Hi--

>This is not sufficient warning, I believe. Some non-AI lenses have
>plastic and metallic parts protruding out of the rear end. So there is
>an additional danger of ruining the electrical contact as well as the
>mirror----even if the lens is AI'd by making the rear end of the
>aperture ring flushed with the mount. I didn't mean those non-AI lenses
>that require mirror lock up; in this case, it is obvious that they can't
>be used. The F4 manual says that the 28mm f/3.5 non-AI cannot be used
>with it, and I believe the reason is that the 28mm f/3.5 does have some
>parts protruding out of the rear of the lens---although the 28mm f/3.5
>does not require mirror lock-up on the older Nikon bodies.
> Albert Ma ma@bu.edu

This is good information that should be added to the thread. I was
unaware of any older-lens incompatibility other than the AI issue.
I would limit the warning, though, to the specific len(s) listed
in the F4 manual, since most are compatible...
David Ruether