From: Jeffrey D. Mathias (jeffrey.d.mathias@worldnet.att.net)
Date: 10/30/01-09:16:49 AM Z
Judy Seigel wrote:
> ...
> Jeffrey, would you expand on that point please? I mean about Dmax &
> maximum black being different. Would this have anything to do with
> fact that if you put a step print on a light box you can see more
> steps than are visible by reflected light?
Yes, partly. Transmitted light will generally show much more in the
darker values. It must always be considered how the print will be
exhibited and viewed.
Direct sunlight or a very strong light can be used to view a print
(either reflected or transmitted). This illumination is much stronger
than typically used to view a print and will show more in the dark
values. Much more exposure can be given to the print and can produce a
darker black, but this additional exposure may also darken the other
values in the print. The key is to find the shortest exposure which can
produce the required black.
If one generates a test exposure strip of several steps from incremental
exposure (the increments are some even division of a stop), they should
note that each step will be slightly darker as more exposure is given,
and the difference between steps should become less, and eventually no
distinction will be made between steps. The illumination will influence
this and should be that typical of exhibition. When a step is selected
as maximum black, it should be considered normal that it can appear
slightly lighter than the darkest step when side by side.
The key is to select the exposure that gives a dark enough black, but is
close enough to having good discrimination from the shorter exposures of
Zone I. When this test strip is exposed through a film with base plus
fog of the image negative, this black will be the maximum possible black
that can be produced in the print. That is: if more exposure is given,
the print will look too dark, and if less exposure is given, the print
will have a lighter maximum black.
Note that this does not include solarization or reversal effects which
might be produced with increased exposure. It does seem the nature of
photographic materials to be capable of producing a more solid density
than typically usable which can be observed by overexposure and viewing
with a stronger than normal illumination (and transmitted shows more
than reflected). Also keep in mind that even if the print is to be
viewed with transmitted illumination, the maximum black selected will be
lighter than the maximum density possible.
Also associated with this is the range of values (dynamic range; overall
contrast). Exposure and contrast control can influence each other which
is one reason I have suggested a simultaneous calibration of exposure
and development when making negatives. For example: if the contrast is
increased so as to keep the upper values from getting dark when more
exposure is given to produce a darker black, the resulting print may
have too much contrast.
-- Jeffrey D. Mathias http://home.att.net/~jeffrey.d.mathias/
This archive was generated by hypermail 2b30 : 11/02/01-08:55:27 AM Z CST