Photographic camera with state-of-focus indication

US4344686A · kind A · utility

Assignee

• Agfa-Gevaert NV · BE

Inventors

• Otto Stemme · Munich, DE
• Peter Lermann · Feldkirchen-Westerham, DE
• Istvan Cocron · Munich, DE

Key dates

• Filing date: Mar 24, 1980
• Grant date: Aug 17, 1982
• Expiry date: Mar 24, 2000

Classification

• Technology area (CPC G): Physics
• CPC primary: G03B13/18
• WIPO field: Optics
• WIPO sector: Instruments

Abstract

A photographic still or motion-picture camera has a viewfinder and a manually moved focus adjuster, such as a focussing ring. When the user peers into the viewfinder, there is a visible indication of the direction in which the focus adjuster should be manually moved to reduce the state-of-focus error, for example two curved illuminated errors, one pointing clockwise and the other counterclockwise, only one of which lights up to indicate the direction in which the focussing ring should be manually turned. When the state-of-focus error has been reduced to zero or a minimum, this is likewise indicated, for example because neither curved arrow is illuminated. To control the activation of the indicating elements, use can be made of components of a conventional completely automatic focussing system, but minus the adjusting motor of such system and minus superfluous motor-energization control circuitry. In this way, the user is provided a simple and unequivocal guide when manually focussing, without the cost, complexity, bulkiness and power consumption of a complete automatic focussing system including an adjusting motor and motor-energization control circuitry.