[pure-silver] Re: Contrast grades
- From: "Claudio Bonavolta" <claudio@xxxxxxxxxxxx>
- To: pure-silver@xxxxxxxxxxxxx
- Date: Fri, 26 Jul 2013 20:34:38 +0200
Usually the specs give two numbers:
- ISO(P) - speed of the paper (no link with film speed ISOs)
- ISO(R) - contrast of the paper
Example below on page 2:
[http://www.ilfordphoto.com/Webfiles/20135221310281826.pdf](http://www.ilfordphoto.com/Webfiles/20135221310281826.pdf)
Said that, the grade numbers usually don't match from a brand to another.
Even if the ISO(R) number do match, the result may appear different.
Claudio Bonavolta
www.bonavolta.ch
*Le 26 juillet 2013 20:09, Sauerwald Mark a écrit: *> I understand how a
higher number for the contrast of a paper, or for variable contrast papers,
using a filter for the higher grade results in a higher contrast print. What
I am wondering is if there is any objective measure of what a contrast grade of
'N' is. If I use contrast grade 3 paper from one manufacturer, will I see the
same contrast as if I use grade 3 from another manufacturer? I imagine that
plotting the exposure vs density you would be able to measure the slope of the
curve at some point (perhaps when the density is at a predefined level,) and
the steeper the slope, the greater the contrast - and you could define the
contrast grades by defining this gradient for each grade has that been done?
If so, where is it documented? Mark
Other related posts:
