U of S | Mailing List Archive | alt-photo-process-l | Re: pt/pd stops

Re: pt/pd stops

Chris wrote:

I am interested in the utmost capability of a pt/pd print in terms of stops--to compare with bw, cyanotype, gum, etc. I have gone back and started reading Mike Ware's Cyanotype book again and find it is SO worth reading because each time I return to it I find more.

Indeed.  Would that all photo process books were that well researched and presented.

In the BW darkroom I did an interesting visual of printing a Stouffers with every filter in the Kodak filter pack to illustrate the tonal range/number of stops each filter produced.  Very illustrative of the effect of filters!  I'm tempted to post one more visual :) 
But no one would print with a 1 or 0 filter which, if memory serves correctly and I am too lazy to go get the step wedge prints, gave the longest tonal range. 

Yes, the lower the filter numbers (which were originally intended to more or less match the contrast "grades" of graded papers), the longer the exposure scale ("ES").  But why wouldn't one use grade/filter 0 or 1 if s/he had negatives that had a DR comparable to the ES of paper grade/filter 0 or 1?  To print my Pt/salt paper/albumen/cyano negatives straight onto SG paper, I would need grade/filter 0000 SG paper.  Lacking that, I have to resort to tricks (masking, latent image bleaching (SLIMT), copy negatives, etc.) if I want SG prints from those negs.  Granted, most people who make "normal" negs don't generally need grades/filters below 2 or above 4 or 5, unless they are making split-contrast prints.  But if you make negs that have a DR that matches the exposure scale of grade/filter 0 or 6 and want full-scale prints, you need grade 0 or 6 printing materials.  Ditto, if you want to make prints that have either less than full scale or blocked shadows and/or highlights, from "normal" negatives.  If it's what you need, it's good to have.

Best regards,