Originally posted by WPRESTO I'll make a few general observations. 1) optical design can be optimized for certain distances
yuh - just to go on from that point - I don't have a modern 100mm f/2,8, but on my F version, the last measured distance before infinity is only 3m - there is very little focusing throw between 3m and infinity, so perfect accuracy, either by hand or AF would be hard to achieve.
Also, it has to be noted that infinity itself isn't that sharp - the further you get from the lens, the more atmosphere gets in the way