Re: Gum bichromate and photographing the nude, was Re: "CALENDAR ARTIST"

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Ender100@aol.com
Date: 09/10/02-11:16:09 PM Z


Judy,

I agree that there are a lot of variables... I would be talking about one
printing with the same paper and same mix and same time of day and same pair
of underwear.

It would be interesting... think I will get out my ol densitometer and step
wedge and see if I can compute a curve.... well in a couple of weeks, maybe.

Mark Nelson
In a message dated 9/11/02 1:09:08 AM, jseigel@panix.com writes:

<< In my experience a "photoshop curve for gum" would be like trying to pin
down a shadow. You can of course make a curve for gum (I've made one --
all I have to do is figure out how to save it and apply subsequently to
the next negative -- a not insignificant detail NOT covered in the manual,
or in Burkholder either as far as I can tell).

Granted I'm at the bottom of the learning curve "curvewise," but it's been
clear from the outset from comparison tests that any "curve" would vary
with the substrate you're making the negative on, as they print with
different contrast ranges, also the printer you're printing it with, plus
of course your style of gum -- what paper, one coat or many, color sep or
monochrome, ratio of sensitizer, method of development, etc. etc. etc.
etc. etc. Gum isn't platinum printing ya know.

You also have to decide whether your "curve" would be to get all the tones
in one coat, in which case it would be flat indeed, or to permit adding in
more steps with subsequent coats, which can be used to add colors, tone
shadows, increase density, do highlight detail, & so forth -- which are
much easier to achieve with a negative that's contrastier than a single
coat.

In short, a one-curve-fits-all for gum sounds like a contradiction in
terms. >>


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