Hi--

>> All Nikkor lenses (except the 21mm f4 non-retrofocus) will fit the
>> F3, but...

>Why does the 21 F4 not fit the F3? I know th 21 F4 [non-]retro requires
>mirror up operation, but what doesn't fit? Does in interfear with
>the finder (e.g., like the non-retro fish-eyes on the F-FTN?).
>mk stenstrom

The 21mm requires a small bar in the camera bayonette to keep the
lens from rotating while being mounted (the rear element top is cut
flat to clear the mirror bottom, to allow having a large rear
element - but it cannot turn in the opening without striking the back
of the folded mirror). F, F2, and Nikkormat cameras have the bar
(though, for some reason, the lens will not fit on the Nikkormat!).