Hans Oosterom (hans.oosterom@wxs.nl)
Mon, 18 Jan 1999 10:58:18 -0100
Well,
being on this list as a lurker for a while, I feel that I should share what I
know on digital negatives. (that are for me positives)
I'm using them for photoceramics on a polymer sensitive layer that completely
burns away at 450 C.
I used a HP laserjet 4P, that had rather big dots (worked at 600 dpi
although). The density was just allright but could have been better.
The image on plain paper was allright, but gave often a kind of banding.
On acetate it was bad, due to strikes and banding and as well the heating that
is melting the toner to the acetate is affecting the acetate so that it isn't
flat anymore.
I must admit that HP wasn't happy with the result either and they changed the
machine for a 5MP.
Also 600dpi with RET and whatever, the result on paper is a much better image,
however on acetate the same effects take place AND the density is less.
Thinking about the density it is quite normal that as the toner gets finer,
the dots can be smaller (which is good) but they get lower as well (which is
bad for the density but good for the dotgain)
So I decided to print on calque-paper, that still is giving a too low density
and than transfer it to lithfilm, of which I am using a UV type as I don't
have a darkroom(yet).
I have tried several Inkjets a couple of years ago HP as well as Epson. I
realize that ink is THE key to it and that developments are going fast. But in
1996 I tried what was suggested on this list and pushed the amount of ink to
over 100%. Even on the special acetates that are sold for Inkjets the ink run
away at 150% max. And of course on 100% it didn't give enough density.
Having stopped my ceramic activities for about 2 years I am starting them up
again. One of the first things that I have done is doing tests with digital
negatives from a service bureau. At 200 lpi they do fine, although I still am
in the process of calibrating. They have more details (of course) and a good
density and at a reasonable price, however I feel as a problem that you
cannot test and redo your negatives directly.
What I still would like to do is comparing a 200lpi neg with a continuous tone
negative of the same size, just to the final heated result. But the price
range between a dig neg (in service) and a cont. tone neg (as well in service)
is 1:20 which makes the experiment expensive.
Hans
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