From: Richard Knoppow (firstname.lastname@example.org)
Date: 07/28/03-03:51:25 AM Z
From: Halvor <email@example.com>
Sent: 07/27/03 06:18 PM
To: "firstname.lastname@example.org" <email@example.com>
Subject: Naive B/W (okay s/g)neg. ((pd/pt)) question.
> Hi group,,
I was just wondering, is "normal" black&white neg films somehow optimised
for the contrast/density of normal grade B/W papers ?
I assume the "target" density range of the neg should match the tonal
lattitude of the paper. Or is simply the flexibillity of silver density in
combination with the multitude of development possibilities large enough
that this is not really an issue ?
I mean, is there an "optimal quality" point for gamma/sharpness/grain
and so on, or is this all up to what you dip it in and the weather ?
if so, would it be possible (/ any point in), designing a(n ideal) film
Not that I have any plans to start any project of this kind, just curious.
At the risk of very much oversimplifying the answer is yes.
The development recommendations for film is intended to develop it to the right contrast for an "average" scene to print onto "normal" contrast paper. There are some qualifications necessary for a complete answer but in general the above is true.
Much of this is based on very extensive research done by Loyd A. Jones of Kodak Research Laboratories over a period of several decades. Jones and his associates measured the brightness range of hundreds of typical scenes. They also did very extensive work on how exposure affected the quality of the resulting print. At least at Kodak this work must have been applied to the selection of the contrast values for film and paper and for the shape of the characteristic curves for film.
In a way Jones' work runs counter to the Zone System. The idea of the Zone system is to choose exposure and development so that the range of densities in the negative will fit onto "normal" grade paper regardless of the scene contrast. This results in distorting the scene contrast. Jones method was to shoot at an exposure which would just result in adequate shadow detail and adjust contrast by choosing a paper grade to match the negative. This also can result in a distortion of the original scene contrast.
To some degree the eye is very tollerant of such distortions. The proof is that one can look at reflection prints, which nearly always have less range than the original scene, without their looking immediately abnormal. However, at some point and with some scenes the distortion of "local contrast" will give such an impression. While it may be desired to show detail in both deep shadows and extreme highlights, and while it is possible to lower the contrast to give such a result, it won't be acceptable to most eyes.
Ansel Adams used more than simple contrast adjustment to gain such detail, he used dodging and burning to control the range of parts of an image with a wide range of brightness but at the same time leaving the "local" contrast at a normal level so that the prints don't look flat. This is a lot of work for some images but IMHO is the only method that gives really good results.
Using the Zone System can insure than you have a printible image on the negative but the contrast adjustment of the negative, by itself, is not enough.
Film in general, will tollerate enormous amouts of over exposure but not much underexposure. Jones, et.al. were making use of this in deciding on a system of constant exposure and contrast.
I am not at home at the moment but will post some references to Jones' work later. Its worth reading over. Good summarys are in a couple of older books. Again, I'll post references later.
Los Angeles, CA, USA
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