In article <541jel$cl2@cello.hpl.hp.com>, jacobson@cello.hpl.hp.com says...
>In article <5418la$lt8@newsstand.cit.cornell.edu>,
>Bob Neuman wrote:

>>If you use a good model 75-80mm lens for 35mm (with appropriate condenser
>>setup, if using condensers) made by Schneider, Nikon, Rodenstock, etc.,
>>the results should be about equally excellent at f8-11 with any of them.
>>Using a longer than normal lens provides the benefits of more even
>>illumination, more even sharpness, more space for dodging/burning
>>operations, and maybe a bit less of a problem with film flatness...
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>Any unsharpness from film unflatness is, to the first order, dependent
>only on magnification and effective f-stop. The focal length does not
>matter. Maybe you were thinking of some other effect from film
>unflatness.

Ah, this is where we came in, so long ago....;-)
(I did include a "maybe" and a "..." in the above, knowing that you
were probably lurking in the background ready to once again pounce
on this! ;-) And we covered this same question, later, in a different form....;-) Your math ability is, uh, "infinitely" better than mine,
and the above and the idea put forth later in this thread does convince
me (maybe ;-) that you are right when the magnification and effective
f-stop do not change (unlike with wide vs tele on a camera with a given
amount of defocus.....;-). Bravo!
Uh, Hope This Helps...;-)