| 摘要 |
PURPOSE:To prevent the delay of operation by providing a means which determines temporarily a specific aperture value between a previously specified proper aperture value and an open aperture value, and selecting the proper aperture value of an electromagnetic stop mechanism and a specific aperture value. CONSTITUTION:Brightness information BV obtained from light from a subject through the photoelectric conversion 2b of an optical system 2, a signal SV based upon ASA information on a photosensitive body, and information TV obtained by setting 4 a shutter speed are inputted to a proper aperture value determining circuit 5. The temporary aperture value is determined with the output AV1 of the determining circuit 5 and inputted as a signal V0 to a stop mechanism driving circuit 9 through a changeover switch 8 and the stop mechanism 1b of the optical system 1 is controlled to the temporary aperture value. Then when a shutter 7 is pressed, the proper aperture value AV1 is inputted to a stop mechanism driving circuit 9 through the changeover switch 8 and the stop mechanism 1b is controlled to move back a half-mirror 1c, thereby exposing a film 1d. Consequently, the delay of operation of the stop mechanism 1b is prevented to perform proper exposure. |
