Re: Gum tonal range (was Miracle size for gum)
Loris wrote: I wasn't talking about the sensitometric response of the emulsion, but about the practical consequence. (What you can't put on paper doesn't count, does it?) Gum and carbon aren't much different in that aspect my experience is they behave pretty similarly; highlights are always higher constrast and tonally less smooth.Again, this has not been my experience with carbon, nor do I see any evidence of it in the carbon prints made by Sandy King and some others. I don't know whose carbon prints you are looking at, but I am used to carbon prints with wonderfully smooth and subtle highlight tones -- certainly the equal of the very best that silver gelatin can produce. This is borne out by the densitometry. Sandy has some fairly typical transfer curves in the article posted at: http://www.alternativephotography.com/articles/art110.html His curves are not exactly like mine, but they show the same kind of toe (which is the part of the curve that produces print highlights). Not as soft a toe as Pt, but softer than silver gelatin paper. You can lengthen the toe by preflashing, just as you can with gum, to get a characteristic very similar to Pt. I don't understand what you're trying to say about sensitometric response -- the sensitometry/densitometry of a printing process measures nothing but what is put on paper -- "what you can't put on paper" (whatever that is) isn't measured. Best regards, etienne
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