[pure-silver] Re: safe light
- From: Martin Jangowski <martin@xxxxxxxxxxxx>
- To: pure-silver@xxxxxxxxxxxxx
- Date: Mon, 9 Jun 2008 14:53:12 +0200 (CEST)
On Sun, 8 Jun 2008, Mark Blackwell wrote:
Now for a way to test it. Here is a suggestion. First pick a spot not
too far from your safelight, one near your enlarger, and one near where
your developing trays are placed. Set a sheet of photo paper there and
put something on top of a part of the paper. I use a quarter. If your
budget allows a silver dollar would work too grin. For most accurate
results place the sheets and the money on the paper in total darkness.
Some can do this all at one time and others might prefer to test each
location individually. Turn the safelight on and leave everything there
for about the same amount of time that it would be there while doing the
actual work.
The next step is to develop the blank paper normally. IF your safelight
is really safe, the paper should remain white. If it isn't, the outline
of that quarter should appear and the rest of the paper should have some
sort of change depending on how safe it isn't. Solid black with a
quarter outline is real bad grin.
This method is good, but has one flaw: You will operate the paper at its
lowest sensibility at the toe of the density curve. A better method is
nearly identical: Pre-expose the test strip with white light. Adjust the
exposure time that it will give a medium grey after development.
With this pre-exposure the additional exposure from the safelight will be
visible at the steepest part of the density curve. It is entirely possible
that a safelight that passes the white paper test will visibly lower the
gradation of the same paper.
Grüße aus Hohenlohe,
Martin Jangowski
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