The Zone System

Learning goal

You will be able to decide, before pressing the shutter button, which gray tone every important area in a scene will sit at in the photo. You will explain how the grays stretching from black to white are divided into zones lined up one stop apart; remembering that the camera puts every surface it meters at middle gray, Zone V, you will move a surface to the zone you want by counting stops; when you place one zone, you will see in advance where the others fall; you will use this idea left over from the film era together with the histogram on today's camera; and you will decide yourself which zone a face will sit in, in a way that lets light or dark skin carry its own detail.

The question

In a blacksmith's workshop, you are photographing a smith working at the forge, where the flame burns bright red. The mouth of the forge is dazzlingly bright, the anvil and the walls are soot black, and the smith's face is half lit by the orange of the fire. When you point the camera at one place, the fire turns into a pure white patch; when you point it at another, the smith's face is buried in darkness. You don't know which setting is right, because you haven't yet decided which part of the scene should sit at which tone.

How did Ansel Adams manage the gray tones? Adams, together with the photographer and teacher Fred Archer, turned this decision into a system: placing every part of the scene, before the photo is taken, on a numbered step stretching from black to white. In this lesson we will talk about the logic of this method called the Zone System, how it works with stop calculations, and how it can be used today on a digital camera.

Context

In the exposure module we saw that the camera's meter tries to turn every surface into middle gray: snow darkened to gray, a black cat lightened to gray. With exposure compensation we learned to push this gray in the direction we wanted. In Lesson 11.7, on the other hand, we redistributed the grays of black and white in editing. The Zone System combines these two pieces of knowledge and carries the decision to before the shot.

The heart of the system is simple: the gray tones are a staircase and every step is a stop. What the camera meters is put in the middle of the staircase. If you know on which step of the staircase you want a surface to stand, you also know how many stops up or down you need to move it. The system was developed for film and black-and-white printing; but what makes it valuable today is this simple stop thinking.

Simple explanation

What are the zones?

The Zone System divides the tones stretching from black to white into zones and numbers each zone with a Roman numeral. In its best-known form today there are eleven zones: Zone 0 is full black, Zone X full white, and each zone in between is one stop brighter than the one before. The number of zones and their descriptions changed somewhat over the years in Adams's writings; to learn the system, the idea that the steps are lined up one stop apart matters more than these details.

In the middle of the staircase stands Zone V: middle gray, the tone the meter takes everything to. Zone III is a dark shadow whose detail can still be made out; the folds of a jacket, the bark of a tree trunk show there. Zone VII is a light tone whose texture can still be made out; the tracks on the surface of snow, the folds of a white shirt read there. Below Zone II and above Zone VIII are the ends where detail is gradually lost, approaching black and white.

How are previsualization and placement done?

The system begins with previsualization: before pressing the shutter button, you imagine how you want the photo to look. Should the inside of the forge be detailed, or the smith's face? Should the soot-black wall be completely black, or should its bricks be made out? These decisions decide which zone you will put a surface in.

Then comes placement. You choose the most important surface and meter it from a narrow area, for example with spot metering. The camera gives you the setting that puts that surface in Zone V, middle gray. If you want that surface to stand not in Zone V but in another zone, you add or take away as many stops as there are zones in between. If you want to place a detailed shadow in Zone III, you stop down two stops from the meter's setting; if you want to place a detailed light tone in Zone VII, you open up two stops.

Where do the other zones fall?

When you place one surface, the rest of the scene falls into its own place. This fall is decided by the brightness difference between the surfaces. If you placed the wall in Zone III and the smith's face is three stops brighter than the wall, the face falls in Zone VI. If the mouth of the forge is seven stops brighter than the wall, it falls in Zone X, that is, white without detail.

This calculation also tells you whether the scene fits into one photo. If the difference between the darkest and lightest surface whose detail you want to keep is bigger than the sensor or film can carry, you need to give something up, change the light, or take several frames and merge them. In the film era, photographers also widened and narrowed this difference with development time; on a digital camera, this job is done more by exposure, RAW and editing. Because clipped light tones don't come back in digital, many photographers prefer to first place the most important light tone in a safe zone and open up the shadows in editing; the histogram is the on-screen counterpart of this placement.

Which zone should a face stand in?

The camera's meter treats skin as middle gray too: if you take a reading from a dark face, the camera lightens it to Zone V and the skin looks lighter and paler than it really is; if you take a reading from a light face, the camera darkens it to Zone V and the skin looks darker and duller than it really is. Zone thinking lets you reverse this mistake: you decide which zone you want the skin to stand in, and depart from the meter's suggestion by that many stops.

There is no single right number for which zone a skin will stand in; it changes with the skin's own brightness, the light and what you want to tell. What matters is that the face stays among the zones that carry detail: dark skin shouldn't drop below detailed shadow and blend into black, and light skin shouldn't climb above detailed light tones and be erased into white. If two faces of different tones stand side by side, like a master and an apprentice, the brightness difference between them enters the calculation too; when you place one face, you need to look at where the other falls.

Visual evidence

You go back to the blacksmith's workshop. The smith is dark-skinned, with thick arms; beside them stands a light-skinned apprentice holding a hammer for them. You decide on your previsualization: the forge will be bright but not completely white, the smith's face will stand detailed in a warm darkness in the light of the fire, and the wall will be a dark shadow whose bricks can just be made out.

With spot metering you meter the smith's cheek, and to keep this face a little below middle gray, in a detailed zone, you stop down one stop from the meter's suggestion. With this setting the wall falls at the dark end of the zones, where the bricks can still be made out. The apprentice's face is about two stops lighter than the smith's and stands in the detailed light tones. The mouth of the forge falls in the top zones; on the histogram it comes close to the right end but doesn't stick to the edge. The same workshop, the same fire; what changed was deciding from the start where every surface would stand.

Common mistakes

Summary

The Zone System divides the tones stretching from black to white, in its best-known form today, into eleven zones; each zone is one stop, and Zone V is middle gray. Through previsualization you decide where you want a surface to stand, meter it and place it with as many stops as there are zones in between; the other surfaces fall into their own zones according to the brightness difference between them. In digital this thinking works together with the histogram; and which zone a face will stand in is decided not with a single number, but in a way that keeps the detail of light or dark skin.

Mini assignment

In this assignment you will work out a scene's zones in advance and make a placement.

1. Choose a scene with bright and dark surfaces; with spot metering, meter at least four surfaces separately and write down the stop differences between them.
2. Choose the most important surface and calculate how many stops to depart from the meter's suggestion to place it in the zone you want.
3. Shoot according to your calculation, and check where the other surfaces fell with the histogram and by magnifying.
4. Photograph a face first with the meter's suggestion, then placing it in a zone you chose yourself, and compare the two frames.

Check yourself

• From the stop differences between surfaces, were you able to predict whether the scene fits into one photo?
• Did the surface you placed come out in the photo at the tone you had in mind?
• On the face you placed, dark or light, can the eyelid and the line of the lips still be made out?

Glossary

Mini quiz

1. Which zone does the camera's meter put a surface it meters in?

• A) Zone 0
• B) Zone III
• C) Zone V
• D) Zone X

2. To place a detailed shadow you metered with spot metering in Zone III, what do you do?

• A) You stop down two stops from the meter's suggestion
• B) You use the meter's suggestion as it is
• C) You open up two stops
• D) You stop down five stops

3. If the wall was placed in Zone III and a face is three stops brighter than the wall, which zone does the face fall in?

• A) Zone IV
• B) Zone V
• C) Zone VIII
• D) Zone VI

4. What happens if you meter a dark-skinned face directly and shoot with the meter's suggestion, and what do you do?

• A) The face falls to black; ISO is raised
• B) The face lightens to middle gray and looks pale; you stop down from the meter's suggestion according to the zone you want
• C) Nothing happens
• D) The face is erased into white; the white balance is changed

Answers

1. C — The meter tries to move every surface to middle gray, Zone V in the middle of the staircase.
2. A — From Zone V to Zone III is two steps down; each step is one stop.
3. D — Three steps above Zone III is Zone VI.
4. B — The meter lightens dark skin to the middle; for the skin to stand detailed and in its own darkness, you go below the suggestion.

Summary card

• The tonal staircase: Zone 0 black, V middle gray, X white; each step one stop.
• See first: which surface will stand at which tone?
• Meter and place: however many steps from Zone V to the zone you want, that many stops.
• The others fall: from the stop differences, see whether the scene fits.
• Keep the face in detailed zones; there is no single number for every skin.

Bridge to the next lesson

You decided every gray of the blacksmith's workshop from the start; on your screen the photo looks exactly as you planned. Then you open the same file on your phone, and the orange of the fire is flatter, and the smith's face a slightly different color. Why does the same file give two separate images on two screens? The next lesson talks about color profiles, which color space is written inside a file, and how to prepare a photo for the web or for print.