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brian steinberger
27-Oct-2006, 21:46
I'm in need of some neutral density when printing. I'm using Kentmere paper which is a fast paper to start with. I'm not printing large (8x10 and some 11x14). And even though I'm stopping my lens down to f/16, My exposure times are around 10 seconds. Too short for me to dodge and do other things.

I have a Beseler 45S color dichro head, and I heard once that you can use the cyan filter as a ND filter. Is this true? And, also, whether or not it is true, I know I can use ND filters, but will it affect image quality under the lens? How do I put one above the lens?

Thanks for any and all help!

Donald Miller
27-Oct-2006, 22:13
While magenta will serve to increase contrast and yellow will serve to reduce contrast, the combination of cyan, magenta, and yellow produce neutral density.

For instance if you are printing with 60 of magenta and 40 of yellow and you add 40 units of cyan you will have effectively added 40 ND to the filter pack.

robc
28-Oct-2006, 07:05
It's a myth that Cyan has no effect on contrast in a B&W print. It does. I have tested it. Not surprising really because the cut off wavelength sensitivity in the paper is not sharp. If it were people wouldn't have nearly as many problems with safe lights.

However, if you are always using say 50 units of cyan on a praticular paper, then when you adjust yellow and magenta to control the contrast you will do so according to what the result looks like and therefore compensate for the contrast effect that cyan has. But if you then adjust Cyan so that you can change the print time you will also adjust contrast. So yes you can use cyan filtration for ND but it isn't recommended.

I sometimes use Lee ND lighting filters above the mixing box in my enlarger. They are cheap because they don't need to be optically perfect as under the lens filters do. One sheet is big enough to cut up into squares and I use multiple layers to control the amount of ND I have. Being lighting filters they are also heat resistent (to a point).

neil poulsen
29-Oct-2006, 23:19
My advice is not to use it below the lens. I tried this in some testing that I was doing, and I saw deterioration of the image.