| 摘要 |
PURPOSE:To obtain a stable exposure through a whole picture plane by calculating an illuminance in respective scanning positions from an exposure quantity signal corresponding to a luminance of a central section of an optical image of an object and controlling a gain of an amplifier circuit corresponding to the calculated result. CONSTITUTION:In a microcomputer 15 (called micon hereinafter) of a controller 13, a light quantity lowering rate A, a diameter of a lens d, an image distance S and an angle of field a with respect to respective scanning positions of an image pick up element 6 are previously stored. A luminance signal 23 from a signal processing circuit 9 is gated in a photometry circuit 11 and a signal of a central section of an object to be phtographed is taken out and this signal is inputted to an A/D converter 14 as an exposure signal 25 through an integrating circuit 12. The microcomputer 15 receives said exposure signal and calculates an estimated value B of the luminance from a diaphragm measured value through a diaphragm driver and calculates an estimated value E of the illumination of the respective scanning positions form the estimated value B of the luminance, and previously stored light quantity lowering rate A, a diameter d of a lens, an image distance S, and an angle of field a. Based on this estimated value E of the illumination, a gain of an amplifier circuit 8 is controlled. |
