Definition of racking focus in English English dictionary
(Film) Racking focus is the practice of shifting the attention of a viewer of a film or video by changing the focus of the lens from a subject in the foreground to a subject in the background, or vice versa. It dated back to the time when cameras did not have reflex lenses so the operator would have to rack focus the camera by looking through the viewfinder then sliding the camera over so that the shot would be in focus