A zoom is a change in focal length achieved by adjusting a variable focal length lens, making a subject appear closer or further away without physically moving the camera. Zooming in increases the focal length, narrowing the field of view and magnifying the subject; zooming out decreases it, widening the field of view and reducing the apparent size of subjects within the frame. Unlike a push in or pull back which involves physical camera movement, a zoom changes only the optical properties of the lens.

The visual difference between a zoom and a dolly move is subtle but perceptible and carries different aesthetic qualities. A zoom compresses perspective as the focal length increases, flattening spatial relationships between foreground and background in a way that physical camera movement does not. A dolly move shifts the parallax relationship between near and far elements, creating a genuine sense of moving through space. Zoom lenses that combine focal length changes with physical movement - the Vertigo effect or dolly zoom, where the camera moves physically as the zoom changes to keep the subject constant size while the background scales - exploit this perceptual difference to create a distinctive, disorienting effect. In contemporary filmmaking, zooms are more often used as deliberate stylistic choices that reference documentary, 1970s cinema, or observational aesthetics rather than as primary compositional tools.

When prompting AI video generation, "zoom in" and "zoom out" are well-understood instructions that typically produce the intended optical magnification effect. Specifying the speed and degree of the zoom alongside the subject helps generate footage with the intended scale change and pacing, whether a slow, deliberate zoom that builds tension or a rapid zoom for punctuation and energy.