{"overview":"The Contax 21mm f\/2.8 Carl Zeiss T* Biogon is an ultra-wide prime built for the Contax G rangefinder system, pairing the Biogon optical layout with Zeiss T* multi-coating. Introduced in the 1990s as part of the autofocus G-series line-up, it was designed to deliver rectilinear wide-angle coverage in a compact body suited to reportage and landscape work on 35mm film.","market_narrative":"At recent UK auction the 21mm f\/2.8 Biogon has shown a wide spread: hammer results in our records run from £210 in November 2025 up to £480 from an earlier 2011 sale, with a two-sale median of £345. As of 2026 the more recent hammer price is the better guide to what a clean copy sells for today at saleroom level, while exceptional examples with the matching 21mm viewfinder and original box can push the value higher. Buyers should remember these are wholesale hammer figures; retail and dealer asking prices typically sit above this band.","buying_guide":"Inspect the front and rear elements under a bright light for fungus, haze and cleaning marks, since the deep rear group sits close to the film plane and can trap moisture. Check the aperture blades for oil, confirm the focus ring turns smoothly without grit, and look for coating scratches or early signs of separation at cemented groups. Confirm the lens couples correctly with a G1 or G2 body and that the electronic contacts are clean, as autofocus faults on the G mount can be costly to repair.","specs":"Key specifications from the supplied data: 21mm focal length, f\/2.8 maximum aperture, Carl Zeiss Biogon optical design with T* multi-coating, built for the Contax G rangefinder mount.","faq":[{"q":"How much is a Contax 21mm f\/2.8 Carl Zeiss T* Biogon worth at UK auction?","a":"Based on our UK hammer records the lens has sold between £210 and £480, giving a two-sale median around £345, with the most recent 2025 result at the lower end of that range."},{"q":"What is a Contax 21mm Biogon worth compared with retail prices?","a":"The figures quoted here are auction hammer results — wholesale levels before commission — so dealer retail prices for a clean, tested copy typically sit above the saleroom price."},{"q":"How much does a Contax G 21mm Biogon sell for with the viewfinder?","a":"Our dataset does not separate lens-only from kit sales, but complete sets with the dedicated 21mm external finder and original box generally command a premium over the recorded hammer prices."},{"q":"Is the Contax 21mm Biogon a good value ultra-wide for the G system?","a":"For buyers already invested in the Contax G mount it remains the native ultra-wide option, and recent hammer prices near £210 make it one of the more accessible Zeiss Biogon designs on the used market."}],"confidence":40,"reasoning":"Only two sales records are supplied and one is from 2011, while SPECS and FACTS are empty, so confidence is capped below 50 per rule 8."}