The Textbook of Digital Photography - PhotoCourse

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how to oVerride AutomAtiC exPoSure

Most digital cameras provide ways to override the automatic exposure system

to get the exposure you want. The most common choices are exposure com-

pensation, exposure lock, and autoexposure bracketing.

Exposure Compensation

You can’t make an image lighter or darker by changing the shutter speed or

aperture in any mode but manual. This is because when you change one of

the settings, the other changes automatically to keep the exposure constant.

Exposure compensation is the feature you use to capture an image that’s

lighter or darker than one the camera would produce automatically. To light-

en a picture, you increase the exposure; to darken it, you decrease the expo-

sure. The amount you increase or decrease the exposure is specified in stops.

If you select a + value, the image will be brighter. If you select a – value it

will be darker. It’s easy to use exposure compensation because most cameras

display a scale to guide you and you can preview the effects of your changes

on the monitor, if the camera lets you use it to compose images. You can also

check an image in review or playback mode and even examine its histogram

on many cameras.

how to override AutomAtiC exposure

When you adjust exposure compensation you can do so in full stops and even

finer increments—usually one-third or one-half stops. On most cameras you will

see a scale displayed when you use this command. The “0” indicates the exposure

suggested by the camera. As you adjust the exposure toward the plus (+) side of

the scale the image gets lighter. As you adjust it toward the minus (-) side it gets

darker. Here you see the results as it’s adjusted from +2 (left) to -2 (right). The

effect of the changes on the image are dramatic.

The universally
recognized icon for
exposure compensation.

Many digital cameras
display an exposure
scale when you use
exposure compensation.

Click to explore
exposure compensation.

TiP

many digital cameras

let you select 1/3

or 1/2 stop incre-

ments for exposure

settings. Setting it

to 1/3rd stops gives

you finer control over

the exposure.

The histogram on the
right shows that the
image is overexposed
and pixels at the
far right end (the
highlights) are being
clipped. Using exposure
compensation at the
time the photo was
taken shifted the
histogram to the left
(bottom left). With this
adjustment no details
are lost in the shadows
or highlights.