Quote Originally Posted by CPorter View Post
I don't bother with CI myself, I just compare the curves, I find that to be most illuminating and the most straight forward.
I don't have your experience of reading the curves, as I have only started sensitometric analysis of my materials. I have no doubt, however, that you are right. Re-reading BTZS, plus many good points raised on this, and on other related threads, have opened my eyes to the holistic nature of the tone reproduction cycle. It is clear to me that subtleties of the cycle cannot be summarised by just a single gradient number.

Nonetheless, I found it necessary to figure out developing times for my N, N-1, and N+1 negatives. I found that knowing an aim DR, as described by BTZS, or a gradient, G-bar, or CI, all are perhaps crude, but practical ways to summarise the requirements of the printing process for the film development output. This was my main goal of this calibration exercise.