In article <19970626042901.AAA29874@ladder02.news.aol.com>, edmall@aol.com says...

>Generally, it's midway in the range of the lens. It may be important to
>try to shoot at f8 or f11 or f5.6 if you're going to blow it up to 11x14
>or larger. However, sharpness is only one aspect of the picture. All
>those other apertures are there to enable you to control depth of field.
>And that's the trade off.

Well put! (Maybe that "two-stops-down-from-wide-open" nonsense will
go away soon... - in all my [too] extensive lens checking experience,
the vast majority of [good] lenses peaked in the center around f8,
regardless of the focal-length and speed...)
Hope This Helps
(David Ruether - http://www.fcinet.com/ruether )