My 300 f4 gives me a ERR 01 message in TV mode and over exposes by almost 2 stops in AV.In M I have to compensate by almost 2 stops as well.I cleaned the contacts on the lens using a dry cloth and my 70-200
still works properly so it's not the body.
Can anybody tell me whats wrong in the lens and is it an expensive fix?
Thanks Del

