From: Jeffrey D. Mathias (jeffrey.d.mathias@worldnet.att.net)
Date: 04/25/00-03:07:59 PM Z
Sandy King wrote:
> A question for those who use the sun as UV light. Do you expose with
> the contact frame in full sunlight or in the shadow? Does it make a
> difference in terms of apparent sharpness?
I have printed Pt/Pd in both direct sun and shade (indirect sun) from
the same negative. There is a difference in the look of the prints.
However I would not attribute the difference to sharpness. The apparent
sharpness can look identical. The sharpness is much more a function of
the paper selected than the direct or diffuse exposure light. Perhaps
the paper surface of even a smooth paper hides any supposed difference
from light sources.
Some may attribute a change in apparent sharpness to a change in
contrast, but I do not. So be the nature of apparent. Just as some
lens manufacturers claim to have better sharpness with a higher contrast
lens. The lower contrast lenses can produce just as much detail, and
perhaps more. But resolution is not quite sharpness. Sharpness would
seem to be more of differences along the gradient of the optical modular
transfer function. But then, what appears may be different altogether.
Another tid-bit related to sharpness. I have found that a Pt/Pd print
from Tri-x film (relatively grainy) will have much more sharpness and
detail in the print than a print from Tech-pan (high resolution film).
And the Tech-pan negative does have more resolution and detail than the
Tri-x negative. But the prints do not see the resolution of the
Tech-pan. It is thought that the grain provides a better difference (or
step) along the gradient of the optical modular transfer function which
is seen as greater sharpness in the print (revealing more details from
the negative).
-- Jeffrey D. Mathias http://home.att.net/~jeffrey.d.mathias/
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