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Hi. I just got back the results of a paper and film test that I had done by a third party, using the BTZS software. I don't understand the results I got back. I sent four paper samples--ilford multigrade, Azo developed in Agfa neutol WA, cyanotype on ARches platine, and cyanotype on Crane's platinotype. The film I sent was TriX 8x10 processed in D76.
The resulting curve families only show the ISOs for Ilford and for the film test, which I think assumes that the paper has an ES of 1.24. The results say that I should use the same ISO results for all four papers. Is it likely that this could be true? The cyanotype papers has an ES of 1.98 and 2.1, much different than the ilford and azo. Also, even for the Ilford and Azo, the ISOs don't vary much; they hover between 250 and 320 for all density ranges between 4.4 and 7.4.
Another confusing thing is that on all the sheets of paper I got back, it says at the top that the film ISO is 200. But that is not one of the ISOs that I am supposed to use.
Only one of the curve families--the ones for Ilford--show the triangle's placement, and nowhere is the ISO ruler shown. Again, on the curve families for the other papers, no ISO is indicated on any curve.
When I talked to the proprietor of the business that did this test for me, he said to use one film speed chart for all four papers. This chart shows five points hovering between 250 and 320.
I am shooting now on the assumption that SBRs in the range of 7 are going to be shot at about 250 and those 6 and below should be shot at 320. I hope that is correct.
--shannon stoney
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