Re: Density

William Patterson (wpatterson@ASAP.Bus.Wisc.Edu)
Mon, 24 Jun 1996 12:36:06 -0500 (CDT)

On Mon, 24 Jun 1996, TERRY KING wrote:

> To Defenders of the Faith in the Zone System.
>
>
> Klaus asked why neither Judy nor myself had said what objections we had to
> the zone system. It is not for me to speak for Judy.
> I do not object to the zone system ! ! ! ! ! ! !. BUT :
>
> !. The zone system was designed to cope with the relationship between what
> film can accept and what silver gelatine paper will print. For people
> who like this > working method it can work well.
>
One function of the zone system is to quantify the changes in exposure
and film processing that MAY be required so that the density range of a
negative will match the capabilites of a particular paper.

Another function of the zone system is to help SOME users previsualize
what they want their print to look like. It does this by breaking the
continuous range of tones into discrete shades of gray, called "zones",
which some people may find easier to visualize.

> 2. It is a complicated system.
>
It need not be. We have to be a little careful and not lump all of the
"zone" systems together. Ansel Adams generally gets credit for
developing the Zone System, but he obviously based his "discovery" on
what he and others had learned over the years about the relationships
between film, developer and paper.

Others like Fred Picker, Howard Bond and others have put their own "spin"
on what is called the Zone System and introduced new terminology and
techniques. However, most of these systems share a great deal with the
system that Adams described.

The Beyond the Zone System "system" described by Phil Davis is a major
departure from the work of others that came before him. They usually
introduced variables like lens flare, shutter speed errors and light
meter errors that may make what you are trying to measure less accurate.

Davis advocates contact printing the 21 step tablet onto the film you are
testing. This eliminates much of the sources for error in the testing
procedure. He says that you can estimate flare later or try to measure
it and adjust for it.

When you do a film test using the Davis method, you end up with five
films (pieces of roll film or sheets) that have been developed for
varying times. You can hold them up to the light and see what effect a
change in development has on contrast or you can read the steps with a
densitometer and plot the resulting curves. The interaction between
development time and film contrast is quite evident.

A paper test, using the Davis method, involves printing the same step
tablet onto photographic paper. If you usually print by contact means,
then you do the test the same way. If you normally enlarge your
negatives, then you enlarger the step tablet onto the paper. You end up
with several pieces of paper that represent your grades of paper or the
results of using variable contrast filters. After development, the
difference between paper contrast "gades" can easily be seen or
quantified by using a densitometer and plotting the resulting curves.

You can then easily measure the density range of what ever "grade" of
paper that you choose from the resulting graphs. This density range then
becomes the exposure scale that you'd like in your negatives to "match"
the characteristics of this "grade" of paper. This can all be done
graphically or the Phil Davis Plotter program will quickly do the
analysis for you once you punch in the numbers.

In the end, using the Phil Davis method you end up with a good
understanding of how your materials behave. You have the test negatives
and graphs that show the effects of development time on contrast and you
have the pieces of paper and graphs that show how paper contrast changes
with either grade or filtration.

All of this can be accomplished in just a few hours for either film or
paper. In addition, because the variables like lens flare, shutter speed
error and light meter error are eliminated, you don't have to retest your
materials if you buy a new lens. If you want to try new film, then you
need only test it and not of all combinations of it and the lens and
papers that you might use.

The PC-6 programmable calculator running the Phil Davis program isn't
required, but it makes the entire system easier to use.

Phil Davis also pioneered the use of what he calls the Incident System.
I won't go into the details of it, because my reply is getting too long,
but I think that it is something that students might find easier to
understand and use than the Zone System. With it, you think in terms of
the subject brightness range (SBR) and don't have any of the N-2, N-1,
N, N+1, N+2 terminology that can be confusing for new students. I use
this system for most of my photos and I'm very pleased with the results.

> 3. It is only one of many ways of controlling contrast. Many of the
> others are more simple and as effective and have been around for longer.
>
> 4.To suggest that controlling contrast through exposure and
> development is the zone system is analogous to suggesting that all
> dogs are chihuahuas as the chihuahua is a dog.
>
Obviously, photographers were making expressive prints before the term
Zone System as ever mentioned. In many cases, they did have to control
negative contrast and they worked out procedures or systems that worked
for them to do so.

> 5.Of course the zone system can be amended to cope with alternative processes.
> But there is no need to . The right choice of film, developer, exposure and
> development will give better results with less effort. That choice does not
> depend upon the zone system.
> If people wish to use the zone system for alternative processes because it
> suits there working methods and analytical approach that is their freedom.
>
I agree.
> 6. The confused logic and semantics of confusing the zone system , which is
> one of many ways of controlling contrast, with the overall principle
> has led to the zone system being taught as the only way of controlling
> contrast. This can be disastrous for students with a more empirical
> approach.
>
For many of us, the main way of controlling negative contrast (and
matching to our paper's characteristics) is via changing the film
development time. The Zone System or the Phil Davis Beyond the Zone
System approach allows us to quantify how we do this.

If your alternative process or something else like changing paper
contrast or using contrast changing masks (Howard Bond, Bob Pace) allows
you to make the expressive prints that you want to make without using any
of these systems than I'm happy for you. You or anyone else should use
whatever works for you and what you are comfortable with.

> 7. I report that professional printers I have known regard the zone system as
> being in the province of the anorak.
>
Huh?

> Terry King
>

Bill Patterson