Roger Eichhorn B&H just sent out this interesting discussion of how the eye works, it's f/stop, speed, etc. vs. a camera lens: http://www.bhphotovideo.com/c/find/newsLetter/The-Photographic-Eye.jsp thats a pretty good description :) though the bit: "What DPI Setting Do You Actually Need to Produce a 'Sharp' Print? According to one online estimate, a 74MP image file can produce a full-bleed 13x19" color print, which when viewed from a distance of about 20", resolves the maximum amount of detail that a normal human eye can resolve from a high-quality photographic print." cuts back to the size of the circles of confusion, determined by optimal (read:'average') viewing distance. this really depends so much on a persons eyesight. someone with 10/20 vision is going to see the world a lot differently than someone with 20/10 vision! http://www.agingeye.net/visionbasics/healthyvision.php I'm blessed with 20/10 vision (or better on a good day!) - which explains why I'm *really* fussy about enlarger lenses ;)
