Originally posted by Nicolas06 If you think you need 85mm on APSC for the compressed rendering it provide, you'd need 127mm to get the same compressed rendering on FF. The 85mm shoot on FF would look like the 55mm shoot in term of perspectives. This mean that it would not change your problem a little bit.
I agree that you might have better in focus - out of focus transitions, more shaprness down to fine details and less deph of field, but none of theses is what you ask for.
The rending won't change between formats for a given lens... but I may be misunderstanding what you meant.
I'm ok with the current working distance of 50mm on APS-C, but not the distortion. Going up to 85mm on APS-C (to control distortion) I'd have to be further away from the subject to get similar framing, but that won't work as I'd have to move diagonally up and away from the subjects, and I'm already standing, in that specific case.
If I were shooting FF @ 85mm, I'd have a bunch of extra room around the subject (the bit chopped off due to the APS-C crop) so I wouldn't have to back up much (at all?) to get similar framing, and I'd be happier with the resulting look. That's assuming the minimum focus distance of the 85mm was short enough - something that I hadn't thought of before.
There are also the differences in sharpness and pop, too. Perhaps I've just spent too much time looking at oversharpened 85mm images...
I may have time about 3 weeks from now to run a test; rent a 5Dmk2 and a couple of lenses, and shoot some comparisons for myself. It may not be a blind test (to me) but I'm curious about the results now. If I'm not super impressed with the differences it would sure save me from buying a Pentax FF when I could further justify the 645Z ... snerk...