The camera lens zooms in on the subject, while the camera itself is physically moved away from it, or vice versa. This effectively changes the focal length of the lens without altering the image composition. This causes the image's depth information to either compress or stretch, making the image look like it's getting deeper or flatter. Goes by many names, including optical compression, tracking zoom, dolly zoom, Hitchcock zoom, contra-zoom, trombone shot, and push-pull zoom. Compare Whooshing Credits. Examples of Vertigo Effect include: