The Tone System of Negative Exposure, Period
Redefining Fundamentals
by Gene Kennedy ©1998
Not long ago, surrounded by musicians, I was reminded of all those music/photography analogies we photographers have been provided for years (“The negative is the score; the print is the performance,” for example). I was also struck by a significant difference: whereas musicians, from the very beginning, identify and learn the tones of the musical scale in order to make music, most of us, as beginning photographers, learn blind faith instead of tones and are told to trust automated cameras and match-needle meters to guide us in the single most important aspect of our medium –– exposure. Some time later, when we’ve progressed to “advanced,” some of us find our way to the mythical and esoteric *Z*O*N*E* *S*Y*S*T*E*M*, at which time we are finally granted clearly-defined access to the tones of the photographic scale.
For students, who wouldn’t necessarily choose to go to the Zone place, the response to this sudden revelation of the keys to the photographic universe is mixed. A few actually realize that this simple 11-step gray scale gives them a handle on the tools to expose their film with accuracy and consistency. At least as many, having enjoyed unrestrained adulation from mothers and sweethearts for the pictures they’ve made with cameras on autopilot, are not about to give up their creative accomplishment to some overly-methodical, anal-retentive, spotmeter-driven “System” connected primarily with old-fashioned nature scenes. Still others, enthralled by newly-found controls, turn to “plus” and “minus” development as the answer to all their prayers and make it the overriding element of their photographic lives. Somewhere in this process, what often gets lost is the most important reason for the “system of zones:” the determination of correct exposure.
Let’s go back to the music analogy. As a child, you might easily have begun piano lessons at age seven or eight. Spread out before you were the 88 black and white keys that are used to produce the notes of the piano’s tonal scale. Do we trust you, the seven-year-old, with all those tones? Absolutely. How else can you learn to control this tone-making tool for the purpose of expressing the emotions and ideas contained in music? Do we practice the same level of trust in photography? No.
Virtually all of us, as novice photographers, start out with cameras containing light meters that tell us either “RIGHT” or “WRONG” on every picture (or else “Leave me alone –– I’ll take care of this”). Although you may hear about an infinite scale of tones from black to white that is to become your palette, you are generally not told how to achieve those specific tones. Once you learn that the one-stop steps on the logical-looking shutter speed dial are equal to the one-stop steps on the illogical-looking aperture scale (You did learn that, didn’t you?), a window of opportunity opens briefly, but then closes, because neither your camera instruction manual, nor the film data sheet, nor your photo teacher (if you have one), are willing to shed any light on how to produce a specific quality of light or dark in a specific area of a photograph. And, since light meters are wrong far more often than they’re right when metering entire scenes, what usually follows are rolls and rolls of badly exposed negatives. Blind faith in camera meters, general light readings, and manufacturers’ exaggerated film speed ratings result in months or years of error and frustration. Eventually, bad experience leads to band-aid solutions to overcome repeated mistakes, but without any real understanding of how to produce specific tones with the tone-making tool. What gets lost is the ability to predictably create the “notes” necessary for description or expression with the medium of photography. Why don’t camera and film manufacturers trust you with the “keys” you need to produce the notes of photography’s tonal scale? Perhaps they think (know?) that you don’t want to be bothered with all that control. If the piano lessons you endured as a kid just made you want a player piano, and a fully automated, multi-program, auto-focus camera, with the new auto-composition mode, you can stop reading. If not, let’s go back to that window of opportunity...
Do you know what your light meter means when it says “RIGHT?” It means MIDDLE GRAY; a specific gray tone, pretty dark, that represents the middle of the photographic gray scale. It’s called Zone V in the Zone System and it can be purchased in the form of a standard photographic gray card of 18% reflectance, or it can be closely approximated with an inexpensive piece of mat board of the same tone. What good is it? It tells you what result you’ll get if you meter anything and follow the meter’s advice. Get one. With that single piece of reference information, and your understanding of those one-stop steps on the shutter speed dial and aperture scale, you are ready to look out through that window of opportunity.
What’s at the window? It’s the same 11-step gray scale that came with flashing colored neon lights and dressed up in capital letters and stars as the *Z*O*N*E* *S*Y*S*T*E*M*. To begin with, however, we don’t need the “System;” we don’t even need the capital letters or the Roman numerals; all we need are the zones (tones) and their numbers –– a simple, unassuming set of names for the eleven steps on the scale. It’s not even a particularly good set of names, but it’s already established, so let’s stick with it. There’s nothing advanced or esoteric about these zones (tones). They just give us a place to start learning the steps of the scale.
If you’re thinking “I can’t handle all this complexity,” remember the seven-year-old at the piano, with the 88 keys. Is it really true that you can’t handle eleven steps, neatly separated by one-stop intervals? I don’t think so, because it’s been proven over and over that the easiest time to learn the zone scale and its easily accessible individual tones is right at the very beginning, before you develop any bad habits. And to make sure that we don’t get it all confused with the complexity of the Zone System, let us simply call it the tone system of exposure, period (no capital letters, no stars; sort of like saying god instead of God). There’s obviously more to learn, but let’s leave that for later; this is only about exposure (the most important step in the entire process). Changing from “Zones” to “tones” will not alter the fact that everything about the tone system of exposure, period, is consistent with the Zone System of Applied Photographic Sensitometry, as well as other systems of scientifically demonstrated overkill.
Here are the tones of the scale, and how to produce them:
Highlight Values
Tone 10: Pure white of the paper base. Achieved by giving five stops more exposure than the uninterpreted reading of a selected (usually white) area (Five stops more than tone 5 equals tone 10).
Tone 9: Just barely darker than the white of the paper base; a slight tone but without texture. Four stops more exposure than the uninterpreted meter reading of the selected area.
Tone 8: Very light gray that reads as white with delicate texture. Think of sunlit snow. You can make it tone 8 by metering the snow and then giving three stops more exposure.
Tone 7: Light gray but with full detail. I am thinking of very fair-skinned people and concrete. Meter the selected area and increase the exposure by two stops.
Middle Values
Tone 6: Medium light gray. Most commonly cited as the correct tone for Causasian skin. Probably closer to what we think “middle gray” should look like. Meter the area that you want to be tone 6 and give one stop more exposure. Here’s an example of one of those experience-generated “band-aids:” Portrait photographers have always known to meter Caucasian skin and give one stop more exposure, even if they never heard of the Zone System.
Tone 5: Middle gray. This is the tone you get when you follow the advice of an uninterpreted meter reading. Look at your gray card, compare it to the subject in question, and ask yourself “Do I want this object to look this dark?” If you compare the gray card to the entire scene, you will find that you would very rarely want the overall picture to be as dark as tone 5. Check it out; it’s pretty dark!
Tone 4: Dark gray. This is my most frequent exposure-determining placement, which I use for open shadows (for example, my own shadow, or the shadow of a building or a tree in an open landscape). After metering the shadow, reduce the exposure by one stop.
Low Values
Tone 3: Very dark gray; actually used to describe things that you want to look black, but with full detail. This is the most critical tone for exposure because it is the darkest placement you can make and still retain all the texture and detail in an area. To achieve tone 3, you meter the area (usually a deep shadow or very dark material) and give two stops less exposure.
Tone 2: Black with a hint of texture. So dark that you only get a suggestion of surface texture, not full detail. Never place something this low unless you know that you will never want full detail in that area. An area placed on tone 3 can always be printed darker, but an area that does not contain full detail in the negative cannot provide it in the print, even if you print it lighter. Tone 2 can be produced by metering the specific area and reducing the exposure by three stops.
Tone 1: Textureless black in the print. Just barely distinguishable from tone 0 because it represents the first printable step in negative density, which is tied to the exposure index (or speed) of the film. If you want your mother-in-law, standing on the beach with the sun behind her, to be a silhouette, just meter her shadowed figure and close the lens four stops. Presto! — She’s gone.
Tone 0: Pure black. The print tone produced by clear, unexposed film. Five stops less exposure than an uninterpreted meter reading. As far as I know, tone 0 is of no practical value to photographers taking pictures. It is obviously of interest to the sensitometrists, but that’s another story for another time.
So, now you know the names of the steps of the gray scale. What are you going to do with them? There’s no need to read further unless you’re willing to make a commitment to a couple new steps in your picture-taking process. Before going into that, a word about film speed (ASA or ISO) is in order:
If you ever get involved in the Zone System, you will have to endure a testing procedure for the calibration of the exposure index for whatever film you use, in your camera, with your developer, etc. Sadly, for all of us, but especially for film manufacturers who exaggerate the speeds of their films, the corrected speeds for most films is about half their ISO or ASA numbers. Until you’re ready to perform that test, the best thing to do to assure adequate exposure using the tone system is to set your camera’s ISO setting at one half the rating provided on the film. Films of 400 ISO should be set at 200 on the ISO/ASA dial, 100 ISO films should be set at 50, etc. Your own results may suggest that you make an additional correction, one way or the other, but this is a logical starting point.
The first habit you must develop, if you want to succeed at producing specific tones (and predictable exposures) is that of taking selective light meter readings of specific areas. That simply means getting close enough to fill the metering area of the camera with the single area of brightness to be used for pegging the exposure. This is easy enough for most people to understand, but not so easy to get them to do. You will see this as more work, but you must remember that metering the whole picture area will give you the wrong exposure most of the time. In fact, if you can learn to meter intelligently by placing specific areas on specific tones, you will soon find out that exposures work out to be the same in similar situations and that you can actually spend less time metering and more time paying attention to the subject. It’s a wonderful revelation to know that metering for a place is perfectly adequate; the payoff is that you don’t have to meter for every picture, leaving all your attention for selecting, framing, and timing the next image or images.
The next piece of discipline you will have to accept is that of making decisions about where on the scale to place those selected areas, after you meter them. At this point, for virtually all your pictures, you need only to be concerned about six steps of the gray scale, from tone 3 (black with full detail) to tone 8 (white with delicate separation). If, as a general rule, you take care of the shadows first, you can almost get by forever with tones 3 through 6, with tones 3 and 4 being the most commonly used. Sometimes, however, when contrast is very low, it is better to meter the lightest thing in your picture and make placements on tones 7 or 8.
It is important to understand that all of this is under your control. You can meter any area of a scene and place it anywhere you want on the scale. What you can’t do is change the relationships between light and dark things in a picture (except in cases where filters can change tones); light objects will be lighter than dark objects. If, for example, you decide to put a black leather chair on tone 7, everything lighter than the chair will be pretty well blasted-out-white. (Ordinarily, you would only put a black chair on tone 7 by accident, but it is possible to do it on purpose, if it that meets your needs.) The most critical piece of information is this: if you make sure to expose adequately for the darkest parts of your picture, it absolutely guarantees that everything else will be recorded on your film as well. The best general approach is to expose the film so that subject areas are placed pretty close to what we would call literal representations, and then to use the printing process for creative interpretation.
As I write this, I can hear you shrieking “But what if the contrast is too high — won’t I lose the highlight detail?” Unless you are shooting in extreme conditions, the answer is no. If you use long-scale films (such as any ISO 400 film, or Ilford FP4-Plus, to name one medium speed film), you can be assured that very bright areas (even though they may be off the normal scale) will still be separated by the film and can be retrieved during printing, either by lowering the contrast or by burning in. Trust me on this; the combination of exposing for specific tones, on long-latitude film, will produce consistent, information-rich negatives that will print more easily, with much less need for dodging and burning. If you insist on using slow, fine-grained films (which have a short exposure scale or latitude), you might indeed lose the highlight detail by what is known as “blocking.”
In conclusion, if you can learn this much about exposure, and learn it well, it’s all you need to make you competent, and it puts you in control of the camera instead of vice versa. Then you can get down to the real issues of picture making, without the worry that every exposure is a gamble. At the same time, it is true that there is plenty more to learn about film’s response to exposure and development, and more advanced study can take you into all the ramifications of applied sensitometry, characteristic curves, plus and minus developments, etc. The important point here is that these topics are perfectly consistent with and build upon the foundation already laid down and described above. Consequently, the more advanced controls do not require a relearning of the fundamentals of exposure; you can move forward instead of having to back up and start all over again.
