Nicholas,Thank you for the links. The graphs you show do show that grade '00' contrast is not terribly useful. In my own printing I tend to use between grades 1 1/2 and 4 1/2. The ILFORD MULTIGRADE documentation for dual filtration gives '162Y, 0M' = grade 00 for the Kodak system (apparently includes DeVere) enlargers; '90Y, 0M' for grade 0, and this agrees with the given figure for single filtration on grade 0, i.e. 90Y. However, the given figure for single filtration grade 00 is 199Y. There is also a mis-match between grade 4 1/2 in the ILFORD documentation, 0Y, 150M (dual), 140M (single), is this because of relative difference through the contrast range, i.e. single and dual are not perfectly matched in terms of resultant contrast?
Further testing with the step wedge (DeVere 5108, dichromat head, 16 seconds, f/8, 150mm lens, 8x10" paper) @ 180Y, 160Y, 140Y, 120Y, 100Y, and 80Y show that as contrast increases with decreasing yellow filtration, differentiation between the dark tones (on the paper) is maintained while differentiation in the light tone wedges is lessened. There is also the factor of density change (when maintaining exposure settings) if starting from a lower yellow filtration pack, which may effect perception of contrast.
Tom Nicholas O. Lindan wrote:
"Tom Kershaw" <tom@xxxxxxxxxxxxxx>[is] there ... little or no practical application to using 200 units yellow, even if the ILFORD MGIV RC GLOSS paper can respond to such reduced contrast levels?You may want to look at the graph and text at the top of page 3 to see what happens with too much yellow: http://www.darkroomautomation.com/support/appnotevcworkings.pdf VC paper has no minimum contrast, but it isn't worth much after a certain point. A real-world example: http://www.darkroomautomation.com/support/mgivfbwtd72hd.jpg == Nicholas O. Lindan Cleveland Engineering Design, LLC Cleveland, Ohio 44121============================================================================================================= To unsubscribe from this list, go to www.freelists.org and logon to your account (the same e-mail address and password you set-up when you subscribed,) and unsubscribe from there.
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