800mm

In photography, the term 800mm is usually used to refer to lenses with focal length of 800 mm. These lenses are commonly used in low-level refractor telescopes. A refractor telescope is a dioptric telescope which makes use of a lens as its objective to form an image. The "refractive telescope" design, though originally intended for usage in spy glasses and astronomical telescopes, is presently also used in other devices like binoculars and long or telephoto camera lenses.

The term 800mm is also used to refer to telephoto lenses with a focal length of 800 mm. An 800mm telephoto lens, just like other telephoto lenses, has its optical centre outside of its physical construction, and the entire lens assembly is between the optical centre and the focal plane. Telephoto lenses are best known for making distant objects appear closer and magnified, and as such are widely used in situations where getting close to the subject is either not desirable or possible, for example wildlife photography, nature photography, etc.

Old and new 800mm lenses, 800mm refractive telescopes, 800mm telephoto lenses, 800mm Nikor lenses, 800mm Nikon lenses, 800mm Sigma lenses, and other such photography products can be found on sale on many online shopping portals.