> Pentax K register distance is 45.46mm > Canon FD register distance is 42mm > > This means that to alter an FD lens to fit a K mount camera (without > using an adapter containing an optical element to correct for infinity > focus) you would have to remove over 3 and a half mil from the back of > the FD lens flange. If you're going to use a 42mm threaded adapter, then > add the thickness of the adapter to that. Might be problems in that > there's not enough room on the back of the FD lens before problems start > in terms of aperture ring etc. You may or may not have problems with the > rear element of the lens not clearing the mirror. I don't have an FD to > look at, but where there's a will, there's a way. > > I have some links on the bottom of this page that might be of further > interest: > > <http://www.cottysnaps.com/snaps/mods/details.html> > > It's a big job but as an engineering exercise, viable, if expensive. Of > course, as a hobbyist, cost is not justifiable so go to it! > Registration distance will definately be a problem for this exercise if you want to try to maintain infinity focus. Last time I handled an FD lens, the breech-lock seemed "smaller" in diameter to the K-mount flange... Maybe it could be made to fit *inside* the K-mount body by 3mm? Of course mirror clearance is a big problem, but maybe for the smaller mirrors of the APS-DSLRs it's OK?
-Cory -- ************************************************************************* * Cory Papenfuss, Ph.D., PPSEL-IA * * Electrical Engineering * * Virginia Polytechnic Institute and State University * ************************************************************************* -- PDML Pentax-Discuss Mail List PDML@pdml.net http://pdml.net/mailman/listinfo/pdml_pdml.net
