Ryuji, you're right, different lenses will react differently, due to their different chromatic abberation correction, I guess. I've got ten lenses for my 4x5, could I ever be able to find my way with those calculations ?(posted 8107 days ago)Howard, do you mean that I should be using a shorter bellows length ? Since IR is diffracted at a smaller degree than visible light, it sounds strange to me. My first guess would be to use a longer bellows, if I am not mistaken.
Rhys, I know that closing down should take care of the problem, I just want to be more accurate with my focusing and not to worry so much about using a small aperture.