Whoops, sorry my bad you're completely correct. Not enough coffee yet. What I meant is that ultimately a small shift in the rear shouldn't result in massive offness (subject to lens design of course) but a change in some optical aspect that usually ends up being compensated for by literally focusing the lens.
Originally Posted by E. von Hoegh
Stop worrying about grain, resolution, sharpness, and everything else that doesn't have a damn thing to do with substance.