FotoDave@aol.com
Fri, 22 Jan 1999 11:39:23 -0500 (EST)
Joao,
Agfa makes very good products, so I am not surprised to hear that the
imagesetter film does NOT work so well for you, but with more tests and
studies, you might still make it work.
Imagesetter film (actually lith film also) has a requirement and desired
characteristic exactly opposite to what we need. To make good dots (or lines),
it must give high Dmax and low (narrow) exposure range (so that dots can be as
hard as possible). We want the opposite, so buy cheap stuff(!) where the
requirement is probably just met but not the greatest.
High density needs lots of silver, thus requiring lots of developing agent to
develop it completely (in a reversal process you need to develop as much as
you can so that it get bleached out as much as it can so that you get low
Dmin). This might have caused mottling problem if your developer is not
enough. Try using a small piece only and project or contact and step tablet,
and use enough first developer and good agitation to at least check if it
solves the mottling problem.
<<there was a pronounced strait line and
a few weaker others crossing the smaller side of the film, just as if I
had photographed a creased sheet of paper, it looks like a got of a
creased paper image behind the image I printed.>>
You mention that the film looks transparent. It probably does not have an
antihalation layer. This might have caused the line problem mentioned above.
Is your baseboard black or is your easel painted black? If not, the lines
might be caused by reflection from the baseboard or easel. Put a piece of
matte black paper under the film when you expose it (that is, if the base or
easel is not black).
Now, to see if the exposure range is good to be used for continous tone, you
can check the range by exposing (or contacting) a step tablet, use D76 1+3 to
process it normally (as described in my article). Don't worry about the
reversal yet. The image is formed mainly from the exposure and the first
developer. Later exposure and redevelopment can be carried out to the full, so
they are not that critical.
If anyone want to use the reversal method but needs to run tests because of
different material used, make sure you read and understand the concepts
mentioned in the continous-tone development of lith film. Surprisingly
(actually not surprisingly), the concepts are exactly the same whether you do
normal development or reversal processing.
(When I got into photography, I found that one of the most illogical terms
people used was "reversal." With my simple logic, if you use a negative and
get a positive, that is reversal: the tones are reversed; if you use negative
and get a negative or use a positive and get a positive, that is NOT reversal;
nothing is reversed. I think the term "reversal" has some historical origin
and it cannot be changed now, but it is so illogical. Oh well.) :)
Dave
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