>
>Mark writes:
>
>50-100 lp/mm is typical for _on-film_ resolution. Aerial resolution,
>which could be measured by focusing the lens on a resolution target
>and looking at the back of hte lens with a microscope and focusing
>the microscoe on the aerial image produced by the lens, is always
>much higher. Today's optics for 35mm have aerial resolution
>well past 100 lp/mm. It is film that limits them to 50-100 lp/mm,
>not diffraction (up to f/11). Even if you had a lens with a
>500 lp/mm aerial resolution, it probably would only resolve around
>150 lp/mm on film, if even that.
>
>The diffraction limits are limits on the aerial resolution, not the
>on-film resolution.
I hadn't heard of this before.
If you are limited by the film to be about 100 lp/mm resolution when
in fact most 35mm lenses are far above this, then why are ANY lenses
quoted in having less than 100 lp/mm resolution. Look at some of
the numbers in the web pages linked to Lee Hawkins web site. Some
lenses, wide open, are down around 50 lp/mm. This doesn't seem to
make sense.
Mark H.
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