Long-focus lens in the context of Wide-angle lens

A refracting telescope (also called a refractor) is a type of optical telescope that uses a lens as its objective to form an image (also referred to a dioptric telescope). The refracting telescope design was originally used in spyglasses and astronomical telescopes but is also used for long-focus camera lenses. Although large refracting telescopes were very popular in the second half of the 19th century, for most research purposes, the refracting telescope has been superseded by the reflecting telescope, which allows larger apertures. A refractor's magnification is calculated by dividing the focal length of the objective lens by that of the eyepiece.

Refracting telescopes typically have a lens at the front, then a long tube, then an eyepiece or instrumentation at the rear, where the telescope view comes to focus. Originally, telescopes had an objective of one element, but a century later, two and even three element lenses were made.

A telephoto lens, also known as telelens, is a specific type of a long-focus lens used in photography and cinematography, 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 group that extends the light path to create a long-focus lens in a much shorter overall design. The angle of view and other effects of long-focus lenses are the same for telephoto lenses of the same specified focal length. Long-focal-length lenses are often informally referred to as telephoto lenses, although this is technically incorrect: a telephoto lens specifically incorporates the telephoto group.

In filmmaking, a long take (also called a continuous take, continuous shot, or oner) is shot with a duration much longer than the conventional editing pace either of the film itself or of films in general. Significant camera movement and elaborate blocking are often elements in long takes, but not necessarily so. The term "long take" should not be confused with the term "long shot", which refers to the use of a long-focus lens and not to the duration of the take. The length of a long take was originally limited to how much film the magazine of a motion picture camera could hold, but the advent of digital video has considerably lengthened the maximum potential length of a take.