<<I enjoyed this discussion, which (at least to me;-)) claryfied things.
Would
those who took part in it agree to the consensus: "Sensitometry is a perfect
tool but not the key...?"
Klaus Pollmeier >>
To which I would only want to add "but it does stop you saying all sorts of
things which cannot be substantiated!"
Peter Marshall
Fixing Shadows and elsewhere:
http://faraday.clas.virginia.edu/cgi-uva/cgiwrap/~ds8s/Niepce/peter-m.cgi