Hi,
I have a question regarding using a color head for black and white prints. My question: do you use both Yellow and Magneta filters at the same time, or if you want more contrast just use the yellow and less, instead, the Magneta? Also, can I get more contrast using Poly filters instead possibly?
You can do it either way - see the discussion on page 3 of this Ilford publication on contrast control:
https://www.ilfordphoto.com/amfile/f.../product/1872/
Depending on the paper and the filter set you're using, a separate filter set may enable you to get a bit more contrast at the high end than your color head's built-in filters.
Different colorheads have different upper ends to their filtration. Most "top-out" at 200 units on all three colors, but not all of them.
Some might say, you can fine-tune colorhead filtration, which is true, but I've never had a need for that.
Also, it's best to test for correct exposure with colorheads and filtration changes -- of course that's a good idea with poly filters too. I learned through simple testing that the manufacturers' suggestions are not 100% accurate.
The instructions for your color head will probably have a table detailing VC filter settings for B & W printing.
For my Beseler Dichro 45S it shows only YELLOW or MAGENTA for the Ilford Multigrade filters, but it shows COMBINATIONS of YELLOW & MAGENTA for the Kodak Polycontrast filters.
Unless you want an amount of neutral density in order to slow down an exposure, there is no reason to use Y and M at the same time. Here the reason: A YMC subtractive colorhead uses "white light" (slightly yellowish due to the bulbs involved), and then filters out a certain amount of the complementary color, depending on the strength of the setting. Yellow on the dial with progressively filter out blue, and therefore decreases the paper contrast, while magenta on the dial will filter out a certain amount of the green light, and result in contrast
increase. But at anything less than the highest settings, a degree of all wavelengths will get through.
You really don't need to pay any attention to what does or does not correspond to Ilford or Kodak VC sheet filters. It's irrelevant. Besides, Kodak Polycontrast is as dead as a Dodo bird. All you need to know is that magenta light increases contrast, and does so to the degree you increase the M setting, while Y light does just the opposite, and decreases contrast to the extent you dial the Y setting higher.
If you can't get an extreme of contrast either direction, even at the highest setting either way, then you can use either a dark green 58 glass filter on the lens for even lower contrast, or a 47 blue filter for maximum high contrast. But that's kinda the nuclear option.
It's useful to look at the paper data sheets as required filtration for a given grade varies across papers, sometimes even within brands.Originally Posted by Axelwik
Why do "grades" even need to be factored into the equation? That's like ordering dentures for extinct dinosaurs. Just complicates a simple problem. VC papers provide a continuum, which varies not only brand to brand, but even developer to developer.
They don't. Once you've worked with a given color head and a given paper/developer combination for a bit, you get a sense of what different M and Y settings do with your negatives, and that becomes your basis for choosing a filtration starting point for a negative. Grade specifications are different across manufacturers, papers and filter sets anyway, so it generally doesn't make sense to get hung up on what exact grade a color head setting is supposed to be achieving.
If you are using Multigrade paper, there is a chart for each enlarger type that tells you what settings for each contrast grade. There is a chart that adds density to the filter pack so you don’t need to adjust exposure when you change grade. The instruction sheet is available on the ilford website that you can download. This will give a good starting point.
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