Judy
The Zone system was of course nothing new in that people had been altering
exposure and development to change the characteristics of the negative.
It simply provides a relatively simple way of examining the scene at the
time of exposure and predicting the effects of changes in exposure and
development on the final print.
Peter Marshall
Fixing Shadows and elsewhere:
http://faraday.clas.virginia.edu/cgi-uva/cgiwrap/~ds8s/Niepce/peter-m.cgi