Ender100@aol.com
Date: 09/21/02-10:52:44 PM Z
Judy,
<<Frankly, I can't figure how I'd do that for gum -- because there is no
absolute:>>
I guess it can't be done then.
heheheh just kidding. You are right, there are a lot of variables, probably
more with gum than with a lot of processes... but still, you might be able to
come up with something workable. Make an un adjusted steptablet and print it
with your favorite combination of things or one that you think is "in the
middle". Then read the printed step tablet with your reflective densitometer
and use those values to target your curve.
Maybe you could coat some extra paper and do the above, then tweak your
values upon doing a second print of the modified curve... etc. etc. etc. I
think that is what I would try doing. It might not be that necessary.
When you say you can get 5 steps now, is that 5 Stouffer steps? heheheh
Seriously, if so, then that may tell you what your maximum useable density is
on the digital steptablet, if they are translateable. I am not sure yet they
are.
For example, if the maximum density on the Stouffer's is 3.0 AND I was able
to get a max density of 3.0 with my pigment inks on Pictorico, then I should
be able to print a steptablet that is identical to the Stouffer's.
Theoretically, they should print the same on about any process. However,
since they are different materials, and might block UV differently, perhaps
they would not have the same effective density. Anyone have an idea on this?
It's something I want to test when I get my NUARC unpacked. I wonder too if
pigment inks block UV differently than dye inks?
Maybe there is a holy grail of Alt Photo..... The UV adjustment curve that
works for all processes! heheeheh probably not, but I would think tBoy, we
owe a lot to Dan, he's done a lot of work for everyone. If people don't have
his book, they should get it, if they are trying digital negatives.
One last thought on all this. Imagesetter images work differently from
silver negatives, in that they print halftone. Except for Dan's spectral
negatives, I think perhaps inkjet negatives workt he same, since they are
either dots or spaces. So perhaps these negatives behave a tad bit
differently than traditional negatives?
Mark Nelson
In a message dated 9/21/02 11:37:12 PM, jseigel@panix.com writes:
<< > I think the only readings you really need to take are reflective
readings on
> the final print of your steptablet using whatever process (gum, platinum,
> etc) that you are using.
Frankly, I can't figure how I'd do that for gum -- because there is no
absolute: not like I had, say, a platinum emulsion, and did a curve to
make it behave. A reflective reading from a gum step tablet would only be
for that particular amount of pigment, color, ratio of dichromate to gum,
& length & type of soak... but these tend to vary by layer, paper, whim,
image, and available temperature.
I'd like a curve that would just print, say 8 differentiated steps. I
could get the 5 or 6 steps that's the average for average gum emulsion &
development, with range left over to fill in with subsequent colors.
Any ideas what could do that, or is that the part I've got to figure out
myself?
Meanwhile, I DID get Dan's curves on the desktop by pressing option key --
hoo ha !-- with many thanks to digital mavens in this crew. But Dan --
where was the "gum curve"? I opened every one that looked possible, but
the only one that seemed at all possible was the cyanotype curve, which I
loaded & will try.
Interestingly, it was somewhat like the curve on all my 4 tests so far.
It turned out (which is why actually charting curves is such a revelation,
at least around here) that even though the NUMBERS of the high part looked
very different for each material, the rest of the curve was quite similar.
The section with the first 5 (densest) steps ranged from very steep to
practically vertical, but after that the 4 materials were just about
parallel to each other and virtually flat.
Very curious.
TBC. thanks again so far.
Judy >>
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