Archived posting to the Leica Users Group, 1999/12/01
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]From: Mike Johnston <michaeljohnston@ameritech.net> > >>>>> > At 07:12 PM 11/30/1999 -0800, Ken Iisaka wrote: > >I concur. I have been told that Nikon designers were tempted to change the > >mount to remedy its deficiencies, namely the long distance between the > >flange and the film plane, and the diameter of the mount > > Whoever they were are wrong. I have it from the head of NPS that this is > not the case. > > Eric Welch > Carlsbad, CA > > Eric, > I don't think this is correct--I think Ken is right. Several lens > designers have told me that the diameter of the exit pupil is the third > biggest limitation on the design of fast lenses for SLRs--first if you > discount selling price and size, which are the two limiting factors that > usually beat it out. Have you ever seen a Canon 50mm f/1? It obviously > uses every millimeter of the exit pupil. and if you see the rear element of a Nikon 50/1.2, 55/1.2 and 58/1.2, every millimeter of space is used. As the mater of fact, the rear element is trimmed a little bit for one of the tabs. These rear elements are as far back as they can be placed without interference with the mirror, and there is no physical way to implement a larger exit pupil that determines the f-stop. The anecdote about the decision comes from a friend who is in the camera design group at Nikon who shall remain nameless to protect his job security.