This is probably a very silly question.... What determines the maximum coverage of a particular lens? Is it design of the lens? Is it focal length of the lens? Is it the distance between the lens and the film? The reason I ask is that I am starting to collect a bit of junk camera body and lens... from 35mm to MF to enlarger lens. If I wanted to play with these and say, make a panorama shooter, projecting to 120 film, how should I logically approach the lens selection?