12 APERTURE
The smaller the aperture, the wider the range of sharpness. This is illustrated by the picture above which was taken at f/22. Compare it with the photo to s right. This extended depth of field is especially good for such subjects as landscapes.
The larger the aperture, the narrower the range of sharpness. An aperture of f/1.4, for instance, can isolate your subject from its surroundings. This is often used to blur a disturbing background in portraiture.
Depth of field is also greater the shorter the focal length of the lens. A 24mm lens, for example, will show greater depth of field than a 50mm lens, provided the aper- ture and shooting distance are the same. Depth of field is also greater the longer the shooting distance, and is generally greater in the background than in the foreground by a ratio of two to one.
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