The adjustment of focal length during a shot, which changes the apparent distance from a subject. From a technical perspective, zooms are accomplished by using special zoom lenses. Sometimes a zoom is used instead of a tracking shot, but in contrast to the latter, the camera in a zoom shot normally remains stationary. In both types of shots there is a similar change in apparent distance from the subject. However, there are notable differences in the relationship between the subject and the background. In zoom shots, the relative positions and sizes of the elements in the frame stay the same, whereas in a tracking shot, the relationship between these elements changes. In other words, a zoom doesn’t cause changes in perspective whereas a tracking shot does. In addition, it is worth noting that a zoom has no counterpart in the human visual system, whereas a tracking shot is analogous to the perspective changes associated with natural human movement. A zoom has two possible directions, zoom in and zoom out. When combined with a tracking shot, a zoom can become a dolly zoom.
