This is about the relationship between the subject luminance range, camera exposure, and sensitometric exposure. I'm working on something that will support my answer to your question. The range above the metered exposure point is approximately 0.92 logs and the range below is 1.28 logs (not including flare).
Originally Posted by Bill Burk
It works something like in this example. The ranges have been rounded to simplify the example. Note where Hm falls compared to the shadow exposure and remember this is the exposure for a 125 speed film - Hm = 0.0064 lxs Hg = 0.064 lxs.
125 speed exposure points.jpg
For reference, here are the sensitometric exposures for a 0.00 to 3.0 density step tablet exposed at 2.048 lxs.
Sensitometric exposure for 125 speed.jpg
Last edited by Stephen Benskin; 05-11-2013 at 11:26 PM. Click to view previous post history.