Rack focus is the technique of shifting the camera's focus point from one subject or depth plane to another during a shot, causing one element to transition from sharp to blurred while another moves from soft to sharp. The terms rack focus and pull focus are used interchangeably in professional production, both referring to this deliberate mid-shot change in the point of focus.

The technique requires precise control of the lens focus, either through manual focus pulling by a dedicated focus puller working in coordination with the camera operator, or through electronically controlled follow focus systems. A well-executed rack focus happens at a dramatically or narratively appropriate moment - shifting focus to a character who enters a conversation, revealing a previously soft background element that becomes important, or redirecting attention from one subject to another as the emotional weight of the scene transfers. The shallow depth of field required for an effective rack focus means the technique is associated with longer focal lengths and wider apertures, where the focus transition between planes is visually dramatic. When done precisely, rack focus is nearly invisible as a technical act and reads purely as a natural redirect of the viewer's attention.

When prompting AI video generation for rack focus effects, describing the before and after states of the focus shift as clearly as possible helps communicate the intended result. Specifying which subject starts sharp and which ends sharp, the approximate timing of the shift, and the scene context gives the model the clearest possible brief for this technically specific camera technique.