Patent ID: 6826364
Filing Date: 2004-11-30
Classification: G03B,H05B

Abstract:
A zoom flash comprising:a light emitter; a zoom driver which moves said light emitter along an axis to vaiy an illumination angle; a detector which detects a zoom position of said light emitter; a calculator which calculates a pre-flash emission level according to the detected zoom position so that iliuminance on an object at a predetermined distance is substantially constant regardless of a variation of said illumination angle; a controller which activates said light emitter to emit a preliminary flash emission, before a main flash emission, by supplying a voltage corresponding to said pre-flash emission level for said light emitter; and a memory in which a maximum guide number that varies in accordance with said zoom position, a constant predetermined reference guide number, and a predetermined reference flash emission level serving as a correction constant are stored, wherein said maximum guide number, said reference guide number, and said reference flash emission level are stored in said memory, and wherein said calculator calculates a pre-flash emission level using a predetermined relationship between the reference flash emission level, the reference guide number and the maximum guide number corresponding to the detected zoom position.