Please explain this. I have an Ikon. Are you saying that the issues being discussed about 'optimization' and focus shift don't apply when using the Ikon? Because of the wider RF baseline? Are all of the people who are talking about limiting aperture choice based on which aperture the lens is optimized for... are they all shooting it with a Leica or Hexar?
I probably would have bought the C-Sonnar instead of the Summicron i have now, except for the focus shift stuff. I'm not really interested in fudging my way around with it, as i use too many different kinds of equipment, and i'm sure i'd forget to NOT focus on the eye when i wanted the eye in focus at 1.5 or whatever....
By the way... my first M-mount lens was an original Zeiss 50mm 1.5 Sonnar, and with an M7, i never recalled having any focus shift problems.....