Zooming in or out is done with a single lens, magnifying the main subject or decreasing the main subject within the frame. If we zoom in, we are, in effect a voyeur zeroing in on a subject. A moving POV shot. Zooming out starts with some subject or detail and then puts it into context in the finishing wide shot. Zooming out is often used to give us a sense of geography. However, the zoom lens tends to flatten the image.
Very few filmmakers utilize the zoom lens to great effect as Stanley Kubrick. In the first shot from BARRY LYNDON, he starts on Barry Lyndon and then zooms in to what he’s observing, the Baroness and then pans as Barry does, following the Baroness.
The second clip from A CLOCKWORK ORANGE starts extremely tight and pulls back to show us Alex and his Droogs at the milk bar.