Camera Film: Calibrating Black and White Negatives, Part 2

In Part One of our article, we detailed the first set of tests you need to run when calibrating your black-and-white film. In that exercise, you established your operating film speed, also known as your Exposure Index (E.I.). To recap, this process of calibration is based upon the following assumptions:

  • First, your Zone I is dependent upon your E.I. or exposure.

  • Next, the Zone V is set by development time.

  • And, lastly, Zone IX or X (nine or ten) is determined by developer dilution.

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At the end of Part One, you were to determine whether or not the step print four zones away (YOUR Zone V) from the one you found to be Zone I came close to gray scale card. We’ll begin this set of tests using the test prints from the last test.

Lay the test prints out again from darkest to lightest. Find your Zone I. That is the print which just begins to show texture above the total black. (You determined maximum black in the first set of test prints.) Now, count four more to the lighter end of the scale. This print should be Zone V. Compare it to the Kodak 18 percent Gray Card. Does it match? If not, find the test print that comes as close as possible to the Kodak Card. Is it one more than the predicted Zone V, or two more? Depending on the answer to this question, you’ll adjust development time in the next set of tests .

To raise or lower Zone V by one zone, increase or decrease development times 30-40 percent for 400 ISO films, 20-30 percent for ISO 100 films and 15-20 percent for 25-32 ISO films.

Let’s say you were testing Ilford’s Delta 400. Last time, you followed the manufacturer’s instruction and developed it for seven minutes. If you find that your #5 (YOUR Zone V) print is too dark, you’ll need to increase the development time. If your #6 print (YOUR Zone VI) looks like the Kodak card, you’ll need to raise Zone V one zone. So you’ll need to increase the development time from seven minutes to about 9 1/2 minutes. If the Kodak card falls in between your #5 and # 6, you’ll need to adjust one-half zone, so increase to only about 8 1/2 minutes. In the off chance that your #4 looked like the Kodak card, you’ll need to decrease your time by 30 to 40 percent. (However, in all the times I’ve done this test, I’ve never had to go that direction.) Write down what your new development time will be in your notebook.

Recheck your Darkroom Technique

Let’s take a minute to go over some important aspects of your technique. First, as I mentioned before, you must stick with a constant development temperature for all of the tests. It might be 20o C or 23o C. The precise temperature doesn’t matter as long you don’t decide to use another temperature. If you do use more than one temperature, your results will be meaningless, and you’ll have to start over. I’m reminded of a student who complained that his negatives showed more contrast in summer than in winter. When I asked him at what temperature he developed his negatives, he replied, ” Room temperature.” He always developed his negatives for the recommended 7 1/2 minutes. What was he doing wrong? In the summer, room temperature was close to 25o C; in the winter, it was closer to 20o C. In fact, he didn’t know what temperature he was using!. Of course, his results were always different.

The point is pick a temperature and stick with it. Choose one which will be easy to maintain year-round. I find it’s easier for me to heat my darkroom to 23o C, allowing all my chemicals to reach equilibrium with that temperature. Then I don’t have to worry about solutions cooling off or heating up during the course of my development process due to an ambient temperature difference. Please note: even if you start out with a solution at 20o C and the ambient temperature is 24o C, by the end of an eight minute processing time, your solution will no longer be at 20o C. This fluctuation introduces a variable which will throw your results off.

Many people try to solve the temperature problem by using water baths and automatic processors. But, in this discussion, I’m keeping the process simple and within easy reach of the average darkroom worker.

Determining a “Normal” Development Time

Now, back to our test.

Shoot another roll of film just like you did last time. Use the chart from Part One to plan your shoot. (This procedure should be in your notebook by now.) Please take care to use the same camera settings–even though your E.I. may have changed. Remember, you’ll shoot this roll at your new E.I., not the manufacturer’s ISO! This means you’ll have to move your lights either forward or backward to maintain the same camera settings. Don’t forget, your meter setting has changed. In other words, if you went from ISO 400 to an E.I. 200, you’ll have to move your lights closer in order to have your camera aperture and shutter speed settings match the settings in the chart.

Develop and print your frames exactly like we did before. After they’ve dried, lay them out. You should find that your Zone I is now where it’s supposed to be. Count four more to the lighter end (to YOUR new Zone V) and see that it’s different from the one from the previous test. See how it compares to the Kodak card. Is it closer? Do you need to make it lighter? Or have you gone too far? Don’t be discouraged if you’re still off. You may need to go through a couple of rolls of film before you come out right. Remember, this process is time-consuming, but it will pay off in better negatives, as well as better darkrooms skills.

When you finally get your preliminary zones right, you’ll be ready for the next step–setting zone IX (nine).

“Fine Tuning”

Looking at your second set of test prints, count eight steps from the Zone I step print. You’re looking for Zone IX. (Consult the above illustration.) YOUR Zone IX should be just slightly lighter than the test print for maximum white that you made last time. Is it? (It might even have a little texture in it.) If it’s more than one-half zone off, we’ll need to do some fine tuning–adjusting developer dilution.

If you feel like bailing out at this point, I don’t blame you. Some Zone System books don’t even address the possibility that you could need to do fine-tuning. It involves a lot of trial and error. Let’s go over the principles, so you can decide for yourself if the effort is worth your continuing..

Where you are now–that is, having set your Zone I with a new E.I. and having found a proper Zone V by selecting a suitable development time–you’re already way beyond most black-and-white film users. You should’ve achieved very noticeably improved results in your black-and-white negatives and prints. Many people will stop here, opting to make tiny adjustments using variable contrast papers or a lower or higher contrast grade of paper. If you decide to take that route, you should reprint your last set of negatives to see how they print at the new variable contrast setting or paper grade. Make sure that Zones I and V are still where they should be. If not, you may want to do another set of negatives in order to adjust development time to bring YOUR Zone V back into line. With the new paper, you’ll want to see how the Zone IX falls when the Zone V is corrected. In any case, be patient with yourself and the process.

Let’s say that in your test, Zones I and V are correct, but YOUR Zone IX is maximum white. You might be tempted to correct this by decreasing the development time a little. What will happen is you’ll lose Zone V. In theory, however, you can manipulate the dilutions of your developer to effect the ranges of Zone VII to Zone IX without effecting Zones I through V.

In the New Zone System Manual by White, Zakia, and Lorenz, the authors warn that you’re on your own at this point but suggest the following: If YOUR Zone VIII looks like a IX, try diluting your solution 100 percent. In other words, begin with your previous working solution and dilute it 1:1. In doing so, you’ll need to increase your development time by 25 percent. Experiment with the dilution and time combination until YOUR Zone IX is really Zone IX, while at the same time maintaining the lower zones.

You might find that YOUR Zone VIII is rendered a Zone VI. In this case, you’ll need to start all your tests over, using either a developer with more contrast such as HC-100 or a developer which can be mixed at stronger concentrations such as Rodinal. (In my original tests for Tri-X pan I found that switching to HC-110 solved my problem with MY Zone IX.)

In Conclusion

When teaching darkroom skills, I always begin with the exercises outlined in parts one and two of this article. These exercises provide a firm foundation of darkroom skills and help impart a clear understanding of how exposure and darkroom technique combine to produce a good print. Most students don’t have the desire or need to get into the fine tuning runs. Having learned the concepts of the processes involved, they can produce good negatives and avoid the bad habits many photographers get into when in the darkroom. I hope this discussion has helped you, and you apply these principles to make your black-and-white photos more satisfying.

by Michael Fulks

All written content (and most images) in these articles are copyrighted by the authors. Copyrighted material from Apogee Photo Mag should not be used elsewhere without seeking the authors permission.

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