In
photographic optics
Optics is the branch of physics that studies the behaviour and properties of light, including its interactions with matter and the construction of optical instruments, instruments that use or Photodetector, detect it. Optics usually describes t ...
, the Zeiss formula is a supposed formula for computing a
circle of confusion (CoC) criterion for
depth of field
The depth of field (DOF) is the distance between the nearest and the farthest objects that are in acceptably sharp focus (optics), focus in an image captured with a camera. See also the closely related depth of focus.
Factors affecting depth ...
(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 biblical or related writings not forming part of the accepted canon of scripture, some of which might be of doubtful authorship or authenticity. In Christianity, the word ''apocryphal'' (ἀπόκρυφος) was first applied to ...
, 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, 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 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
*
Depth of field
The depth of field (DOF) is the distance between the nearest and the farthest objects that are in acceptably sharp focus (optics), focus in an image captured with a camera. See also the closely related depth of focus.
Factors affecting depth ...
*
Hyperfocal distance
References
{{reflist
Science of photography