Telephoto

Telephoto refers to a category of camera lenses designed to produce a narrow field of view and increased magnification relative to standard lenses. The term describes optical designs that achieve a long focal length while keeping the external length of the lens shorter than the focal length, using a telephoto group that reduces the overall barrel length. In practice, telephoto lenses are typically long focal lengths starting around 70–135 mm on full-frame cameras, with many common models in the 200 mm and longer range, including zooms such as 70–200 mm or 100–400 mm. Prime telephotos have a single focal length, while zoom telephotos cover a range.

Compared with standard or wide-angle lenses, telephotos magnify distant subjects and narrow perspective exaggeration, producing shallower depth of field and stronger subject isolation at similar framing. They provide a narrow angle of view, making accurate composition feasible from a distance. The design often results in greater weight and length, though many modern telephotos use internal focusing and image stabilization to compensate for camera shake. Some models accept teleconverters to extend reach.

Common applications include portrait photography, wildlife and sports, aviation, and cinematography, where distance to the subject or selective framing is important. Telephotos are also used in surveillance and investigative contexts, though professional use in such fields is governed by ethical and legal considerations.

Historically, the term telephoto derives from the idea of a long focal length implemented in a shorter barrel; early designs used negative elements to shorten the optical path. Today, telephoto lenses range from compact primes for travel to large professional zooms with fast maximum apertures.