The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Oct. 03, 1978
Filed:
Jan. 27, 1977
Hidekazu Okajima, Kawasaki, JP;
Hideto Iwama, Kawasaki, JP;
Canon Kabushiki Kaisha, Tokyo, JP;
Abstract
A light metering system for a photographic camera which may be selectively operated in a through-the-lens (TTL) light metering mode or an outside-the-lens (OTL) light metering mode to improve the exposure control accuracy over an extended range of light levels particularly towards the low light level side. In one embodiment, the light metering system employs a single light value sensing element in combination with light path changeover means arranged upon movement to change over the light metering aspect between the TTL and OTL light metering modes. In another embodiment, there is provided two light value sensing elements of different light response characteristics from each other for adaptation to the respective light metering modes in combination with a circuit transfer switch operable to select either the TTL light metering mode or the OTL light metering mode. With a camera equipped with a shutter preselection automatic exposure control range and a diaphragm preselection automatic exposure control range, it is possible to realize suitable combinations of the exposure control modes with the light metering modes.