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Chapter 2 Camera Handling, Care, and Support
Copyright Goodheart-Willcox Co., Inc.
Exposure Mode Selection
The most basic camera models do not provide
any shooting choices—shutter speed, aperture,
and ISO are all preset or automatically adjusted.
Most cameras, however, offer at least four ways
to operate the camera. See Figure 2-3. These
exposure modes are automatic, aperture priority,
shutter priority, and manual.
Often designated as AE, the automatic
exposure mode lets the camera make all
the decisions. The camera’s processor uses
readings from the built-in exposure meter to
select an aperture/shutter speed combination
that provides a properly exposed photograph.
On a film camera, the film speed (ISO) setting
is factored into the exposure decision. Digital
cameras also factor in the ISO setting, but
may alter the value to improve the exposure.
Auto exposure is the simplest mode to use
and gives acceptable results much of the time.
However, it cannot cope with certain kinds of
photographic situations, such as backlighted
subjects or rapid motion.
Some camera models have a Program AE
mode to allow limited control. In this mode, the
camera’s processor selects exposure settings
based on the meter reading, but you can
change either the shutter speed or aperture.
The processor will then make the appropriate
adjustment for a proper exposure.
In aperture priority mode, you select the
aperture setting, and the camera sets a shutter
speed based on its meter reading. The advantage
of using aperture priority is the ability to control
depth of field—the portion of the image, from
near to far, that is in acceptable focus. As aperture
size decreases, depth of field increases. At f/2,
a large aperture, depth of field is quite shallow.
At f/16, a small aperture, depth of field is much
greater. Aperture priority is often selected when
shooting landscapes. See Figure 2-4.
When a moving subject is involved,
shutter priority mode is typically selected. In
this mode, you select the shutter speed, and
the camera chooses an aperture based on its
meter reading. Slower shutter speeds, resulting
in longer exposures, capture motion blur.
Jack Klasey/Goodheart-Willcox Publisher
Figure 2-3. The exposure modes commonly found on
film and digital cameras.
Manual
Aperture priority Program AE
Automatic
Shutter priority
A B
Jack Klasey/Goodheart-Willcox Publisher
Figure 2-4. Depth of field increases as aperture decreases. A—In this scenic shot, depth of field is great, with
focus sharp from the nearest house to the distant mountains. Aperture was f/20 at 1/60 second using a 50 mm lens.
B—A 300 mm telephoto lens and an aperture of f/5.6 at 1/100 second result in very shallow depth of field. Focus is
sharp only for the central figure in this antique auto hood ornament.