Depth of Field
DEFINITION:
A zone extending in front of and behind the focused distance where the blur is too insignificant to be noticeable and for practical purposes can be accepted as a sharp photographic image.
The certain range of latitude in front of and behind the focused image within which objects can be photographed sharply (permissible circle of confusion) is called "depth or focus".
DESCRIPTION:
The depth of field is obtained by calculating the range of depth within which a focused object can be perceived as sharp, where the center of a lens has no aberration and by assuming the diameter of a permissible circle of confusion (in most cases 1/30mm for 35mm camera, or 1/20mm for 6 x 6 cm cameras is used).
Depth of field:
- Becomes shallower when a longer focal length is used, and increases when a shorter focal length is used.
- Becomes shallower when the subject distance decreases, and increases when the subject distance is increased.
- Becomes shallower when the acceptable circle of confusion is used. The acceptable circle of confusion depends upon the size of the sensor in the camera used.
Zone focusing, focus mark setting and fixed focus utilize the depth of field of the lens.
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