What is a zoom lens?

The lens enlarges from far to near, which is called zoom lens;

Zoom lens is a kind of camera lens that can change the focal length in a certain range, so as to get different field of view, different images and different scene ranges. Zoom lens can change the shooting range by changing the focal length without changing the shooting distance, so it is very beneficial to picture composition. Because a zoom lens can also serve as several fixed-focus lenses, it not only reduces the number of photographic equipment to carry when traveling, but also saves the time for changing lenses.