The term fisheye was coined in 1906 by American physicist and inventor Robert W. Wood based on how a fish would see an ultrawide hemispherical view from beneath the water (a phenomenon known as Snell's window).

For digital cameras using smaller imagers such as 1/4 in and 1/3 in format CCD or CMOS sensors, the focal length of "miniature" fisheye lenses can be as short as 1–2 mm.

They are also used for scientific photography, such as recordings of aurora and meteors, and to study plant canopy geometry, and to calculate near-ground solar radiation.

In 1779, Horace Bénédict de Saussure published his downward-facing fisheye view of the Alps: "All the objects are drawn in perspective from the centre".

The experiment was Wood's attempt "to ascertain how the external world appears to the fish" and hence the title of the paper was "Fish-Eye Views, and Vision under Water".

[1] Wood subsequently built an improved "horizontal" version of the camera omitting the lens, instead using a pinhole pierced in the side of a tank, which was filled with water and a photographic plate.

[1] In his conclusion, Wood thought that "the device will photograph the entire sky [so] a sunshine recorder could be made on this principle, which would require no adjustment for latitude or month" but also wryly noted "the views used for the illustration of this paper savour somewhat of the 'freak' pictures of the magazines.

Bond described an improvement to Wood's apparatus in 1922 which replaced the tank of water with a simple hemispheric glass lens, making the camera significantly more portable.

The focal length depended on the refractive index and radius of the hemispherical lens, and the maximum aperture was approximately f/50; it was not corrected for chromatic aberration and projected a curved field onto a flat plate.

[5]: 146  Hill also described three different mapping functions of a lens designed to capture an entire hemisphere (stereographic, equidistant, and orthographic).

[3][12] Distortion is unavoidable in a lens that encompasses an angle of view exceeding 125°, but Hill and Beck claimed in the patent that stereographic or equidistant projection were the preferred mapping functions.

[5]: 148 [16] Compared to the 1923 Hill Sky Lens, the 1932 Weitwinkelobjektiv featured two diverging meniscus elements ahead of the stop and used a cemented achromatic group in the converging section.

[18] The AEG Weitwinkelobjektiv formed the basis of the later Nippon Kogaku (Nikon) Fisheye-Nikkor 16 mm f/8 lens of 1938, which was used for military and scientific (cloud cover) purposes.

[17][19] Nikon, which had a contract to supply optics to the Imperial Japanese Navy, possibly gained access to the AEG design under the Pact of Steel.

[19] Also in 1938, Robert Richter of Carl Zeiss AG patented the 6-element, 5-group Pleon lens,[20] which was used for aerial surveillance during World War II.

Testing on a captured lens after the war showed the Pleon provided an equidistant projection to cover a field of approximately 130°, and negatives were printed using a special rectifying enlarger to eliminate distortion.

[24] Several prototype examples of Sphaerogon lenses were recovered as part of the Zeiss Lens Collection seized by the Army Signal Corps as war reparations in 1945;[25] the collection, which the Zeiss firm had retained as a record of their designs, was later documented by Merté, the former head of optical computation for CZJ, working under Signal Corps officer Edward Kaprelian.

[36] The Fisheye-Nikkor 8 mm f/8 has a field of view of 180° and uses 9 elements in 5 groups; it has a fixed focus and built-in filters intended for black-and-white photography.

For example, British fashion photographer Tim Walker used a fisheye lens to capture the cover of Harry Styles' 2019 pop/rock album, Fine Line.

The focal length is determined by the angular coverage, the specific mapping function used, and the required dimensions of the final image.

[49] Sunex also makes a 5.6 mm fisheye lens that captures a circular 185° field of view on a 1.5x Nikon and 1.6x Canon DSLR cameras.

[52] More recently, the Japanese manufacturer Entaniya offers several fisheye lenses with angles of view up to 250° on 35 mm full frame, and up to 280° on smaller sensors (see list below).

As a result, on any non-square film format, the circular image will be cropped at the top and bottom, but still show black edges on the left and right.

Although this entails some loss of detail at the edges of the frame, the technique can produce an image with a field of view greater than that of a conventional rectilinear lens.