I also do Complete compatibility together original Zorki rangefinder Contax Inner Helicoid No depth of field engravings No bayonet lock.... But interesting -No outer bayonet! Regards
The plate is self made, most likely milled from billet. And TSVVS has only served as a model. Eg the cone on the plate is different,it is easy to compare as I have my TSVVS here.
Lens mount is from a very late Contax (series O). Mount shows the 'blue dot' (near '6').
Absolutely right. This Sonnar belongs to a wartime batch of 5000 2/5cm Sonnars in bayonet mount. Many of them were originally mounted on Contaxes II and III, series M and O. The others were often converted into screw mounts: for example one on a Fed Arsenal, another on a Red Flag...