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Old September 25th 07, 12:48 AM posted to rec.photo.digital.slr-systems
John Sheehy
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Posts: 878
Default Less lens contrast to cope with narrow DR of camera?

RichA wrote in news:1190291390.186946.120710@
22g2000hsm.googlegroups.com:

http://forums.dpreview.com/forums/re...hread=24340033


Reducing contrast in the optics is like under-exposing, only with more
noise in the shadows, once you have re-normalized the tones.

Basically, what is happening is that some of the light is not forming a
sharp image on the focal plane, but is scattering randomly. This means
that black becomes brighter, and even colored. That means more shot noise
for the lower tonal ranges than if you had used a high-contrast lens, even
if you under-exposed a bit.

The apparent increase in exposure latitude is an illusion. Under-exposing
with a high-contrast lens in such a way as to give the same exposure as the
low-contrast image minus the false "black" leaves less noise in the
shadows, and leaves more room for highlights.

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John P Sheehy