The “dolly zoom,” also known as the “Hitchcock zoom” or “Vertigo effect,” is a filmmaking technique that involves changing a zoom lens’ angle of view while moving the camera toward or away from a subject to keep their relative size in the frame the same. Here’s a 4-minute video by Now You See It that explains this technique and how (and why) it’s used.
“The Dolly Zoom is a bizarre cinematic effect, and it can do a lot more than just make you dizzy,” writes narrator Jack Nugent. “Let’s take a look at some famous instances of the dolly zoom, see what they accomplish, and explore how it teaches a lot of principles of filmmaking.”
On the still photography side of things, the dolly zoom against a blank background has been used to show how different lens focal lengths and camera distances affect how faces look in portraits — it’s an explanation of how the camera “adds 10 pounds.” Here’s an example animated GIF by photographer Dan Vojtech that went viral last year:
The dolly zoom is called the “Hitchcock zoom” and “Vertigo effect” because it was popularized by filmmaker Alfred Hitchcock in his 1958 film Vertigo, which used the technique to covey the disorienting effects of vertigo.