Hi--

>Bob, Hi, I'm interested in ariel photography so I need a lens
>which can easily focus to infinity, not past infinite.
>Do most lenses focus past infinity? Do most good quality
>eg. Nikon lenses focus past infinity on manual focus mode?
>I think auto focus would not work becaus e the ground would be moving
>too fast
>and therfreore manual focus would be required, and if it goes past
>infinite, it would be difficult to focus?
> bird@lidar.ists.ca (John Bird)

(My distaste for AF lenses is great...;-) For aerial work, AF
makes no sense (heck, I haven't found any other use for it , either ;-),
since the lenses often don't hit infinity correctly (or stay there)
and AF won't work well (it really often doesn't, actually...).
If you are flying low, with longer than normal fast lenses, exact infinity-focus may not be the correct focus. BTW, there is often slight infinity-focus variation in MF lenses (very close, but not exact) AND bodies. You may want to select lenses for optimum infinity performance
at f2.8-4. Very good ones are: MF 105 f2.8 macro (!), 105 f2.5, 85mm f2, 50mm f1.8 AI/AIS(both versions)/E/AF, 55 f2.8 macro, 35PC(latest), 135
f2.8 (check the lenses on the ground for correct infinity focus AND the
same focus all around the frame [with equal corner [and opposite edge] sharpness] using a distant target [if not on film, this can only be done
in the finder {not as well...} with "F"-series bodies - misalignment
is not uncommon [where the subject plane is not parallel with the
film plane]).
David Ruether