A subject which was briefly touched on in the Pentax 645 review was the problem of focusing at distances which are almost, but not quite, at infinity. In the article this referred to AF lenses, but I am having trouble with this very problem using my old CZ MF lenses.
The issue arises principally with the 150mm Sonnar. If my subject is say 200 to 400 feet away from me, and I set the lens focus to infinity, although DOF at f11 or f16 should theoretically cover things, when I view the result on the PC screen the subject is noticeably soft, made worse by the fact that the background is pin-sharp. However, when I view the scene through the 4X magnifier on my camera, I simply can’t see the difference in focus between the subject and the background no matter how careful I am. And the scale on the lens stops at 100 feet, beyond which there is only a tiny rotation to the end stop at infinity, so guessing the distance and setting it on the scale is kind of hit-or-miss.
This is really annoying me, because I have now (with care and a lot of practice) just about cracked all my other focus issues and very rarely miss. Any advice you chaps might have would be most welcome.
John