The lens aperture controls not only exposure, but also depth of field; the area between
the closest object in focus and the furthest object in focus. The larger the aperture
value, the greater the depth of field and the longer the shutter speed needed to make
the exposure. The smaller the aperture value, the shallower the depth of field and the
faster the shutter speed needed to make the exposure. Usually landscape photographs
use a large depth of field (large
aperture value) to keep the fore-
ground and background in focus,
and portraits use a shallow depth
of field (small aperture value) to
separate the subject from the
background.
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A SHORT GUIDE TO PHOTOGRAPHY
The shutter controls not only exposure,
but also the ability to stop motion. Fast
shutter speeds are used in sport pho-
tography to stop action. Slow shutter
speeds can be used to show the flow of
motion such as water cascading over a
waterfall. The use of a tripod is recom-
mended with slow shutter speeds.
Photography can be a rewarding pursuit. It is a broad and disciplined field that can take
years to master. But the pleasure in making photographs and the joy of capturing a
magical moment cannot be compared. The guide is an introduction to some basic pho-
tographic principles.
The change in aperture and shutter speed is not apparent in the live image. Unlike film
cameras, test photographs can be taken and immediately viewed. For critical work,
take a test photograph at the set aperture or shutter speed and view the result in quick
view (p.34). The image can be deleted if not acceptable and another test image can be
taken at a different setting.
Depth of field also changes with focal
length. The smaller the focal length,
the greater the depth of field; the
longer the focal length, the shallower
the depth of field.