Patent ID: 6222622
Filing Date: 2001-04-24
Classification: G03B

Abstract:
A photometering apparatus for a camera that mounts a plurality of types of photographing lenses and mounts a plurality of types of focusing plates, comprising:a split photodetector that measures photometering values;a discrimination device for discriminating a type of a mounted focusing plate;a processing unit that determines a type of a mounted photographing lens;at least one memory for storing:a predetermined number of said types of focusing plates and corresponding photometering correction constants for each type of focusing plate;a predetermined number of photometering modes for each type of focusing plate, including a spot beam photometering mode;permissible photometering modes for each type of focusing plate;a calculation device that calculates measurement correction values according to each type of focusing plate stored in said memory, includinga photometering correction value selector that selects a photometering correction value for the type of the mounted focusing plate when a first type of mounted photographing lens is determined;an open F-number level correction calculator that selects an open F-number level correction when a second type of mounted photographing lens is determined; anda weighting device for, when neither said first type nor said second type of mounted photographing lens is determined, weighting a photometering value measured by the split photodetector according to:a focal length of the mounted photographing lens;a position of an exit pupil of the mounted photographing lens;a vignetting factor of the mounted photographing lens; anda photometering error determined by a minimum diaphragm value of the type of the mounted photographing lens and the type of the mounted focusing plate; anda photometering selector for, when the spot beam photometering mode is selected, selecting, according to the type of said focusing plate, one of a narrow field center sensor spot photometering operation, a wide field center sensor spot photometering operation, and a center-weighted photometering operation.