telephoto lens

(redirected from Long lens)
Also found in: Dictionary, Thesaurus.

telephoto lens

a compound camera lens in which the focal length is greater than that of a simple lens of the same dimensions and thus produces a magnified image of a distant object

Telephoto Lens


a photographic lens with a focal length that is longer than normal, in which the distance between the front surface of the first lens and the back focal plane is shorter than in other types of long-focus lenses. This feature permits a reduction in the overall size of still and motion-picture cameras. Telephoto lenses are used in producing large-scale photographs of distant objects and for portraits.

Figure 1. Diagram of a two-element telephoto lens: (H′) back principal plane, (F′) back focal plane, (D1) converging element, (D2) diverging element, (L) distance from the front surface of the lens to the back focal plane, (f′) back focal distance

The most common designs for telephoto lenses make use of two components (Figure 1), each consisting of a group of lenses; the first group is a converging system, and the second is a diverging system. The components are combined in such a way that the back principal plane H’ is moved forward of the lens and the distance L is shortened. The shortening index Kt = L/f′ In some telephoto lenses, the focusing distance of the second group of lenses is positive, and Kt is close to unity. Such lenses are considered three-group systems.


telephoto lens

[¦tel·ə¦fōd·ō ′lenz]
A lens for photographing distant objects; it is designed in a compact manner so that the distance from the front of the lens to the film plane is less than the focal length of the lens.
References in periodicals archive ?
As I was the only photographer using a long lens, my 400mm became a sort of spotting scope.
Bring a telephoto lens and film of ISO (ASA) 100 or higher: slower film may not allow the faster shutter speeds required by a long lens, cloudy weather, and boat motion.
It is essential when engaging the camera's retractable 12x optical zoom lens because the extension of a long lens magnifies camera shake in direct proportion with the amount of lens magnification employed.
Photographing birds in flight involves handholding the camera with a long lens and keeping the bird within the frame as it flies across or towards you.
The photos were captured with a long lens while the royal couple were relaxing by a swimming pool at the Chateau d'Autet, a secluded 19th century hunting lodge in Provence owned by the Queen's nephew Lord Linley.
Instead of a long lens, we'll get you in the sights of something a bit more powerful," the Mirror quoted one as warning the editor of Closer magazine.
The long lens photographer has done the Duchess the biggest favour ever - that of saving her life, as this could have been an assassin with a telephoto lens.
But there's a world of difference between a carefully posed picture of a glamour model, or the knowing pose of a publicity-seeking celebrity, and a furtive photo taken with a long lens.
5, which was showcased at NAB, is designed for use within OB vans, at stadiums, sporting events, arenas, larger venues -- anywhere a long lens would be beneficial in capturing detail and close up images from far distances.
Ianmoran1970 had gone the other direction, with a long lens shot of the Iron Men at Crosby that steps away from the frequent images of them looking out to sea.
The glitzy glamorous frocks, the flashing glare of long lens paparazzi and the deafening screams from adoring crowds.