[pure-silver] Re: contrast problem
- From: "Richard Knoppow" <dickburk@xxxxxxxxxxxxx>
- To: <pure-silver@xxxxxxxxxxxxx>
- Date: Sun, 28 Feb 2010 12:11:39 -0800
----- Original Message -----
From: "Shannon Stoney" <shannonstoney@xxxxxxxxxxxxxxx>
To: <pure-silver@xxxxxxxxxxxxx>
Sent: Sunday, February 28, 2010 10:30 AM
Subject: [pure-silver] contrast problem
I just checked two strips of paper side by side. One was
the 11x14 paper and one was the 8x10 paper. The 11x14
paper is definitely flatter. I had to print it at a half a
paper grade higher than the 8x10 paper.
So much for work prints.
So, the paper in question was Ilford warm tone glossy. I
still love this paper, but caveat emptor.
--shannon
I don't have a copy of the ISO standard for paper
contrast or speed. Such standards exist but, without knowing
the limits and errors allowed, its impossible to know how
much variation is allowed in a commercial product.
Also, the filter sets for various makes of paper are
not the same. Kodak and Ilford are certainly different in
_effect_ as well as visually. I have never seen a controlled
test of the effect of the filters with various kinds of
paper. One clue is the difference in the filter settings
specified for color head enlargers for different papers. If
the papers all responded the same the settings would be the
same.
As Tim Rudman pointed out the visual effect on the
print is the criterion but having some data about the
material makes it easier to obtain the desired result. The
difference in the two papers does not mean there is anything
wrong with either or with your printing set-up. Graded
papers would be the same since the specification of grade is
based on a measure of contrast index and does not take into
account any differences in the shape of the characteristic
curve.
The moral of the story is to test on the exact paper
one will use for the final print. If you make a lot of large
prints it will probably pay to sacrifice a couple of sheets
to cut them down for smaller work prints.
BTW, I've never had much success with test strips
beyond establishing the basic speed of the paper/enlarger.
There is too much illusion in the strip overlaying the image
to make a close judgement about contrast and exposure from
it. A small test print is very helpful. I also use a simple
enlarging exposure meter. Mine is an Ilford EM-10. I think
these are still made. It is a simple match meter, not a
calibrated meter, although you _can_ calibrate it. It is
very helpful in establishing initial exposures and in
adjusting exposure when the size of the print is changed.
--
Richard Knoppow
Los Angeles, CA, USA
dickburk@xxxxxxxxxxxxx
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