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Re: (Lens Contrast..Sam the 3d Hacker asks?) digest 1562


  • From: P3D Bob Howard <bobh@xxxxxxxxxxxxxxxxxxxx>
  • Subject: Re: (Lens Contrast..Sam the 3d Hacker asks?) digest 1562
  • Date: Thu, 26 Sep 1996 11:17:03 -0700

RE: Sam mentions 'better shadow detail' in flarey lens and asks if a
filter could lower contrast in hot modern lens?

The high contrast in modern lenses is due to the choice of focus point
in the airy disk favoring larger core and less 'flare rings' and cannot
be changed. BUT the flare factor and shadow detail is true and this was
the big change coating made. Prewar uncoated lenses, particularly fast
ones six element Biotar (Gauss) types had bad flare wide open and this
fogging of the film increased apparent shadow detail and may have also
broken down photon barrier as flashing does. So it was soon noted that
uncoated lenses were sometimes better for low light photography.
A diffussion filter which is much like a scratched lens surface,
scatters light, but as it affects highlights different than shadows it
gives a glow to bright areas. I suppose the best answer is a fast low
contrast film? BobH


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