Glossary: Push In (PUSH IN: as written in a Shooting Script)

The Push In Shot in contrast to Zoom is when the camera physically moves towards a subject, usually on a Dolly and does not use an Optical Zoom changing the Focal Length.

see also "Dolly Zoom" effect achieved by using the setting of a Zoom lens to adjust the angle of view (often referred to as field of view) while the camera dollies (or moves) towards or away from the subject in such a way as to keep the subject the same size in the frame throughout. In its classic form, the camera is pulled away from a subject whilst the lens zooms in, or vice-versa. Thus, during the Zoom, there is a continuous perspective distortion, the most directly noticeable feature being that the background appears to change size relative to the subject.