My impression of Pentax lenses is that, since the A (or mebbe the F) days, they've been dumbing down. The glass just ain't what it used to be, apparently. I've been happy with the older stuff, in general, though.
Joseph Tainter wrote:
"Would you say that for instance the F 135/2.8 [IF] and the FA 135/2.8 [IF] also have identical optical quality?"
According to Photodo, the F lenses often yield higher mtf values than the FA versions with the same optical formula. We do not know why this is. In a couple of instances the FA lens is apparently better.
I have considered the FA 135 f2.8. The F version, however, rates better on Photodo. Looking closely at the numbers, the main difference is that the F is sharper at f2.8. Why? Anyway, if I decide to get one, I will look for a used F 135.
Joe
