depth of field


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depth of field

For a given setting of an optical system (or a steady state of accommodation of the eye) it is the distance over which an object may be moved without causing a sharpness reduction beyond a certain tolerable amount. Depth of field increases when the diaphragm (or pupil) diameter diminishes as, for example, in old eyes (Fig. D1). Examples: viewing at infinity, the depth of field ranges between infinity and about 3.6 m for a pupil of 4 mm in diameter; and between infinity and about 2.3 m for a 2 mm pupil. At a viewing distance of 1 m, the depth of field ranges from about 1.4 m to 80 cm with a 4 mm pupil; and from about 1.8 m to 70 cm with a 2 mm pupil. See hyperfocal distance.
Fig. D1 Schematic representation of the depth of field and the depth of focus of an eye fixating an object at O (I, retinal image size corresponding to the tolerable resolution)enlarge picture
Fig. D1 Schematic representation of the depth of field and the depth of focus of an eye fixating an object at O (I, retinal image size corresponding to the tolerable resolution)
References in periodicals archive ?
"Nobody is going to throw away their night vision goggles because of the poor depth of field, but the full promise of night vision isn't realized until this problem is overcome," James said.
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As an example of determining depth of field, first find the hyperfocal distance H for the 75-mm lens
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Looking through a small pinhole increases the eye's depth of field and sharpens the vision.
The actual range of distance in which the picture is sufficiently in focus to be useful is called depth of field. Depth of field increases as available light increases.
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For high-magnification work, a more shallow etch depth is desired due to the more limited depth of field of the light microscope, while for low-magnification examination a deeper contrast etch is best.