In
photographic
Photography is the art, application, and practice of creating durable images by recording light, either electronically by means of an image sensor, or chemically by means of a light-sensitive material such as photographic film. It is employed i ...
optics
Optics is the branch of physics that studies the behaviour and properties of light, including its interactions with matter and the construction of instruments that use or detect it. Optics usually describes the behaviour of visible, ultraviole ...
, the Zeiss formula is a supposed formula for computing a
circle of confusion
In optics, a circle of confusion (CoC) 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 bl ...
(CoC) criterion for
depth of field
The depth of field (DOF) is the distance between the nearest and the furthest objects that are in acceptably sharp focus in an image captured with a camera.
Factors affecting depth of field
For cameras that can only focus on one object dist ...
(DoF) calculations. The formula is
, where
is the diagonal measure of a camera format, film, sensor, or print, and
the maximum acceptable diameter of the circle of confusion.
The Zeiss formula is
apocryphal
Apocrypha are works, usually written, of unknown authorship or of doubtful origin. The word ''apocryphal'' (ἀπόκρυφος) was first applied to writings which were kept secret because they were the vehicles of esoteric knowledge considered ...
, in the sense that it has grown to be a well-known named concept by propagation through the internet, even though it has no official origin, little connection to
Carl Zeiss Company, and no recognition or usage in the photographic industry outside the web community.
The number 1/1730 derives from a circle of confusion diameter of 0.025 mm on a full-frame 35 mm
film format
A film format is a technical definition of a set of standard characteristics regarding image capture on photographic film for still images or film stock for filmmaking. It can also apply to projected film, either slides or movies. The primary ...
, with diagonal size about 43.25 mm (43.25/0.025 is 1730). The CoC size of 0.025 mm for this format appears in Jacobson's Photographic Lenses Tutorial,
[
]
and the 1730 in his 1996 Photographic Lenses FAQ.
Jacobson derived the 0.025 mm CoC number from analysis of the Zeiss
Triotar
Carl Zeiss AG (), branded as ZEISS, is a German manufacturer of optical systems and optoelectronics, founded in Jena, Germany in 1846 by optician Carl Zeiss. Together with Ernst Abbe (joined 1866) and Otto Schott (joined 1884) he laid the ...
lens DoF markings on the
Rollei B35 (see photo). The manual for the Rollei B35 also states 0.025 mm CoC for its tabulated DoF distances, though it also includes an example DoF reading that implies a larger CoC.
By 2001, the term "Zeiss formula" had appeared, in the manual for the on-line DoF calculator f/calc.
On the other hand, Zeiss gives the values ''d''/1000 as the traditional standard and ''d''/1500 as the modern standard.
[
]
See also
*
Circle of confusion
In optics, a circle of confusion (CoC) 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 bl ...
*
Depth of field
The depth of field (DOF) is the distance between the nearest and the furthest objects that are in acceptably sharp focus in an image captured with a camera.
Factors affecting depth of field
For cameras that can only focus on one object dist ...
*
Hyperfocal distance
In optics and photography, hyperfocal distance is a distance beyond which all objects can be brought into an "acceptable" focus. As the hyperfocal distance is the focus distance giving the maximum depth of field, it is the most desirable distan ...
References
{{reflist
Science of photography