Welcome. These are resources to help you conduct and analyze film tests. Testing film is like playing musical scales. It may not be the most exciting activity, but in the end, the results that appear in your regular work make the effort worth the trouble. Accomplished musicians continue to practice their scales. Accomplished Zone System photographers continue to conduct and update film tests.

• Graph paper
  Print this page if you want to hand draw graphs of film densities. The grid is specially set up just for the Zone System graphs.
• Graphing app
  Use this application to automatically graph and label your film test results. It is fast and accurate.
• Graphing app with sample data added
  This is the same form as the one above, but it has sample data already entered into the form elements.

Film testing procedures

The process described below is somewhat idiosyncratic to the author's situation. I had to get classrooms of people through a thorough set of film tests within one semester. We used, and I recommend that you use, bulk loaded film cut to 12-exposure lengths. A 100' roll of film should make at least 50 12-exposure rolls. Each roll received a total of 12 exposures:

• 1 exposure of a hand written paper noting which film and development are being tested on this roll.
• 1 exposure with the film cap on to help determine film base plus fog levels
• 10 exposures to test for density

Film base + fog is the density that 'clear' film has after development. The densitometer has to be adjusted for each roll of film so that the film base + fog doesn't throw the other measurements off. A small inaccuracy in film speed leads to very inconsistent results at higher densities.

The film edge cannot be trusted for film base + fog readings. It is frequently darker than actual film base. The clear frame created by exposing one frame with an opaque lens cap covering the lens serves to establish film base and to mark the beginning of the other exposures.

Before you can plan a series of film exposures, you must have a set of target zones and densities. The target is a combination of exposure and density. For all film tests, Zone 1 is the target zone for filmspeed. The target density for Zone 1 is generally accepted as .1 to .12. Because of the nature of film, it is necessary to establish that density at a Zone 1 exposure to establish your filmspeed. Any test which does not produce a Zone 1 density at or extremely close to the range of .1 to .12 cannot be accepted as a useful result.

Later some of these definitions become a bit more arbitrary than the paragraph above suggests, but do not use that as an excuse to allow a density of other than .1 to .12 to slip through your film tests. Each film test, whether engineered to test for film development or for film speed, must include a confirming film speed test. Film speeds shift *slightly* with variations in development.

The target zone for normal development should be Zone 8. There are other ways of doing it but we will use Zone 8. In the instance of normal film development, a Zone 8 exposure should have a film density of 1.2 to 1.25 if you are using a condenser enlarger. Most people use condenser enlargers; if you don't know your enlarger type and your enlarger is not a color enlarger, then assume that you are using a condenser enlarger. If your enlarger is a color enlarger and you do not know whether or not it is a diffusion enlarger, then assume that it is a diffusion enlarger. If you use a diffusion enlarger, a good target density for Zone 8 is about 1.3 to 1.35. For the purposes of this material assume that you are testing for a density of 1.2 at Zone 8 for Normal development.

To test film for normal development you have to produce a bare minimum of two exposures:

• Zone 1
• Zone 8

and those exposures have to have very specific film densities. The values below are typical.

• Zone 1 -- .09 to .12
• Zone 8 -- 1.2 to 1.25

If either of those densities is wrong, the film test must be redone.

The extra exposures, a bracketed set of 5 exposures for each target, will help diagnose film tests and also help estimate the values for the next set of exposures and development times. The set of five bracketed exposures helps confirm the validity of the primary exposures. Each film speed test should have two densities less than .1 and two densities greater than .12. If that isn't the case, then even if the target exposure was correct, the result is highly questionable and should be repeated.

Ditto for the target density on the other end of the scale. So in fact, before test can be accepted, it should have 10 exposures in correct relationship to each other. A film test that doesn't have that set of relationships can look right but be wrong.