9 EXPOSURE
9Exposure
The amount of light that exposes a frame is determined by the aperture and shutter speed. The size of the aperture controls the amount of light allowed to reach the film, while the shutter speed controls how long the light strikes the film. For the same exposure, a change in shutter speed requires an equal and opposite change in aperture, and vice versa. There are usually several combinations of shutter speed and aperture which will give the same exposure. If. for example, the meter indicates that exposure will be correct at f/4 and 1/60 sec., you usually have other combinations to choose from. Some of the combinations in this example include f/5.6 at 1/30 sec. and f/2.8 at 1/125 sec. The two main considerations involved in selecting one particular combination over the others are the subject’s motion and depth of field; each of these affects the way a picture will look. You can control the effect of a picture simply by choosing a certain shutter speed and aperture combination. The next three sections provide information which you may find useful whether you are using the camera manually or automatically with an AE accessory.
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