Camera Film: Calibrating Black and White Negatives, Part 1

Exposing B/W film so you don’t end up with flat, thin negatives can be a challenge. While a bit involved, my technique has saved me considerable money and time in the darkroom. The following is Part One of a two-part article:

Step One: Determining the E.I. of Your Film.

Step one will help you determine the Exposure Index (E.I.) of your chosen film. The E.I. is the “true” speed of your film, based on your camera meter and your processing technique. When you’ve finished working with this step, you’ll have a new ASA or ISO to which to set your meter.

Exposing the First Test Roll

What you’ll need:

Film: Decide on a film and stick to it. If you’re new to the eccentricities of black-and-white photography, I’d suggest Ilford’s Delta 400. Other good choices would be Tri-X, Neopan, or Agfapan. Stay away from the T-max films for now. They don’t respond well to this method of calibration. You’ll need at least five rolls of twenty-four exposure for this exercise. I strongly recommend you buy all your film from the same lot number. This will eliminate the possibility that the film will vary from roll to roll.

Another way to avoid film discrepancies and save a lot of money as well is to buy your film in thirty meter or 100 foot rolls and load your own. (This is the method I prefer, especially when I’m shooting 100 feet of film a month.) If you do load your own, load only twenty frames at a time. Shorter rolls will guarantee even development from the beginning of the roll to the end. We’ll discuss why later.

Camera: You’ll need a camera with a full manual shutter and aperture controls, one in which you can override the ISO setting. Shutter speeds are notoriously inconsistent. Usually, you can count on the 1/15, 1/30, 1/60, 1/125 shutter speeds on a mechanical shutter to be fairly accurate. Speeds faster than these are the first to lose accuracy. If we go slower, we begin to suffer from reciprocity failure on some films. If you’re in doubt about the accuracy of your speeds, have the shutter checked out.

Notebook: You’ll need to keep careful notes throughout this process. A three-ring notebook will help you organize your notes along with your test negatives and prints. Record-keeping is very important, because you will need to refer to your previous findings from time to time.

Lights: You’ll need simple flood lights: 4800K 250W lamps are recommended. They can be purchased from a camera supply shop. Clamp-on flood lamps from the hardware store will suffice to hold them. Just remember, these lamps become extremely hot, so don’t leave them on for very long and don’t leave them unattended. They can easily cause a fire!

Black cloth: The cloth will create a background for your target. An ideal fabric for our purposes is black velvet, but any non-reflective material will work fine. It should be roughly two by three feet in size.

18% gray card: This card should be an integral part of your tool box, as it comes in handy for a number of purposes.

Terry cloth: You’ll need a piece of fabric about the size of a wash cloth in a tone which is as close as possible to the tone of the 18% card.

Before we begin the actual exposures, let’s plan our photos. In your notebook, prepare an exposure chart like the one that follows:

Calibration Exposure Record

Film

Developer

Film Speed Index

Frame	Exp. #	Zone	f-stop	Shutter	Subject
1	1	0	blank	Len’s cap
2	2	V	5.6	1/60	Gray card
3	3	I	16	1/125	Textured
4	4	II	11	1/125	“
5	5	III	8	1/125	“
6	6	IV	8	1/60	“
7	7	V	5.6	1/60	“
8	8	VI	4	1/60	“
9	9	VII	4	1/30	“
10	10	VIII	2.8	1/30	“
11	11	IX	2	1/30	“
12	12	X	2	1/15	“
13-end	13-end	V	5.6	1/60	“

In this chart, I’ve provided exposure settings for your camera. It’s important that you follow these settings precisely.

Pin or tape the black cloth to a wall, and center the gray card in the middle. Arrange your lights so that they illuminate the gray card evenly. Place one light on each side of the camera at an angle about forty-five degrees off the plane of the wall. They should be equidistant from the target.

Set your camera meter at the manufacturer’s ISO rating for the film you’re using. Being careful not to block the light, fill the view finder with the gray card and take a meter reading. You’ll need to adjust the lights forward or backward until the camera meter reads: 1/60s @ f5.6. Do not adjust your camera in any way–only the lights. Make sure the card is evenly lit. THIS IS VERY IMPORTANT!

Load your camera with film. Leaving the lens cap on, fire the shutter and advance the film until you reach frame number two. This early frame receives no exposure and will give us a zone 0. Please note on your calibration record that you have just taken frame #1 and are ready for frame #2.

Set the camera on a tripod, and set your lens focus to infinity. Move the camera back and forth until the gray card completely fills the viewfinder. Be careful not to block your lights. Expose frame #3 as indicated on your chart.

Replace the card with the terry cloth. Repeat the steps you took above until you obtain a 1/60s @f5.6 when metering on the terry cloth. This time, fill the frame only 2/3 with the terry cloth, leaving some of the black background visible in the view finder. Also, this time focus on the terry cloth. Now complete the exposures as outlined on the record. (You’ll note that the exposure of frames 13 until the end should be 1/60s @ f5.6. This will give the remainder of the roll exposures which simulate a scene containing an equal number of tones.)

Now you’re finished with the exposure part of this step.

Development

Obviously, I’m assuming you’ll develop your own film using your own paper. However, this process can be done through a commercial lab, but it might be a little expensive and time-consuming.

What you’ll need:

A small film tank: For 35mm film, the tank should hold at least 250 ml of fluid; for 120 film, at least 500ml. Remember I mentioned that the roll of film you load yourself should be kept to twenty-four exposures or shorter. The development reels for small tanks are the reason. When a roll is loaded onto the reel, it’s wound more tightly as it approaches the center of the reel. A thirty-six exposure roll, when loaded onto the reel, will have one end of its roll exposed to more developer than the other. Thus, by keeping the roll shorter, you can expect more consistent results from your work.

Developer: Always use fresh developer. Even though the manufacture may boast that you can develop three rolls in 250 ml of developer, DON’T DO IT! Don’t use replenished developer, either. These precautions may increase your costs slightly, but they’ll result in consistent, repeatable results. An easy way to insure safety is to use a one-shot developer such as Rodinal, and throw out the used portion after each application.

Printing Paper: The object is to come up with film that can be printed as simply and easily as possible. For these tests, choose a medium-contrast, glossy, double-weight paper. You can use a multi-grade paper for these tests. However, be sure to set your enlarger’s filter to print on either a two or three paper grade, and leave it there. Because paper varies greatly from lot to lot, I’d recommend buying your paper in 100 sheet boxes. Once you get calibrated to the medium-grade paper, you’ll need to purchase only small amounts of paper in other grades.

Print Developer: Just as with the film developer, the print developer should be mixed from stock just prior to use and discarded afterward. Again, always start with fresh developer. One liter of working solution should be sufficient to compete this test.

Load your exposed film into the tank. Determine your total development time, based on the manufacturer’s suggestion found either on the developer bottle or the film insert. Please note: this time is based on a specific temperature. This is very important! What it might say, for example, is “7.5 minutes at 20o C.” As the temperature goes up, the development time must be shortened. As the temperature falls, time is lengthened. Try to standardize your technique so that you always use the same temperature. Consistent temperature will cut down on your calculations and prevent errors caused by miscalculations. For me, I’m standardized on a slightly higher temperature–about twenty-one degrees Celsius. It’s easier for me to heat a solution to a certain temperature than to try to cool it. Sometimes, regulating the heat is as simple as raising my darkroom temperature to twenty-one degrees C and letting my solutions equalize at that temperature. In the summer time, I can never get my room temperature and solutions to twenty degrees C, except early in the morning. Just remember, when standardizing your technique, your development time should never be shorter than five minutes. Less time will result in uneven development.

After you’ve loaded the film and poured in the developer, agitate briskly for thirty seconds. It’s recommended that you use an inversion style agitation, which means you completely invert the tank for about a second and then right it, repeating this procedure for about thirty seconds. Rap the tank on the floor or table top to dislodge any air bubbles that might cling to the film. The inversion method is preferable to the rotation method of many tanks–in which the film is turned within the developer. Because the film is on a reel, mere rotation may not provide even development across the whole length of the film.

Continue agitating for ten seconds of every subsequent minute. You may notice that this instruction is different from Kodak’s recommendation. Tests have shown that this stratagem results in sharper negatives.

When the development time is up, use a water bath to stop development. I prefer to avoid regular stop bath solutions, as they’re very harsh on the delicate gelatin surface of the film. I’ve seen instances in which bits of the emulsion have been damaged. Plain water is sufficient to stop development and far less hazardous.

Fix and wash according to the directions of your fixer manufacturer. Dry.

Printing the Film

To print a calibration negative, a standard printing time is required. This times takes into account variations due to enlarger, film and printing paper characteristics. It’s defined as the minimum exposure time needed to render a Zone 0 (film base) negative a complete black on any given paper.

To determine your standard printing time, set your enlarger height to whatever distance you need to create whatever size enlargement you most commonly make. If you don’t know what size enlargement to choose, simply set your equipment to make an 8 x 10 from the full frame of your negative. Record this setting in your notebook.

Insert frame #1 (the blank negative) into the enlarger. Focus, using the edge of the negative carrier. You probably won’t see any grain to focus with a grain focuser. Set your lens aperture at your favorite aperture. If you don’t have a favorite, set it at f 11.

Now make standard black-and- white patches. These will show you the maximum black-and- white of which the paper is capable. Expose a 4 x 5 piece of paper for one minute. If you’re using fiber base paper, develop this for three minutes at twenty-one degrees C with constant agitation. During this calibration exercise, and indeed for all of your printing, don’t cut your time short. However, if you’re using RC paper, make this time two minutes.

Now take a 4 x 5 piece of paper and stick it into the developer without exposing it. Develop, stop and fix, as we’ve detailed above. When fixed, wash and store the paper in fresh water.

Next, with the easel centered under the enlarger, make a test strip on another 4 x 5 piece of paper. Expose the paper in five two-second increments, covering up one inch of the paper after each exposure. When you’re done, expose the whole piece of paper for an additional four seconds. This “step wedge” will thus have exposures of six, eight, ten, and twelve seconds. Develop, stop, fix and wash.

If the result is a paper that’s all grays and no black, open the enlarger lens one stop and try again. If the result is all black, close the lens aperture one stop and repeat. Eventually, you should get a piece of paper with bands of gray that go completely black. Examine the print in bright light–such as with a 100 watt bulb about fifteen inches away. Find the first band that’s completely black and is the first one adjacent to a strip that’s not quite black. This black band represents your standard printing time. Record the time it took to expose this band in your notebook.

Expose another 4 x 5 sheet of paper at this exposure time and process. Now expose all the other frames using exactly the same time and processing technique. Do not deviate from this time and technique. This is very important. Do not take any shortcuts. Print ALL of the frames from 1-12. It will be helpful to identify each successive print with a soft pencil as you put it in the wash. Label them “frame 1,” ” frame 2,” etc. This will help you in the next step. Wash and dry all prints.

Evaluation:

Lay your pictures out in frame order, from black on the left to white on the right, in a good viewing light. Your prints should range from black to white–maybe only black to light gray. (Don’t worry, we’ll fix this later!)

To begin, find the two Zone V frames. This should have been frame two of the gray card and frame seven of the terry cloth. By definition, these should be the same. Squint a little and see if they are. If they’re more than slightly off, it means you made a mistake somewhere–probably in metering–and you’ll have to repeat the whole process.

If you’re close to having a perfect match, then go to the next step. Under direct light, find the first piece that’s just slightly lighter than the first maximum black print you made. This is Zone I. Turn it over and find out what frame number it was. Looking in your notebook, find out what Zone it should have been. If that frame was Zone I, your meter setting was correct. If not, you’ll need to make a correction.

Let’s assume your meter setting was off– which, in all likelihood, it was. What do you do? If, according to your log, the frame was supposed to have been a Zone II, but it’s actually just slightly lighter than total black or Zone I, adjust your ISO setting on your meter to ½ of the original ISO setting. If you’re testing a 400 ISO film, then the new setting would be ISO 200. If, according to your log, the frame was supposed to have been a Zone III, but it is black or slightly lighter than black, then you’ll have to set your new ISO to ¼ of the original. If your film was a 400 ISO, then the new ISO will be 100. If you began with a 100 ISO film, then ½ would be 50, ¼ would be 25.

It’s not likely that you wouldn’t find a Zone I and would have to set your ISO the other way–namely to a higher value. We most often find that manufacturer’s ISO are set a little higher than they truly are. For example, when shooting Tri-X, my E.I. is 200.

Having found your Zone I card, now count four frames to the right. This should be what your new Zone V is, once adjusted for exposure. Compare it to the card. If it’s lighter, you’ll need to decrease development on the next run of tests. If it’s darker, then you’ll have to increase the development time. To raise or lower Zone V by one zone, increase or decrease development times 30-40% for 400 ISO films, 20-30% for ISO 100 films and 15-20% for 25-32 ISO films. Calculate what your new development time will be, and write it in your notebook. You’re now ready for the next set of tests.

My experience is that even if you go only this far in determining the exposure index of your film, your pictures will probably improve 100%. I know mine did. I went from flat negatives, to negatives that yielded rich blacks and whites. The process also forced me to improve and standardize my technique, which had the added benefit of saving me both time and money. The next step in our calibration series will help you refine your development process even further. Look for it in our next installment.

by Michael Fulks