>Nikon has not had a true mirror lock up feature which allowed >shooting deep rear element lenses, like Laddie mentioned, >since the F2 and maybe some Nikkormats. The true lockup would >keep the mirror up over many exposures until you physically >released it. Nikon never made a true mirror lockup on a >digital body except when sensor cleaning. > >Len
Nikon F3, F4, and F5 all have true mirror lockup and can be used with the old deep rear element lenses.