I have two adaptors namely Pentacon Six to Mamiya 645 and Pentacon Six to Canon FD. I use the P6/Mamiya adaptor less these days because I have a nice range of Mamiya lenses that cover my needs. I got the P6/Canon with a view to doing some bird photograpy because I have a 300mm F4 Sonnar and a 180mm f2.8 Sonnar.