| 摘要 |
PURPOSE:To ensure lighting contrast by using a photometric circuit, an integral network, a lighting contrast setter and an arithmetic circuit and then calculate the difference between the flash light volume obtained based on the lighting contrast and the flash light volume obtained through photometry. CONSTITUTION:A photometric circuit consists of a photodetector PD, a logarithm compressing diode D1 and an arithmetic amplifier OA1. The potential obtained by giving a logarithm compression to the intensity of incident light to be applied to the detector PD is extracted. A logarithm compression integral network, consisting of the diodes D2 and D3 plus a capacitor C2, delivers the voltage obtained by giving a logarithm compression to the integral value of the flowed-in current to the circuit itself to the both ends of the capacitor C2. In addition to these circuits, the following components are provided: a lighting contrast setter 5; an arithmetic circuit 3; a display device 7 which displays the value sent from the circuit 3; a display device 8 which shows the difference between the light emission volume of a flashing device which is not shown in the figure and the light emission volume calculated by the circuit 3; a display device 9 which shows the difference of apex value between the area which receives an irradiation of light emitted from the flashing device and the area receiving no irradiation of light; and others. |
