A couple of notes:(posted 8072 days ago)N Dhananjay wrote: "However, you are right, this would mean that contrast in the shadows should INCREASE. This would be because the shadows would suffer from much greater failure from reciprocity i.e., their densities would drop much more dramatically than the decrease in densities of the higher zones."
DJ, I think the increasing is not obvious; lets assume the normal curve is stright. Then, when we start experience the failure of reciprocity, the shadow part of the curve may become convex or it may become concave, -- it depends how fast drops the film sensitivity. -- Am I wrong? -- Undoubtedly is it worth plotting some curves. Very interesting idea.
Ryuji Suzuki wrote: "but the most likely reason staining developers can help achieving compensation is through local hardening of gelatin. The oxidation products of those agents increase cross linking of gelatin, making it shrunk, harder, as well as stained".
Ryuji, may be it makes sense to split the development into 2 baths: 1st does mostly sa elective hardening, the 2nd does mostly the very development? I think it is important to find a "sweat point" when the hightlights are hardened enough to impede the developer penertation, and the shadows are still penetrable enough. In case of success it can be goos means to tame the contrast in rotary processors.
And the 3rd possible way: Pre-bleach and overdevelop. D.Kachel's method of pre-development bleaching (applied to film) alows to "eat" the highlights, leaving the shados almost untouched. In other words in introduces a shoulder. If we then extend the development time I suspect we can essentially raise the contrast in shadow while keeping the contrast in midtones & highlights tamed (how much tamed --it probably depends on pre-bleach intensity). I never tried it, just an idea.
Great topic.