rack focusing

Rack focusing refers to an on-screen film technique of focus change that blurs the focal planes in sequence, forcing the viewer's eye to travel to those areas of an image that remain in sharp focus; the focus changes from an object in the foreground to an object in the background or vice versa, to direct, shift, and steer the attention of the viewer forcibly from one subject to another. Also known as "selective focusing" or "pull focus."