Well I have read Dr. Atkins' article a few times and must admit to simply
being baffled. I have several hours of intense searching only to find
"dispersion" purely as a lens property, not at all applicable to film. The
closest similarity of such a behavior in today's emulsions is "halation".
But these are characteristics with very different origins. I mistakenly
thought the two were synonyms - wrong!
What I find kinda funny is every source I have uncovered has the same
conclusion - system resolution is best around 3 stops from wide open, just
lots of different reasons why. Less and the image is not as sharp, more and
the image is not as sharp. f/8 - or thereabouts - is universally agreed to
be the sweet spot for best resolution. As for me and my OM - I'll be happy
to know it works, load 'em up with the film du jour, and have a good time
;-)
Since the math of Third-Order Aberrations is more than I care to wrestle
with, I'll point the interested reader to:
http://www.jmlopt.com/third_order.html?L+jml. The dispersion discussion
begins just after figure 10.
John P
and thanks for the nudge to dig a little deeper into this, Paul.
______________________________________
there is no "never" - just long periods of "not yet".
Paul D. Farrar <farrar@xxxxxxxxxxxx> pointed out:
>At 08:47 PM 9/28/98 -0700, John P wrote:
>>>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:
>
>There are other opinions on that article. For example Bob Atkins, who
>usually knows what he's talking about:
>
>http://bobatkins.photo.net/info/rrs.html
>
>I haven't gone through it in detail, so I don't have an opinion yet.
>I do object to the way the word "dispersion" is used, since that has an
>accepted (and different) meaning in optics and othe wave mechanics.
>
>Paul Farrar
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