail is limited to widely-known public information about the lens."}