VinceC
Veteran
I can see a minor but noticeable focus shift when using lenses wide open at closest focus on the wrong body (Jupiter 12 on Nikon RF and Nikon 35 2.5 or 1.8 on a Kiev). I do a lot of shooting wide open at 3 or 4 feet (1 meter) so it's a problem for me and I don't often mix the 35mm lenses between systems. If you shoot stopped down or focused 6 or 7 feet to infinity, you probably would never notice it (at infinity, the lenses are in focus for either system -- the error creeps in as you begin to focus closer).