I have a Canon FD 135mm 1:3.5 lens. I noticed when I had the lens detached from the camera and was looking at the front of the lens, that as I turned the aperture ring from f22 down to 3.5 the aperture hole would continually get bigger until around f8, then would no longer widen after that point. Does this mean that the lens is not functioning correctly? Could the lens aperture be stuck and not open beyond this point?

-- George Fries III (gfriesiii@innernet.net), October 05, 1998

Answers

When an FD lens is unmounted, the aperture either opens fully (with BL lenses) or opens to f5.6 (with the newer FDn lenses). This is done in order to make the coupling between lens and body possible. The lens aperture lever (the one on the side) has to be above the lever from the body when you attach the lens. When you mount the lens, the diaphragm is released, and with the lens stopped down, closes to the desired aperture.

John

-- John (jmllal@spacestar.net), October 05, 1998.