Tim Moynihan explains how the in-camera dolly zoom, a.k.a. the famous shot Hitchcock used in Vertigo, works.
He writes, "To understand the perspective distortion you see in these shots, all you need is a camera with an optical zoom lens, a still-life subject, a nice deep background scene, and, ideally, a grid-pattern overlay for shot composition. First, take a picture of the still-life subject with the lens at its widest-angle setting, and make note of how big the still life looks on the grid-pattern overlay. Next, back up about 5 to 10 steps, zoom in so that the still-life subject has the same size and placement in the frame as the first shot, and take another picture."
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