SC same glass as Leica Mt, in NRF mount
SC same glass as Leica Mt, in NRF mount
The Voigtlander SC lenses are the same glass as their Voigtlander Leica mount counterparts, the SC 21/4, 25/4, 28/3.5, 35/2.5 and S 50/3.5 Heliar in internal mount, 50/1.5, and 85/3.5. All in external bayonet Nikon rangefinder mount except the 50/3.5, and all RF coupled. The SL 12/5.6 and SL 15/4.5 can also be used on NRF or Contax bodies, with the appropriate adapters.
So the SC 25/4 is RF coupled while the Leica version is not.
The SC 21 and 25 VF are dedicated to Nikon RF bodies, with different offsets than the Leica versions.
The SC lenses are made for Nikon Rangefinder bodies, which means slightly different from the Contax/Kiev bodies. for diff see
http://cameraquest.com/NRF-Contax.htm
real world however, the difference was considered so slight for the wide angles that they are taken to be interchangeable.
3 SC 35/1.2 prototoypes were also made. Tom A has one, Mr. K has one, and I have one. Will eventually put up pics.
Stephen