RE: CMYK separations on Adobe Photoshop

Keith,

If I am understanding you correctly I think there is a glitch in the
test you propose. If by "lith film" you refer to an orthochromatic
emulsion, then the spectral sensitivity of that film will distort the
red response in the copy negative(s). I think you'd have to use a
panchromatic film to retain something close to the original color
information.

Of course, for all I know the CMYK inks that the Epson 2200 uses when I
make digital negative separations might also be causing a spectral shift
even though the negatives look neutral in color.

In any event, to make the comparison more attuned to the scientific
method, you'll want to hold as many variables constant as possible. As
a result, one thing to do is to divide the printing substrate in half
after it is prepared and coated evenly with emulsion. Then,
simultaneously print both halves using the same exposure and process
them together. You can't always control everything precisely, but you
can get close and at the same time make it similar to your normal method
so that the results have some practical rather than purely theoretical
value.

Joe

>>> Keith@gumphoto.com 11/04/04 9:52 PM >>>
Soon after making this reckless statement, I realized how much work I
had
gotten myself into. (My negatives are on lith film made in the
old-fashioned way: in a soon-to-be cold darkroom, and I hate it.
darkroom
work, that is). So this is what I'll do: I will make a diptych where
each
half is of the same subject shot at the same time. In other words, I am
reneging on the offer to make two versions with identical source, but
they'll be pretty darn close to being identical. I'm thinking of
something
on the order of a nude with two similar poses side by side. And, I
suppose
if this effort is going to result providing any valid new information, I
ought to stick with a conventional color palette and play by the rules,
i.e., attempt for a "true" representation of the original shot. And
yes,
I'll record and publish the steps in the process.

Anybody have any other suggestions? I'm new to this whole "scientific
testing" stuff.

-----Original Message-----
From: gdimase@hotmail.com [mailto:gdimase@hotmail.com]
Sent: Thursday, November 04, 2004 4:26 PM
To: alt-photo-process-l@sask.usask.ca
Subject: Re: CMYK separations on Adobe Photoshop

Keith wrote:
I will personally
> make two gum prints, one using CMYK negatives and the other using RGB
> negatives. OK? I am confident that this demonstration will prove
that
> neither has an advantage.

Can we also get the details of your conversion to CYMK on Photshop (UCR,
etc.)
Thanks,
>
Received on Thu Nov 4 20:34:48 2004