Adding a Zoom Blur

The shot you've just keyed was created with a technique called ramping, in which the speed of the footage changes over time. It's equivalent to adjusting the crank of a 35mm film camera. As a result, the zoom in and zoom out look stilted—the natural blur that would occur from such a fast zoom isn't visible in the shot. No problem. We'll add our own blur.

The blur should affect the entire shot, so we'll need to apply the filter to a master layer containing everything.