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 of indistinctness, blur circle, or blur spot.
In photography, the circle of confusion (“CoC”) is used to determine the depth of field, the part of an image that is acceptably sharp. A standard value of CoC is often associated with each image format, but the most appropriate value depends on visual acuity, viewing conditions, and the amount of enlargement. Properly, this is the maximum permissible circle of confusion, the circle of confusion diameter limit, or the circle of confusion criterion, but is often informally called simply the circle of confusion.
Real lenses do not focus all rays perfectly, so that even at best focus, a point is imaged as a spot rather than a point. The smallest such spot that a lens can produce is often referred to as the circle of least confusion.
Read more about Circle Of Confusion: Two Uses, Circle of Confusion Diameter Limit in Photography
Famous quotes containing the words circle of, circle and/or confusion:
“Writing about an idea frees me of it. Thinking about it is a circle of repetitions.”
—Mason Cooley (b. 1927)
“Writing about an idea frees me of it. Thinking about it is a circle of repetitions.”
—Mason Cooley (b. 1927)
“A woman’s beauty is a storm-tossed banner;
Under it wisdom stands, and I alone
Of all Arabia’s lovers I alone
Nor dazzled by the embroidery, nor lost
In the confusion of its night-dark folds,
Can hear the armed man speak.”
—William Butler Yeats (1865–1939)