[pure-silver] Re: History... Clarification
- From: Jean-David Beyer <jeandavid8@xxxxxxxxxxx>
- To: pure-silver@xxxxxxxxxxxxx
- Date: Tue, 20 Oct 2009 07:35:46 -0400
C.Breukel@xxxxxxx wrote:
Jean-David,
Interesting material to read, cannot say I follow everything, but..
bounce@xxxxxxxxxxxxx] On Behalf Of Jean-David Beyer
I have found that with problem negatives, a second exposure with the lens
stopped down considerably can be used to burn the highlights. In theory,
you could do even more, but I have never found it necessary.
..I guess you are referring to screen negatives, not "standard" B&W
negatives?
Right.
If you are referring to B&W negatives, could you elaborate a bit on this?
No, when making prints from plain negatives, the aperture does not make much
difference, other than those related to reciprocity failure.
The trick with half-tone is that the % dot area depends on the aperture of
the lens and the screen height and pitch. So if you need (making up the
numbers here) f/22 with a screen height of 3/16" to get 100% dot area, if
you reduce the aperture to f/45 or f/64, you will expose only the centers of
the dots. And if these are large already from the initial exposure, it will
not make any difference. But if they are small dots or no dots at all, they
will bet bigger, essentially burning the highlights without affecting the
middle or low tones at all.
In amplification of this, if the aperture of the lens is too small or the
screen height is too high, no amount of exposure will get you the largest
(100%) dots.
--
.~. Jean-David Beyer Registered Linux User 85642.
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