From: Judy Seigel (jseigel@panix.com)
Date: 02/05/03-01:31:59 AM Z
On Wed, 5 Feb 2003, Richard Urmonas wrote:
>
> I have observed this with salted paper, where during my exposure
> calibration tests, I obtained a print of a 21 step with 12 dark steps,
> with the steps just discernable from each other and above these
> the well seperated steps in the "straight line" part of the curve.
Why do you think that's self-masking & not just more toe? The "toe" is by
definition not well separated, which is why it's the "toe" and not the
straight line. As for "over-exposing" to cause it -- why is that the
definition of "self-masking," which I would assume would have to happen
willy nilly whether over or under or just right exposed.
> If the process gives well seperated steps with a distinct Dmax
> then it is not self masking.
You're saying there's no self-masking in the straight line, assuming you
print so there's just a straight line? But if there is self-masking it
must by definition occur in a pop process at the dark end, however the
steps go up. So this strikes me as not at all what's meant by the term as
generally used.
My students used to notice that when they printed their view camera negs
for VDB they got better shadow separation than they had in silver. The
"explanation" I offered was "self masking." Of course maybe if they were
better printers or used a VC paper they could have gotten that same shadow
separation in silver. But, as I see it, self masking is variable and
uncontrollable, and only provable by comparison with an entirely
DOP process, if that. Maybe VDB just has a longer high toe than SG...That
is, the whole thing may be a matter of semantics.
Meanwhile, AFAIK, over-exposure is not in the description of self-masking.
I also think that any overexposed print could show those close dark steps.
Put a silver gelatin print that's over exposed on a light box and you'll
see several more steps.
Judy
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