Judy Seigel (jseigel@panix.com)
Fri, 22 Jan 1999 15:46:04 -0500 (EST)
On Thu, 21 Jan 1999, Adam Kimball wrote:
> I've been thinking about how I'm going to come up with a working curve for gum
> printing. This is my current idea- actually my interpretation of an article by
> Charles Palmer (on the Bostick and Sullivan page) which I don't totally
> understand, so humor me ;)
>
> First, make a 100 step wedge in photoshop using opacity. Print this out and wax
> it. Next, print this wedge alongside a Stouffer tablet on a particular
> emulsion. Say I get five steps of good tone on the Stouffer tablet - I make
> reflection readings of these steps, and find the five corresponding blocks on
> the digital UberWedge{tm} which produced the same tones. Now, I know how
> photoshop opacity correlates to continuous tone opacity. So, shouldn't I be
> able to use this data to plot a curve for photoshop? I.E. if stouffer 20%
> opacity prints X, and photoshop 10% opacity prints X, I can go into the transfer
> table and set the 20% value to 10. Correct or complete stupidity?
>
> Obviously, I am a complete beginner to digital negatives, but I'm not a complete
> beginner in photoshop and have some, be it small, knowledge of sensitometry.
>
> Any advice or comments would be appreciated,
Adam, I'll humor you til the end of time, but hear this: a "curve" for gum
is a chimera. That is, unless you want to back yourself into a strait
jacket -- because with each change of mix, color, size, paper, exposure or
development, even a new batch of gum -- the "curve" would change. However,
since the development is extremely flexible, you don't need a pre-ordained
curve. You weave and build as you go along. That is, if having learned
"perfect control" you can deal with that.
On the other hand, if you have in mind a *particular* type of gum printing
you want to do, and make a negative to exactly match that format... well
that could be as good an *introduction* to gum as any other. Just don't
forget that other possibilities abound.
Judy
This archive was generated by hypermail 2.0b3 on Sat Nov 06 1999 - 10:06:44