iq comparison question

is there any difference in iq between 1, Pentax A 70-210 f4 and
2, Pentax F 70-210 f4-5.6

From experience, very little, they're both very good performers. The "A" has the advantage of constant f/4 aperture and of course you have AF with the "F" and it's rather more compact, with 49mm filter size as opposed to 58mm with the "A" Both are solidly constructed, the "A" is push/pull zoom and the "F" has a zoom ring, so it's probably all down to personal preference. I sometimes use the F 70-210 f4-5.6 to replace my FA 135/2.8 in my main bag, it's roughly the same size and has the same lens case.

Hope this helps,

John