Re: [Leica] Exposure range of commercial film

["Dan Post" <dwpost@email.msn.com>]

Greg,
If you are using B&W film, a thicker emulsion film, like Plus-X or Neopan
and judicious use of under and over development, along with a good variable
contrast paper will get you up to 15-16 steps. I use a Kodak step tablet,
uncalibrated, as a guide for setting up my paper and the filtration for
different ranges of gray. I also use a meter in the darkroom to check the
range of the negative, and have used a modified zone system to get different
ranges of gray on the film. I used a target to set up the development time
consisting of a gray scale, a white card, a black card and a gray card. I
shoot short lengths of film at different EI, then develope each at a
different time, noting the range in a notebook for later reference. It is a
bit time consuming, but you can get your figures in an afternoon, and once
you do, thaey are good for that particular film/developer combination.
Color? Not easy. I work in a lab, and since most processing of film and
paper is done with very closely monitored temperature and time combinations,
there really is no "Pulling or Pushing" of color film. Even when I did it by
hand, I had irregular and unpredictable results.
I do use Kodaks Gold Max when I have some difficult situations. It
incorporates what Kodak calls DIR, or Developer Inhibitor Release. My
understanding is that if you over expose the film, say at ISO100 or 200
instead of the rated 800, the emulsion releases a developer inhibitor in
those overexposed areas, and this in turn keeps the highlights from burning
in or being blocked. We have had many problems before where some one with a
disposable camera gets too close to a subject, with a dark background, snaps
a shot and the face is a dense overexposed blob, and the background on the
film is very thin. High range of contrast, and very hard to print. Gold max
seems to resist this and areas of high luminance record a proportiantely
lower density. The DIR also means that the grain size for overexposed Gold
Max is actually FINER! I usualy shoot it at ISO 400 and print it on Kodak
Royal VII paper, and can get pretty good tonal representation. From my
experience, this film shortens the scale, becoming less contrasty with
overexposure. So far it is the only film to do this. I don't like the color
rendition as much as I do with Kodak Vericolor, or PMC400 but like I said,
it works well in difficult situations, and better than anyother film I have
used.
I might add that I did some Kodam T-Max 400 in a two part D-76 developer,
shooting at ISO 100 to 800; the density of the graycard in each frame was
within 10% of each other! They were all thin, and could have been done on
grade 3 paper, but it was as if the film could not be overexposed!
If you want to try that, I can e-mail you the developer recipe ( I got it
out of the 1947 Chemistry and Physics Handbook, published by the U.S. Rubber
Co.!)
Good Luck,
Dan'l
dwpost@msn.com
- -----Original Message-----
From: Gsam126 <Gsam126@aol.com>
To: Leica-users@mejac.palo-alto.ca.us <Leica-users@mejac.palo-alto.ca.us>
Date: Sunday, March 22, 1998 5:08 PM
Subject: [Leica] Exposure range of commercial film

>
>
>I've got a technical photography question which has escaped perusing a
number
>of book resources: What is the range of illumination, i.e., F stops, that
>print/slide film can normally handle. I'm interested in this from the point
of
>view of landscape photography, where graduated neurtral density filters are
>apparently used when, e.g., brightness of the sky may be far greater than
>other parts of the frame, creating a situation where  one can only expose
part
>of the image correctly. I encountered this while attempting landscape
photos
>in the Himalaya, where, at alttitude, distant mountains where extremely
bright
>relative to foreground. To capture them, the foreground would be
underexposed;
>to get the foreground, the background would be overexposed to the point of
>total loss of detail From reading, the solution is to use  the graded
neutral
>density filter. My question is , what is the exposure range (in F stops)
>beyond which  such comopensation is necessary. Looking in Adam's classic
tome
>"the negative" and the more modern  take on the zone system in grave's
book,
>there is no discussion of this issue. What is discussed is the range of F
>stops spanning zone 1 to 9 (10 stops). If the range of illumination in the
>subject is greater (which could be figured out by taking spot readings of
>darkest and lightest areas), the scene is considered to have increased
>contrast, and the film (B&W) can then be developed to expand its range of
>useful contrast. However, there must clearly be a limit to the degree of
>useful expansion. (This is also of limited use with color film). I have
been
>unable to find any written discussion of the exposure range for the
commonly
>available Kodak/Fuji films. Knowledge of this would be essential for
outdoor
>photography: to enable the photographer  to know when a given image would
>require a graded neurtal density filter. Also, can pre-exposure be used to
>solve the same problem? Vis a vis the G1/G2, has anyone come up with work-
>arounds for the difficulty (?impossibility) of using graduated neurtral
>density filters?
>I would appreciate some help. Thanks Greg Ruskin