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The shutter controls not only exposure, but also the
ability to stop motion. Fast shutter speeds are used
in sport photography 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 recommended with slow shutter
speeds.
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.
WHAT IS AN EV? WHAT IS A STOP?
Ev stands for exposure value. Stop refers to click stops in mechanical cameras. A change of one Ev
or one stop will adjust the exposure calculated by the camera by a factor of two – +1.0 Ev is twice as
much light, -1.0 Ev is one half as much light, +2.0 Ev is four times as much light, and -2.0 Ev is one
quarter as much light.
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