Clarence A Clark

US Patent:

50271431, Jun 25, 1991

Filed:

Dec 29, 1989

Appl. No.:

7/459074

Inventors:

Clarence R. Clark - Denver CO
David W. Sanso - Lakewood CO

International Classification:

G03B 506
G03B 508
G03B 1910

US Classification:

354160

Abstract:

A preferred embodiment of a photographic camera comprises a lens standard supporting an optical lens and a screen standard supporting an image screen. At least one of the lens standard and screen standard is movable to vary a distance along the longitudinal camera axis by which they are separated, and one of the lens and screen is rotatable about an axis normal to its optical axis. A reel means, including a drum rotatable about a drum axis for coiling a flexible extension member, is fixed in geometric relation to one of the standards. Rotation signaling means generates a rotation signal in response to rotation of the drum means. A distal end portion of the flexible extension member is fixed in relation to the other of the standards such that, when the distance is decreased or increased, the drum means is caused to rotate about the drum axis. A computer receives the rotational signal and computes a length indicative of a difference in the length by which the first and second standard are separated when a first and second point in the object plane are brought into focus on the image screen and computes an angle through which the lens or screen must be rotated to bring the complete object plane into focus in compliance with Sheimpflug's law.