Exposure compensation

Learning goal

You will be able to use exposure compensation as the fastest way to tell the camera the scene's tone. You will read the range and the steps of compensation, notice before every shot whether the compensation indicator is at zero, see the result before shooting on screens that have a live preview, tell when to turn to manual mode because the light is constant and when to turn to compensation because the light is changing, know that different metering modes ask for different amounts of compensation in the same scene, and keep a face's tone steady when photographing the same person in front of changing backgrounds by changing the compensation according to the background.

The question

In the previous modules almost every lesson turned to the same small button: plus in snow, minus against a dark background, plus in front of a bright window, minus in front of a dark floor. On many cameras this button marked with plus and minus sits right under your thumb; on a phone it sits in a corner of the screen as a small sun icon.

Why does that small +/- button matter so much? Because however clever the camera's metering is, it doesn't know the scene's real tone; compensation gives the camera that information with a single touch. In this lesson we will treat compensation not as a rescue tool but as a constant part of shooting, and talk about when to prefer it to manual mode and how it works together with different metering modes.

Context

You first met compensation in Lesson 3.5: a button, a dial, and not forgetting to turn it back to zero when the scene changes. In the exposure module you saw that every EV unit is one stop, and that compensation shifts the time in A mode, the aperture in S mode, and ISO in manual with Auto ISO. In the previous two lessons, you learned why the meter goes wrong, and in which direction compensation should go depending on whether the measured area is light or dark.

This lesson brings those pieces together and turns compensation into a working habit. Compensation may look like a tool for fixing mistakes, but it is really a tool for communication: you know the scene's tone, the camera doesn't. Compensation is the way of telling the camera what you know. From this angle, you will see that good photographers use compensation not less but more often, because in every new scene they leave the camera a short note.

Simple explanation

How do you read and set compensation?

Compensation shifts the exposure the camera suggests in the plus or minus direction. On many cameras it runs from minus three to plus three stops; on some cameras it stretches as far as minus five to plus five. These limits are the compensation range. Each click of the dial is usually a third of a stop. On phones, compensation is usually made by tapping the screen and sliding a finger up or down, and it is shown with a sun icon; the steps may be finer and the limits narrower.

The sneakiest feature of compensation is that it is persistent. On many cameras, compensation stays in place even after you switch the camera off and on. The plus two you set in the snow can make the photos you take in a café the next day pure white. That is why it is a good habit to glance once at the compensation indicator in the viewfinder or on the screen when you start every shoot. On phones, on the other hand, compensation is usually reset when you go back to the lock screen or the app closes; this, the other way round, means setting it again every time.

Compensation or manual?

Compensation and manual mode do the same job by different paths: both let you choose a brightness different from the camera's suggestion. The difference between them is what happens when the light changes. With compensation, the camera measures the scene again in every frame and applies the correction you added to this new reading. When the light changes, the exposure follows it; you only keep the amount of the correction. In manual mode, on the other hand, the settings are fixed; if the light changes, the photo changes too.

The choice of compensation versus manual rests on a single question: is the light changing, or the background? If the light is constant but the backgrounds entering the frame are changing, for example a person moving in steady window light, a fixed manual setting keeps the face in place. If the light is changing but the scene's tone stays the same, for example on a snowy hill with clouds passing over, compensation is more practical: plus two for the snow, and the camera handles the rest along with the clouds. If both are changing, tying manual mode to Auto ISO and keeping compensation on as well is often the most flexible solution.

How does the metering mode affect compensation?

When the metering mode changes, the amount of correction needed changes too. Matrix metering may notice a wide bright sky or snow and try to correct part of it on its own; that is why in snow, plus one is sometimes enough with matrix metering, while plus two may be needed when you look at the snow with spot metering. Center-weighted metering stands somewhere between the two. Spot metering, on the other hand, makes no correction at all and pulls the point you measure exactly to middle gray; that is why the compensation needed depends only on the tone of that point.

The practical lesson from this is: make a habit of working with a single metering mode and learn its behavior. If you keep changing modes, you have to adapt to a different compensation logic every time. Many photographers work with matrix metering in everyday shooting and set compensation for the scene as a whole; in difficult light they switch to spot metering and give compensation for the tone of the point they measure. Two modes are two separate ways of thinking; not mixing them reduces mistakes.

How does compensation keep a face steady?

The most valuable use of compensation in portraits is keeping a face's tone steady when photographing the same person in front of changing backgrounds. When you work with matrix metering, the camera looks at the whole scene in every frame; when the person comes in front of a light-colored wall it darkens the face, and when they step into a dark corridor it brightens it. Changing the compensation according to the background, that is shifting toward plus at a white wall and toward minus in a dark corridor, meets this swing and keeps the face in the same tone. This is background-based compensation: what decides the compensation here isn't the skin itself but how light or dark the background is.

With spot metering, on the other hand, the situation turns around: the background drops out of the calculation, and what decides the compensation is the skin's tone. A little minus on a face darker than a mid tone, a little plus on a face lighter than a mid tone. On mirrorless cameras and phones, the screen or electronic viewfinder usually shows the result of compensation before you shoot; this exposure preview makes it easier to bring the face to the right tone. Cameras with an optical viewfinder have no such preview; there you need to take the first frame and zoom in on the face on the screen. In both cases, the last word is whether the skin's color and the detail of its texture have stayed in place.

Visual evidence

In a museum, you are photographing a dark-skinned young woman walking between rooms, in A mode with matrix metering. First she stops in front of a painting in a white-walled gallery. Compensation is at zero; the camera has taken the white wall for too much light and darkened her face. You set compensation to plus one; her face brightens, and her brown skin and the fine light on her cheek can be made out.

Then she steps into a dim corridor paneled in dark wood. You have forgotten compensation at plus one: her face is too bright, and her skin has slid into a pale gray. You set compensation to minus two-thirds, and her face returns to its tone in the gallery. Finally she steps out into the sunny inner courtyard; the mid-toned stone floor and the shaded walls balance the scene. You turn compensation back to zero. Three places, three compensation values; but in all three frames, the same face, in the same tone.

Common mistakes

Summary

Exposure compensation is the fastest way to tell the camera a scene tone it doesn't know: on most cameras it works between minus three and plus three stops, in steps of a third, and because it is persistent it should be checked before every shoot. If the light is changing but the scene's tone is constant, compensation is more consistent; if the light is constant but the backgrounds are changing, manual mode is; the same scene asks for different amounts of compensation with matrix and spot metering. Changing compensation according to the background with matrix metering, giving it according to the skin's tone with spot metering, and checking the face with a live preview or by zooming in on the first frame keeps a face of any tone in the same tone across changing backgrounds.

Mini assignment

In this assignment you will turn compensation into a habit.

1. Find your camera's compensation range and how many stops one click is, change the compensation, switch the camera off and on, and see whether the value stays in place.
2. Photograph a friend in A mode with matrix metering, first in front of a light wall, then in front of a dark background, then in front of a mid-toned surface, and note the compensation value that brings the face to the same tone in front of each background.
3. In front of the same three backgrounds, switch to spot metering, put the spot on the cheek, and this time see how the compensation needed is affected not by the background but by the skin.
4. In a place where the light is constant, do the same shoot in manual mode and compare it with the frames you took with compensation.

Check yourself

• Do you know whether compensation is persistent on your camera?
• Did you see in your own frames that compensation depends on the background with matrix metering and on the skin with spot metering?
• In front of all three backgrounds, is your friend's face in the same tone and in its own color?

Glossary

Mini quiz

1. On many cameras, what happens to the compensation value when the camera is switched off and on?

• A) It resets by itself
• B) It stays in place; that is why it should be checked before every shoot
• C) It doubles
• D) It is transferred to ISO

2. On a snowy hill with clouds passing over, which approach is more practical?

• A) Compensation; the correction given for the snow is kept while the camera follows the changing light
• B) Manual mode with fixed settings
• C) Full auto and zero compensation
• D) Shooting with spot metering and zero compensation

3. Why do matrix and spot metering ask for different amounts of compensation in the same snowy scene?

• A) Because spot metering recognizes snow better
• B) Because matrix metering doesn't measure at all
• C) Matrix metering can correct part of the brightness on its own, while spot metering pulls the point it measures straight to middle gray
• D) There is no difference between them

4. When a person photographed with matrix metering moves from in front of a white wall into a dark corridor, how should compensation change to keep the face steady?

• A) Toward minus at the wall, toward plus in the corridor
• B) It should stay at zero in both
• C) It should stay at plus two in both
• D) Toward plus at the wall, toward minus in the corridor

Answers

1. B — Many cameras store compensation as a setting; because the value given in the previous scene can spoil the new scene, you need to look at the indicator.
2. A — With compensation, the camera measures the scene again in every frame and follows the changing light; the plus correction added for the snow is kept in every frame.
3. C — Matrix partly takes bright areas such as sky or snow into account; spot pulls the point to middle gray without any correction.
4. D — With matrix metering, the camera takes the white wall for too much light and the dark corridor for too little; changing compensation according to the background keeps the face's tone steady.

Summary card

• Compensation tells the camera the scene's tone; usually ±3 stops, in steps of a third.
• Compensation is persistent: look at the indicator before every shoot.
• If the light is changing, compensation; if the light is constant, manual.
• Matrix corrects part of the scene on its own, spot doesn't correct at all; get used to one mode.
• With matrix, give compensation for the background; with spot, for the skin; check the face in the preview or by zooming in.

Bridge to the next lesson

With compensation you tell the camera the scene's tone and check the result on the screen with your eye. But the eye is easily fooled when looking at a small screen in bright sun. Did you know the camera also offers you a graph: that mountain-shaped drawing shows how dark and how bright the photo is, independently of the eye. The next lesson teaches you to read this graph, the histogram.