A telephoto lens is a camera lens with a narrow angle of view and a longer focal length than a lens for the normal image size produced by that camera.
Function
A telephoto lens zooms in on distant objects, making it a frequent choice of news photographers and sports photographers--or parents homing in on their child in a parade or graduation ceremony. This type of lens also can be flattering for candid wedding photography or for portraits.
Features
The key feature of a telephoto lens is a long focal length, or the measure of how strongly it focuses light. This gives an image a shallow depth of field, meaning unwanted objects in the foreground and background can be blurred easily to concentrate on the subject.
Types
Depending on size, lenses are classified as moderate telephoto, medium telephoto and super-telephoto lenses.
Size
For the 35 mm format, moderate-length telephoto lenses can be anything greater than 35 mm, typically 85 mm to 130 mm. Many portrait photographers opt for 105 mm. Medium telephoto lenses range from about 135 mm to 300 mm. A super-telephoto lens is about 400 mm to 800 mm.
Considerations
As the lens size increases, so does the expense--and the weight. Telephoto lenses can go out of focus easily because of their narrow view, so use a tripod for accuracy and support.
Tags: focal length, telephoto lens, telephoto lenses
