The Canon EF 400mm are seven super-telephoto lenses made by

Canon Canon or Canons may refer to: Arts and entertainment * Canon (fiction), the material accepted as officially written by an author or an ascribed author * Literary canon, an accepted body of works considered as high culture ** Western canon, th ...

. These lenses have an EF mount that work with the

EOS In ancient Greek mythology and Ancient Greek religion, religion, Eos (; Ionic Greek, Ionic and Homeric Greek ''Ēṓs'', Attic Greek, Attic ''Héōs'', "dawn", or ; Aeolic Greek, Aeolic ''Aúōs'', Doric Greek, Doric ''Āṓs'') is the go ...

line of cameras. These lenses are widely used by

sports Sport is a physical activity or game, often competitive and organized, that maintains or improves physical ability and skills. Sport may provide enjoyment to participants and entertainment to spectators. The number of participants in ...

and wildlife photographers. Canon has manufactured 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 ...

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 photographic lens, lenses made by Canon Inc., Canon. These lenses are used between any compatible Canon EF lens mount, EF type lens and any of the Canon Canon EOS, EOS line of cameras. Whe ...

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 extragalact ...

. 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 Luminosity, luminous host galaxy (also known as the primary galaxy). Satellite galaxies and their constituents ...

. 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