I have an old, but still very wonderful, book on Astrophotography. In it there is an extensive section on photographic science, including an interesting section on fine grain development. Let me precis a couple of sentences from it -(posted 8440 days ago)There are at least 4 ways of achieing fine grain - 1)develop to a low value of Gamma, either by diluting the developer or reducing dev time. This results in a serious reduction of emulsion speed. 2) Physical development whereby the sensitised halide grains are coated with metallic silver from the developer. Reduces the films EI 3) Use of solvents in the developer, which eats away the outer regions of the halide grains as development proceeds. Since some grains a disolved before development occurs, there is some reduction in EI. 4)The use of p-phenylenediamine as the developing agent. No developing agent produces such fine grain, but it is far more toxic than other compounds.
I found this all quite interesting. Method 2 I have never heard of before, and dont quite think I understand it as it was written. But the other three points lead me to ask 3 questions :
Method 3 is of course part of virtually every dev. formula. We see it in the form of Sodium Sulphite. This chemical acts as a preservative, but also as a solvent. I dont recall seeing any dev formulas that do not have enough Sod Sulphite not to act as a solvent. Has anyone experimented with developers which do not have Sod Sulphite? This would require either that the developer be used shortly after mixing, or that other preservatives be used in its place.
Is it possible to take a 'high contrast' developer (I dont quite know enough about this term, but perhaps dev D-8 is an example) and then 'underdevelop' to give normal contrast with finer grain? I suspect that the grain wouldnt be that fine in this case. Has anyone tried this?
Finally (whew!), p-phenylenediamine. A page at www.unblinkingeye.com mentions that it is rarely used, which certainly seems to be the case, but it appears to be in Tetenal Emofin (read the contents of the packet), and I think in D-12 (although I have never seen the formulas for either of these developers). Has anyone use this chemical and what do they think of it. Are these published dev formulas that incorporate it?
Thanks, I know this has been a long one!
George