PT/PD Exposure Scale

I recently helped a friend do a PDN calibration for his favorite mix of PT/PD
that I thought was quite unique—at least I had not seen anything like it
before. After determining his Standard Printing Time for Pictorico OHP film, he
printed a 31-step tablet *through* the Pictorico and achieved 29 steps or Log
2.9 exposure scale. There was separation between steps 1 & 2 in the shadows and
step 29 was paper white. We were then able to determine a Standard Color
Density to match this and printed a Tonal Palette and derived a custom curve for
this mix.

The curve is quite interesting in that it shows the affect of such a long
exposure scale on the Process Adjustment Curve for a digital negative. I'm not
suggesting that you should use this curve at all—it wouldn't work for anyone
else. It does however show how the curve is minimized by increasing the
exposure scale of a process mix.

To see the curve, go to: Mark I. Nelson Photograph Miscellaneous and click on
the thumbnail.

Happy Monday!
Mark Nelson
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Received on Mon Feb 28 15:49:40 2005