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.
WHAT IS A STOP? WHAT IS AN EV?
The term “stop” comes from the name of aperture plates in old lenses. Ev stands for exposure value. A change of one stop or one Ev adjusts the exposure by a factor of two.
+3 stops | +3.0 Ev | 8X as much light |
+2 stops | +2.0 Ev | 4X as much light |
+1 stop | +1.0 Ev | 2X as much light |
| Calculated exposure |
|
1/2 as much light | ||
1/4 as much light | ||
1/8 as much light |
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