Focus: The sharpness of an image.

deep focus

Sharp definition of all objects in front of a camera, both far and near, in the same shot. The effective range in which ordinary camera lenses can produce images in focus is limited by the laws of depth of field. But the development of a deep-focus lens late in the '30s opened new possibilities for directors and cameramen. Director of photography Gregg Toland explored those new possibilities with great effectiveness in the '40s, most notably in Orson Welles's CITIZEN KANE (1941) and William Wyler's THE BEST YEARS OF OUR LIVES (1946) By using a deep-focus shot, a director may comment visually on relationships between characters and events situated at different planes without resorting to an interruptive cut or unnecessarily moving his camera to cover the entire scene. See also André Bazin.