Circle of confusion
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In optics, a circle of confusion is an optical spot caused by a cone of light rays from a lens not coming to a perfect focus when imaging a point source. It is also known as disk of confusion, circle
An early calculation of CoC diameter ("indistinctness") by "T.H." in 1866.
Hyperfocal distance
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In optics and photography, hyperfocal distance is a distance from a lens beyond which all objects can be brought into an "acceptable" focus. As the hyperfocal distance is the focus distance giving the
Circle of confusion
…f = f 2 N ( S 1 − f ) . If the c value is fixed as a circle of confusion diameter limit, either of these can be solved for subject distance to get the hyperfocal distance, with approximately equivalent results. Before it was applied to photography, the concept of circle of confusion was applied to optical instruments…
Minox LX camera with hyperfocal red dot
Nikon 28mm f/2.8 lens with markings for the depth of field. The lens is set at the hyperfocal distance for f/22. The orange mark corresponding to f/22 is at the infinity mark (∞). Focus is acceptable from under 0.7 m to infinity.
Minolta 100–300 mm zoom lens. The depth of field, and thus hyperfocal distance, changes with the focal length as well as the f-stop. This lens is set to the hyperfocal distance for f/32 at a focal length of 100 mm.