Photography Terminology - What Is a Zoom Lens

Zoom lenses are typically utilized on binoculars and cameras to make objects that are far from us appear to be closer. This means that zoom lenses are utilized to change the focal length, which is the distance at which the focus, as indicated by the letter F from the convex or concave mirror’s pole on the image. These zoom lenses are called para focal lenses since they are able to ensure the focus of an image even when altering your focal length.

The characteristics from the zoom lens

These lenses possess these characteristics:

1. The lenses are able to be zoomed from 400x up to 300x. A 300x zoom is typically required for TV cameras, while SLR cameras are able to be zoomed as high as 50x. The other cameras are able to be zoomed at least 5x.

2. It is important to note that the quality of a picture is unaffected when taken with these lenses. That is, the greater percentage of length to the focal length is, the greater the image quality.

3. There are a variety of these lenses that are available on the market. There are a few of them some of them:

a. Long focal lenses These lenses are usually utilized in cameras. The name itself suggests that they have a focal length greater than normal lenses.

b. Lenses with wide focal lengths – These kinds of lenses are typically employed in cinematography. The name of the lens suggests that they are smaller in length than the normal lens.

4. Certain digital cameras with long focal lenses offer an enlargement and cropping facility to the image that is captured. This method used by digital cameras is referred to as digital zooming. The picture generated by digital zooming is of low optical resolution.

5. They have an afocal structure. The system doesn’t produce any kind of convergence or divergence. This system can be employed as a telescope in order to build reflecting or refractive telescopes.

How does a zoom lens work

A zoom lens may be split into 2 parts:

a. A lens that has an unassisted focal length.

b. Afocal zoom that includes fixed and moveable lenses. In this method, light is not focused. However, the beam’s size can be altered. In this case, the beam size is the amount of light that passes through the lens. In this setup, the two lenses are convex: L1 and L3, which can be separated with a concave lens L2.

Two convex lenses share the same focal lengths. A concave lens is able to have a focal distance of less than half the lens’ focal length. Only L1 and 2 are moving while the lens remains fixed. The lens L2 is able to move from front to back of the lens while the lens L1 initially shifts forward before moving backward from the lens L3 as the parabola. The distance of focus is altered.


All in all, zoom lenses are frequently used by photographers in order to create better quality photographs or images. They are offered at affordable and reasonable prices. The lenses’ construction is also more simple to make, and different designs of these lenses are on offer in the market.