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Response to Mortensen and Gradation

from N Dhananjay (ndhanu@umich.edu)
I suspect this might well be the case - its probably related to the local contrast issue David Kachel railed about in his articles in DCCT. I suspect it is fairly common to have perfectly tailored negs which are them printed on higher contrast paper to ensure sufficient local contrast in some key area (followed by the necessary heroic dodging and burning) - the simplest example is how doing an N- leads to somewhat murkier shadows but there probably are more complicated situations.

Expanding a limited scale subject ensures good local contrast throughout the image. However, I think this is something that is worth being careful with these days. I guess these are personal decisions but I see many pictures with overly harsh local contrast - they are very dramatic but seem to lack subtlety to my eye. Papers have improved substantially from the old days (in terms of Dmax). This means that papers probably can hold more information and expanding limited scaled subjects onto such papers can make for enough distortion of reality that I think one needs to be exercise considerable sensitivity to the subject and image.

Its not much help in the more complicated situations when one needs to hold a longer subject luminance range and yet ensure sufficient local contrast in some part of the image - I find those kinds of subjects troublesome in the extreme (sort of broad level controls during neg development but more often than not demanding in the printing stages). One could find ways that work for a particular kind of photography - for e.g., the typical landscape concern of ensuring sufficient detail (local contrast) in the shadows while holding a longer range lends itself to some overexposure coupled with some kind of compensating technique.

I think there is another issue here beyond local contrast and that is related to how film and paper work together. One will often hear people talk about platinum's longer scale etc. However, actually, silver gelatin papers typically have considerably higher Dmax than platinum papers. Which means that they should have a longer scale. The problem is that the silver enlarging process relies on a low contrast (gamma or slope of HD curve) negative combined with a high contrast paper (as opposed to platinum - you seem to develop to about slopes of 45 degrees or thereabouts - sort of a 1:1 relationship). That means there is considerably more accuracy required in the silver development process, minor changes in the curve shape can have dramatic influences on the final print. Also, typically development slows down as it proceeds (an overgeneralization but some grain of truth to it) i.e., the early stages of development are very sensitive to minor variations. Expanding scales implicitly means developing to a higher CI and therefore ending up in the more stable region (I'm curious, which negative do people typically have trouble printing - N+ or N- : for me, typically the N+ print with no trouble at all). I think that is because there is less compression/expansion going on in each stage.

Cheers, DJ.

(posted 8482 days ago)

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