> Isn't it that the 52mm front thread lens (Tak Bayo) is also a the > shorter lens, making the light path less long? Not so much light > bending to go on, and the same effective aperture can be > physically less wide, in a shorter lens assembly. So I have > gathered from what I've seen over the years... A long, fat f/2.5 > and a shorter, narrower f/2.5 are essentially just different ways > of reaching the same place.
Perhaps, Keith. (I make absolutely NO claim to be any sort of an optical expert - <g>.) However, while I do understand that it might be the ~effective~ aperture that is important in the equation of max aperture in f-stops = focal length in mm / aperture in mm , I still can't get used to how an ~effective~ aperture can ever be greater than the actual physical diameter of the front objective. (As I said, though, I make NO claim to be an optical expert - <g>.) Fred
