My reference is an article entitled "Really Right Stuff for Photography
Afield". I am uncertain of the original author, my copy is froma person
named Dave Swager. Anyways, following the discussion on lens resolution in
relation to aperture, the article states:
"However, film resolution has also been shown to vary appreciably with
aperture, and the resolving power is always highest when the light source
area is minimized, to retard dispersion. This presents a troublesome
dichotomy: Best lens resolution is achieved when shooting wide open, but the
best film resolution is a f/22 (or smaller)! Obviously, compromise is the
answer, and that is probably why most of the published ("on film") lens test
for top quality glass indicate that f/8 is optimum, with f/5.6 and f/11 not
far behind. So-what you learned about "optimum aperture" wasn't all
wrong-but blame was certainly misplaced."
The balance of the article takes an academic turn and deals with some of the
math behind these assertions. I will be happy to provide hardcopy of the
article to the interested reader.
expressionless,
John P
______________________________________
Joseph Albert <jalbert@xxxxxxx> asked
>
>I've never heard that film resolution varies with lens aperture, and it
>is rather counter-intuitive-- might you be able to explain why this
>would be?
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