What Is a Telephoto Lens?

A telephoto lens, also called a telephoto lens, refers to a photographic lens that has a longer focal length than a standard lens. Telephoto lenses are divided into two types: ordinary telephoto lenses and super telephoto lenses. The focal length of ordinary telephoto lenses is close to that of standard lenses, while the focal length of super telephoto lenses is much larger than that of standard lenses.

Telephoto lens

A telephoto lens, also called a telephoto lens, refers to a photographic lens that has a longer focal length than a standard lens. Telephoto lenses are divided into two types: ordinary telephoto lenses and super telephoto lenses. The focal length of ordinary telephoto lenses is close to that of standard lenses, while the focal length of super telephoto lenses is much larger than that of standard lenses.

Chinese name

Telephoto lens

Also known as

Telephoto lens

Explanation

A photographic lens with a longer focal length than a standard lens

Features

Small perspective, short depth of field, poor perspective effect, etc.

Taking interchangeable lenses suitable for 35mm SLR cameras as an example, a telephoto lens usually refers to

Shooting with a long focal length lens has the following characteristics:

The first is a small perspective. Therefore, the spatial scope of the scene is also small. At the same shooting distance, the captured image is larger than the standard lens, which is suitable for shooting details of distant scenes and shooting inaccessible subjects.

The second is the short depth of field. Therefore, a subject in a cluttered environment can be highlighted. However, it brings some difficulties to precise focusing. If the focusing is slightly inaccurate when shooting, it will cause the subject to be blurred.

Third, the perspective effect is poor. This lens has the characteristics of significantly compressing the depth of space and exaggerating the background.

When using a long focal length lens, it is generally used to shoot distant scenes. Due to the absorption of air and the effect of diffusely scattered light. Therefore, the contrast of the captured image is small, and the dust particles are more extinct. It is not easy to achieve very precise focus adjustment. Shooting with a super-telephoto lens with a diameter of more than 300mm makes it difficult to condense the light of each color at one point, which causes a problem of sub-spectrum. Based on the foregoing, the quality of the photographed work is sometimes not high.

Fourth, the longer the focal length of the lens, the more stable the camera must be to avoid image blur. As a rule of thumb, you can only shoot with the lens held in hand when the shutter speed is at least equal to the reciprocal of the focal length of the lens in millimeters, also known as a "safe shutter". That is to say, when the shutter speed is lower than 1/100 second, you cannot shoot with a 100mm lens, when it is lower than 1/500 second, you cannot shoot with a 500mm lens, and so on. For most telephoto shots, a tripod is required, so you not only have to carry that long lens, but also a tripod.

Although the use of long focal length lenses is affected by many factors, its advantages are major. Shoot landscape people, travel photography, and portrait photography at a long distance (when taking standard photos for ID cards, use a normal telephoto lens of about 100mm to reduce image distortion), and take photos of stage and sports games in the stands. Shooting animals in zoos, shooting beasts in the wild, taking auxiliary lenses for close-ups ... and so on. In these many fields, it is everywhere. ^[1]

We recommend that beginners in photography do not have to buy any lenses other than the set of lenses already equipped on the camera during the photography learning phase. When you become a "master" in the future, consider a longer focal length lens. Even then, unless there are special needs for telephoto lenses and funding is not a problem, we recommend not considering any lens over 200mm. If you need a telephoto lens occasionally, consider adding one

First, high-quality telephoto lenses are expensive.

Second, telephoto lenses are often large and bulky.

Third, the longer the focal length of the lens, the more stable the camera must be to avoid image blur.

Fourth, no matter how perfect the telephoto lens optical system is, when shooting distant objects, the image is always full of dust, haze and heat waves. Only in very rare clear air can a particularly sharp telephoto image be obtained. ^[2]