Quote Originally Posted by jdef
... make your test strips without a filter, which will equate to a grade 2 contrast,...
Quite a while ago, I first tried Variable Contrast paper, and was "*totally** dissatisfied with the results. That led me to investigate the character of the unfiltered light from the enlarger *without* any filtration. I reasoned that there had to be some difference - the color temperature from the "old" Omega B22, with the PH212 (?? - from memory - could be far "off") had to be something like ~ 2800 - 3000K; where the halogen in the Omega D5500 would be higher ~ 3500K, or so.

I tried the Ilford MultiGrade filters - and the results were *much* better. - a "2 1/2" filter would produce a "2 1/2" grade print.
So - to a comparison of the unfltered light and the light with filter in place...

I found the combination of dichroic color filtration that would produce light of the same color value as that using the gelatin "2 1/2 Grade" Ilford filter: Cyan= 00; Magenta=58; Yellow= 12.

I went through ALL the Ilford filters, and recorded the values for each; produced a line graph, and am now able to determine (caveat: the data depends on interpolation - ) the settings that would be theoretically correct for a "Grade 2.75" - or any "hardness" value.

Incidentally - those figures do NOT match the data given by Ilford in the Data Sheets included with the paper: Even there, they specify different settings for "single" and "multiple" dichro head settings.

So the "old" system - "Test, test, test ... and when you think you've done enough - test some more", is the way to go.