The IR System: An Optical Method for Increasing Depth of Field

The depth of field of a corrected lens system is determined by its focal length, its relative aperture, and the permissible diameter of the “in-focus” image of a point source. — The limited depth of field in motion picture photography restricts freedom of action in large parts of the set, dictates a stylized, protracted, and costly studio procedure, and affects the dramatic value and audience appeal of monochrome or color pictures. — Previous attempts to increase lens depth of field have been scientifically unsound and unsuccessful in practice. The new IR System, described in this paper, is based on a division of the set into optically appropriate regions, each region having identifiable illumination, with the identification and differential focusing at the camera of all regional images within a single exposure. Thus greatly increased depth of field in straight and process shots becomes available. — By a further modification in regional lighting, a number of such increased-depth takes can be simultaneously made from different distances or at various angles, each such take having its own different and appropriate lighting.

Print ISSN

0097-5834

Published

1942-01

Content type

Original Research

DOI

10.5594/J09934