Mastering the Zone System – Part 2: Film Testing

If you’ve not yet read the first part of our ongoing series on mastering the zone system, please do so here. And now, on to part two.

Many people view Ansel Adams as a rigid technician who condemned himself to a personal purgatory of endless testing, tweaking, and re-testing. When viewed in context with his life’s work, this theory doesn’t really hold up. The truth is, scientists aren’t typically lumped into the same group as artists. Those who hole themselves up in labs surrounded by analytical equipment usually aren’t overlooking grand vistas at golden hour or attempting to record a feeling onto an emulsion. No, Ansel was less of a lab coat-wearing-know-it-all and more of a Samurai practicing bushido. Perhaps a less dramatic likening would be that of a musician.

Starting in his childhood, Ansel trained to be a pianist. He was a rambunctious youngster and often had trouble following rules or focusing in the classroom, which had the result of getting him kicked out of several schools. The piano provided a sense of purpose and much needed source of discipline for little Ansel. He trained diligently and intensely for years and always planned to make a living as a concert pianist. It just so happens he was given a Kodak Brownie camera on an early trip to the Yosemite Valley. That box camera ignited a spark that would later result in the transition to photography as his life’s main endeavor.

In a recent podcast interview, Ansel’s long-time darkroom assistant (and now master printer and photographer in his own right), Alan Ross, said that for Ansel testing film was no different than playing scales on the piano. It is a repetitive, rather dull procedure that requires discipline on the part of the musician or photographer, but is of critical importance. Ansel didn’t gain his enjoyment from these forms of drudgery, but he wanted to control the technical aspects in order to freely pursue the creative. And this is exactly what I am advocating in this series; understand and control the technical aspects of your craft so that you can focus on your creative vision. Don’t get lost in the weeds, but arrive at a destination where technique comes naturally and gets out of your way. 

Now that you’ve had a pep talk, let’s establish some important elements to film testing. The name of the game here is consistency. In order to have valid, and more importantly, repeatable results, we have to remain consistent with everything surrounding our workflow. I will share my own personal results in this article to help illustrate the process, but please remember that these are my own results and yours will undoubtedly be different. 

First let’s go over some necessary equipment and procedures. You obviously need a camera – ideally you perform your testing with the same camera you will use to shoot with. Or if you’re like me and have a shelf full of cameras, pick the one with the most most reliably accurate shutter (I used my Nikon F6 for these tests). Next, you need a meter – use the one you will use for your Zone System metering (I used my Pentax Digital Spot Meter). Other useful items are a tripod, cable release, and a neutral-colored backdrop or poster board.

Next you need to decide what film and what developer you want to use. Use any combination you wish, but remember if you change either your film or developer down the road, you will have to complete the tests again. It is extremely important that you use fresh film. I tested Kodak TMAX 400, Ilford HP5+, and Ilford FP4+ in XTOL diluted 1+1. 

Finally you need something to measure the density of your negatives, and this is where it gets tricky. The obvious and most accurate way to measure density is with a densitometer, but few photographers have one. I am very lucky to have a densitometer built into my darkroom timer and enlarging meter (a highly recommended investment if you get serious about darkroom printing). You may also be able to find a used densitometer on eBay for a reasonable price or perhaps a friend or lab would allow you to use theirs. Other options are to use your spot meter itself or a transmission density step wedge for a visual comparison (see below). 

Testing Procedures

I recommend using 35mm film for testing, due to its economy. There’s no doubt about it, you are going to sacrifice some film here, but 35mm lets us get where we’re going faster. Feel free to use 120 or sheet film, but be aware that you’re going to burn through film. I encourage you to view this as an investment – the cost of two rolls of 35mm film is a small price to pay for the dividend of creative control.

Our first test is to determine film speed as well as point us in the right direction with developing time. Use the recommended developing time given by the manufacturer for this stage. Developing time is less critical for film speed evaluation than it is for highlight density so we just need to be somewhat close to our ideal time with this first test. I can virtually guarantee you will not end up using the manufacturers recommended times at the end of our testing. 

1. Set your camera on a tripod in front of a neutral colored backdrop, making sure that it fills the entire frame of your viewfinder. 
2. Manually focus your lens to infinity to throw the backdrop out of focus and remove any texture, which could influence the density on the negative. 
3. Set your meter one stop slower than box speed for the film you are testing (e.g. EI 200 for a 400 speed film) 
4. Take a blank frame with the lens cap on
5. Meter the background and make a Zone I exposure, followed by Zone V, and Zone VIII
6. Take another blank frame
7. Increase your meter’s ISO by 1/3 stop (e.g. EI 200 to EI 250). Re-meter the backdrop and make another set of Zone I, V, and VIII exposures followed by another blank exposure. 
8. Repeat until you have gone one whole stop above the box speed of your film (e.g. EI 800 for 400 speed film) 
9. Develop the roll according to the time listed in the film’s data sheet 

Tips for Metering

Make sure you are in the same light in which you intend to shoot. Film has different sensitivities to daylight and tungsten light. If you shoot primarily natural light pick a day with clear skies and set up in the shade for the most even illumination of your backdrop. If you are a studio shooter, use your normal setup of strobes or hot lights. Meter from the same angle as your camera and ensure that neither you nor your camera cast a shadow on the backdrop. 

A note about developing – remember that the objective here is consistency. Establish a routine and stick to it. Make sure you use the same thermometer for all your testing and subsequent use. Keep everything the same including whether you pre-wet your film, the way you agitate, whether you use a water or acid stop bath, and fixing time. 

Determining film speed – If you recall from the metering article, Zone I shows just the first signs of tonality, but no texture in the print. On the negative, Zone I is represented by the first sign of density above the clear film base (There is always some amount of silver that is developed spontaneously regardless of exposure to light; this is known as base fog. The measured density of the blank frame is referred to as film base plus fog, or fb+f and all subsequent densities are related to this base density). The exposure index or EI that gives us the correct Zone I density is our personal film speed. 

What is the “correct” density? It depends on your workflow and equipment. Generally speaking, condenser enlargers produce higher contrast prints than diffusion enlargers. Accordingly, the targeted densities are slightly lower for condenser enlargers than diffusion. If you intend to scan your negatives, I would aim for the diffusion density targets, as scanners don’t have the intensifying effects of a condenser enlarger. My enlarger has a condenser head so I am going for the lower densities in my negatives. 

	Diffusion enlarger or scanned negatives, Negative density above film base + fog	Condenser enlarger, negative density above film base + fog
Zone I	0.09 to 0.11	0.08 to 0.11
Zone V	0.65 to 0.75	0.60 to 0.70
Zone VIII	1.25 to 1.35	1.15 to 1.25
Approximate density range from Zone I to Zone VIII	1.20	1.10

(Table adapted from Adams, Ansel. The Print. Boston. Little, Brown, and Company, 1983. Print.)

Using my equipment and developing technique, I determined that my personal film speed for Kodak TMAX 400 is EI 400, Ilford HP5+ is EI 640, and Ilford FP4+ is EI 160. One of the advantages of using XTOL is the increase in effective speed of the film. I picked up 1/3 of a stop with FP4 and 2/3 of a stop with HP5, and got a true 400 speed from TMAX. Do not expect these results with most other developers. Manufacturers often overestimate the speed of their film and likewise overestimate the necessary developing time. Had I been using D-76 or HC-110, my speeds would have likely been slower than the manufacturers’ rating. 

As mentioned, 35mm film gets us where we’re going faster. In the same roll that determined our film speed, we also have Zone V and Zone VIII exposures for the film speed we determined to be correct. As you can see my measured densities were significantly over the target using the manufacturer’s developing time. Now I know I need to decrease my developing time. If your densities are lower than they should be, increase your developing time. Start by changing your time up or down by about 25% and then use smaller percentages as you hone in on the correct time. In order to do the developing test, we need to sacrifice another roll of film.

Determining Developing Time

1. Set your meter to the film speed determined from the first test
2. Using the same setup as before, make a series of Zone V and Zone VIII exposures followed by a blank exposure for the entire roll 
3. In a darkroom or changing bag, cut off a section of the roll and load it in a developing tank.
4. Rewind the remaining roll back into the canister or store in a light-tight container for subsequent tests
5. Develop the short section of film for the time determined from your results of the film speed test

Increase or decrease your developing time until your Zone V and Zone VIII densities are within range. This is your ‘Normal’ developing time.

The results of my tests are interesting and unexpected. Using three different emulsions at three different speeds, I arrived at the same development time of 8:00 minutes for all of the films at my targeted densities. This has the clear advantage of allowing me to develop any combination of these films in the same tank, which saves both time and chemistry. The manufacturers’ recommended times for TMAX 400, HP5+, and FP4+ in XTOL 1+1 are 9:15, 12:00, and 10:00, respectively. Again, my results are dependent on my camera, meter, development technique, thermometer accuracy, water chemistry, etc. I highly encourage doing your own testing, but feel free to use my times as a jumping off point for this method of metering and processing. 

An Overview of Expansion and Contraction

The next step in testing for Zone System processing would be determining times for expansion and contraction (referred to as ‘N plus’ or ‘N minus’ development). I have not included examples in this article as it is of limited utility to 35mm and 120 shooters because we are locked into the same processing time for the entire roll. This is where the major advantages lie for large format shooters; in addition to a huge increase in resolution from a physically larger negative, large format shooters can tailor their processing to each individual exposure in a process called expansion and contraction. 

If you recall from the metering method, we place our important shadow value in Zone III and measure where the other values fall along the tonal range. But what if we are shooting a high contrast scene and an important highlight value exceeds Zone VIII? We can either reduce our overall exposure with the result of a loss of shadow detail or we can limit our development to contract the tonal range. 

Likewise, if we are shooting in a very low contrast scene, placing important shadows in Zone III might place highlights in a flat and muddy Zone VI or VII. In this situation we could extend developing time to expand the tonal range and increase contrast. This process is similar to “pushing” and “pulling” but different in that we are utilizing increased or decreased developing times to manipulate contrast instead of allowing us to rate our film at a higher or lower overall speed. 

Can’t find a densitometer? Here are some alternative methods.

Spot Meter Method

1. Place your negative on a light table or other white light source (tablet or computer screen)
2. Take a reading from the blank frame (this represents film base + fog)
3. Take a reading from each of the Zone I exposures (Because each stop represents a density of 0.30, a reading that is 1/3 stop darker than the blank frame would be a density of 0.10 above film base + fog)
4. In order to determine developing time, Zone V should read 2-2.5 stops darker than the blank frame and Zone VIII should read 4-4.5 stops darker than the blank frame. 

Step Wedge Method

I recommend a 21-step transmission step wedge from Stouffer Graphic Arts. Each step represents a density increase of 0.15. The step wedge is an accurate way to visually identify the different densities and is relatively cheap. 

1. Place the negative and step wedge on a light table
2. The correct Zone 1 density should be equivalent to step 2 
3. Correct Zone V densities should fall between steps 5 and 6
4. Correct Zone VIII densities are between steps 9 and 10 

Conclusion

I hope you now have a better understanding of film testing and how development influences negative density. I know this is a very technical topic and like the testing procedure itself, is rather dull for those of us who just want to get out and shoot. On the other hand, I hope you see the power that comes from understanding and controlling your technique and processing. Having completed this testing we are free to shoot with confidence. We can now accurately meter a scene and more importantly, end up with a negative that reflects our vision perfectly!

In the next and final installment of this series we are going to bring this method home. From pre-visualizing a scene to metering, processing, printing, and presenting a final print, this is what this series has been working toward. It’s what I believe to be the most important aspect of photography. Gear is great and nerding out on historical or technical details is fun, but ultimately what matters is the print hanging on your wall. 

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