The Canon EF 400mm are seven

super-telephoto lenses A telephoto lens, in photography and cinematography, is a specific type of a long-focus lens in which the physical length of the lens is shorter than the focal length. This is achieved by incorporating a special lens group known as a ''telephoto ...

made by

Canon Canon or Canons may refer to: Arts and entertainment * Canon (fiction), the conceptual material accepted as official in a fictional universe by its fan base * Literary canon, an accepted body of works considered as high culture ** Western ca ...

. These lenses have an EF mount that work with the

EOS In ancient Greek mythology and religion, Eos (; Ionic and Homeric Greek ''Ēṓs'', Attic ''Héōs'', "dawn", or ; Aeolic ''Aúōs'', Doric ''Āṓs'') is the goddess and personification of the dawn, who rose each morning from her home at ...

line of cameras. These lenses are widely used by

sports Sport pertains to any form of competitive physical activity or game that aims to use, maintain, or improve physical ability and skills while providing enjoyment to participants and, in some cases, entertainment to spectators. Sports can, ...

and wildlife photographers. Canon currently manufactures four 400mm

prime lens In film and photography, a prime lens is a fixed focal length photographic lens (as opposed to a zoom lens), typically with a maximum aperture from f2.8 to f1.2. The term can also mean the primary lens in a combination lens system. Confusion be ...

es: *EF 400mm 2.8L IS III USM *EF 400mm 2.8L IS II USM *EF 400mm 4 DO IS II USM *EF 400mm 5.6L USM The 400mm 4 DO IS II USM, which replaced an earlier version of the same lens in 2014, is one of only two Canon lenses that make use of diffractive optics (the other is the EF 70–300mm f/4.5–5.6 DO IS USM). The use of diffractive optics allows the lens to be significantly lighter than it might otherwise be.the-digital-picture.com
/ref> These lenses are compatible with the

Canon Extender EF The Canon Extender EF lenses are a group of teleconverter lenses made by Canon. These lenses are used between any compatible EF type lens and any of the Canon EOS line of cameras. When used with a compatible lens, they will multiply the focal le ...

teleconverters.

Specifications of the EF 400mm lenses

Use in astronomy

Canon 400 mm f/2.8 L IS II USM lenses are used in the

Dragonfly Telephoto Array The Dragonfly Telephoto Array is a ground-based optical telescope array developed at the Dunlap Institute for Astronomy & Astrophysics of the University of Toronto in Canada. The array uses a combination of telephoto lenses to observe extragalacti ...

. The array is designed to image astronomical objects with low surface brightness such as some

satellite galaxies A satellite galaxy is a smaller companion galaxy that travels on bound orbits within the gravitational potential of a more massive and luminous host galaxy (also known as the primary galaxy). Satellite galaxies and their constituents are bound ...

. The array started with three lenses but this has since increased to 24 with plans for 50.

References

Canon EF lenses Canon L-Series lenses {{Photo-stub