Great thread and fascinating to hear all the opinions, insights etc. Andrew/Andy - I'm currently building myself a set of C/Y Zeiss and to date have the 21mm, 28 (2.8), 35 (2.8), 50 (1.4) and the 28-85mm zoom. I may get the the 85mm (1.4) then I think I'm probably done. I currently have a GH2 and have a Metabones C/Y-M4/3 Speedbooster but want to use the lenses with other cameras (i.e. an A7S in future). I'm considering getting them modded to Canon EF mount: not so much because I'm planning to buy a Canon camera, but more because C/Y is a dead mount now (unless Kyocera resurrect it!) and EF mount would allow them to be mounted natively on a number of cameras, plus adapted to others. Good move, or no? I think I read somewhere that Leitax-modded Contax Zeiss lenses aren't compatible with Speedboosters: is this true?