I remember reading somewhere that there's some sort of hack to gain Iris control with the Canon FD lenses. I can't find the thread its in. Does anyone have any idea how to do this?
This works on newer Nikons as well, by the way. I tried it on my 18-55 f/3.5-5.6 and 55-200 f/4-5.6 DX lenses. It means you default to shooting wide open, but since the glass is already so slow, it's not really an issue.