This lens uses a unique historical design to match some of the earliest Voigtlander lenses from the 19th century. The lens design has been on the market for a long time. Several different versions exist in Leica thread mount (LTM) and Nikon S mount. I believe that initially the lens came with the Bessa R2S Nikon S-mount rangefinder as a special edition and many people just used it with adapters on Leica M mount cameras.
