Metrogon is a high resolution, low-distortion, extra-wide field (90 degree
field of view
The field of view (FoV) is the extent of the observable world that is seen at any given moment. In the case of optical instruments or sensors it is a solid angle through which a detector is sensitive to electromagnetic radiation.
Humans a ...
)
photographic lens
A camera lens (also known as photographic lens or photographic objective) is an optical lens or assembly of lenses used in conjunction with a camera body and mechanism to make images of objects either on photographic film or on other media capab ...
design, popularized by
Bausch and Lomb
Bausch + Lomb is an eye health products company based in Vaughan, Ontario, Canada. It is one of the world's largest suppliers of contact lenses, lens care products, pharmaceuticals, intraocular lenses, and other eye surgery products. The compan ...
. Variations of this design are said to have been used extensively by the
US military
The United States Armed Forces are the Military, military forces of the United States. The armed forces consists of six Military branch, service branches: the United States Army, Army, United States Marine Corps, Marine Corps, United States N ...
for use in
aerial photography
Aerial photography (or airborne imagery) is the taking of photographs from an aircraft or other airborne platforms. When taking motion pictures, it is also known as aerial videography.
Platforms for aerial photography include fixed-wing aircra ...
on the T-11 camera.
The most common Metrogon lenses have a
f number
In optics, the f-number of an optical system such as a camera lens is the ratio of the system's focal length to the diameter of the entrance pupil ("clear aperture").Smith, Warren ''Modern Optical Engineering'', 4th Ed., 2007 McGraw-Hill ...
of 6.3 and a
focal length
The focal length of an optical system is a measure of how strongly the system converges or diverges light; it is the inverse of the system's optical power. A positive focal length indicates that a system converges light, while a negative foca ...
of 6 inches. The company name Bausch and Lomb and the US
Patent
A patent is a type of intellectual property that gives its owner the legal right to exclude others from making, using, or selling an invention for a limited period of time in exchange for publishing an enabling disclosure of the invention."A p ...
number 2031792 are prominently inscribed on the front of the lens barrel. However, the said US Patent is of a 4 element lens that belongs to one inventor named Robert Richter of
Carl Zeiss AG
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 f ...
, filed in 1934. For this reason, it is said that the Metrogon is a US version of the popular and very similar (if not identical)
Topogon
Topogon is a wide field (originally 100 degrees field of view), symmetrical photographic lens designed by Robert Richter in 1933 for Zeiss Carl FA. Lenses produced under the name Metrogon also cite the US patent of the Topogon design. The initial ...
design by Carl Zeiss.
In 1943, Bausch and Lomb themselves filed a patent for a similar, f/6.3 lens design but with 5 elements, under the US patent number 2325275, showing less distortion than the lens in the Carl Zeiss patent. It is not certain whether Bausch and Lomb incorporated their own design instead of the Zeiss design when producing lenses under the Metrogon name later on. The Bausch and Lomb patent also compares the distortion of their design favorably to another 5 element lens (US patent number 2116264) which has a slightly wider maximum f-number of f/5.6.
References
{{reflist
External links
The Metrogon Page
Photographic lenses