Dichroic head settings for Polycontrast and Multigrade papers

[John Irvine]

I used to have an article on settings for a dichroic head to use in place of Polycontrast and Multigrade filters. I carefully filed it away and promptly forgot where. Anybody out there got something like that? Also, can Polycontrasr filters be interchanged with Multigrade filters?

 

[Bob-D659]

See the insert from your photo paper or the mfgr's web site. Also maybe/depends, on when they were made. Filters have changed over the years.
I have some rather ancient sets of Ilford, Dupont and Kodak filters, they are all different from the current Ilford ones. They will work, as they all use similar filters, I just don't think it is worth the effort to figure out which is what grade, and to do that you need a new set to compare with anyways.

 

[ic-racer]

The info with the Ilford paper works well for me. Works pretty will even with non-Ilford paper.

See Page 3: Dual colour filter settings

http://www.ilfordphoto.com/Webfiles/2006130201152306.pdf

 

[srs5694]

I've seen enough different tables, and experienced enough variability from one brand of paper to another, to think that the tables must either be customized for each paper/enlarger brand or they're just rough guides. IMHO, the main reason to use them is to take advantage of the "constant exposure time" tables, so that you can adjust the contrast without adjusting exposure time. If you're not interested in this, just change the yellow and magenta filtration until you like the contrast and don't worry about the equivalent paper grade. Alternatively, you could use split-grade printing, in which exact grade correspondence isn't an issue.

 

[Shawn Dougherty]

This is a perfect opportunity to learn split grade printing (if you don't now). It's the only way I print with VC paper. I also use a dichro enlarger, all you need is 1 and 5, usually full magenta and a little off full yellow. See Les McClean's article on the subject. All the best. Shawn

 

[John Irvine]

Thanks. I finally found the old article I was searching for. As discussed above, it's just a rough guide. Comparing the article with the Ilford information, you get different settings. From the comments above, it looks like the numbers are not extremely critical. The problem came up because the Omega enlarger I use for 35 mm doesn't have a filter holder and I'm not coordinated enough to hold a filter with one hand and dodge and burn with the other.

 

[Mike Wilde]

custom dichroic setting idea

I semi- frequently have half used boxes of VC paper come my way. A lot quite aged.

So I test them to calibrate how they behave now with a series of 10 step wedge exposures on slips if 1x5 that I have left over from cutting a few 8x10's to 5x7's. I go from max magenta to zero magenta, then max yellow to zero yellow, and count the number of steps distinguishable in each exposure with a differnt filtration (label on the back with a sharpie to keep them straight, and process all with the same time agitation, etc. in the developer.

Then you can figure out the most yellow or magenta that yields any difference in contrast grade and then can calculate how much magenta to dial agaist a yellow to keep a constant espoure time for middle grey, etc.

I write up a little table on a post it, and tape it to the front of the paper envelope. It saves a ton of time when you decide that you want to change the grade, and do not have to spend time refining the basic exposre time change after changing the head dial settings.

Anshell outlines the full proceedure in 'the varible contrast printing manual'.

I know from this for example that I have about 250 sheets of getting on polycontrast III 8x10 glossy (now in my freezer) that is never going to be harder than #3.5. So it goes to contact sheets. I can then know what the relevant dichroic numbers are when I might want the same contrast on a different paper I am using to enlarge on.