Patent ID: 7161629

Claim:
A method of calculating an optimum exposure amount of an electronic camera in a short period after beginning a prepare operation of exposure, the electronic camera having a photoreceptor device that receives light from a subject and outputs signals corresponding to an image of the subject, the method comprising the steps of: performing a first exposure operation of the photoreceptor device at a fixed first exposure amount after insecurity period of the photoreceptor device from beginning a prepare operation of exposure to obtain a first output, the fixed first exposure amount being set without calculating the fixed first exposure amount; performing a second exposure operation of the photoreceptor at a fixed second exposure amount after the first exposure operation to obtain a second output, the fixed second exposure amount being set without calculating the fixed second exposure amount; calculating a first signal level based on the first output; calculating a second signal level based on the second output; comparing the first signal level with the second signal level and selecting the signal level closest to a predetermined exposure amount as a selected exposure amount; determining an optimum exposure amount by changing the selected exposure amount by a prescribed amount smaller than a difference between the fixed first exposure amount and the fixed second exposure amount; and performing an optimum exposure operation of the photoreceptor device at the determined optimum exposure amount for recording the image.