Originally posted by Noisychip I think non-A and screwmount lenses will even work in Av mode, as long as you use them wide open. If you stop down at the aperture ring, all you have to do is dial in an exposure compensation of + 1 EV per stop. That way, you wont have to push the green button (which I keep forgetting all the time ...).
I feel a need to point out that we only get a maximum of +3EV, so going by your method a Takumar 50/1.4 (which will tend to overexpose wide open to begin with, but will behave properly even slightly stopped down) could only be used thus:
f1.4..... +0
f2........ +1
f2.8..... +2
f4........ +3
and could not be used stopped down past f4. Forgive my bluntness, but that is ridiculous. And it would result in horribly overexposed photos.