[pure-silver] Re: Densiometric Testing Of Old Film Pack
- From: Myron Gochnauer <goch@xxxxxx>
- To: Pure Silver group <pure-silver@xxxxxxxxxxxxx>
- Date: Fri, 10 Mar 2017 00:19:25 +0000
New TXT in DK-50 1:1 shows a FB+F of 0.18
... the TXP negs (again in DK-50 1:1) show a FB+F of 0.28 or 0.1 DU
Still, 0.1 DU is not exactly a huge problem - we'll see when I go to print
these - but it likely accounts for slightly underwhelming contrast under
visual inspection.
Hmmm. What does that actually mean for exposure of the film? Your unexposed
but developed film has a density of 0.28. Now, suppose that you give a frame
just enough exposure that it should (were there no fog) be 0.1 DU about base +
fog. Am I correct that developing film with this exposure would look *exactly*
like the unexposed (but fogged) film, the "fog" in effect "using up" the silver
halide particles that would have responded to the exposure? If that is so, it
would seem that the fog has simply "used up" Zone I, as it were, reducing the
range of the film.
Nonetheless, 0.1 DU *is* pretty small. The printable density range you're
dealing with for normal scenes and middle contrast paper is probably in the
order of 1.20-1.30(?), so increasing the contrast enough to overcome the bump
of 0.1 to the bottom end should not be difficult.
I can't recall the numbers now, but the base density of 35mm film must be at
least that much more than the clear base of 120 and larger films. "Printing
through" the density would be trivial.
Myron
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