| 摘要 |
PURPOSE:To obtain a photograph with preset concentration by setting the film concentration set point at the photo-timer automatic photography to the function of the ratio between the peak and average value in the period which corresponding to the photo-timer signal detection range for the image signals of a television equipment. CONSTITUTION:The output of a amplifier 4 which amplifies image signals is input to the peak hold circuit 7 and the wave heightness value of the image signals which correspond to the detection range between every television fields is retained. The output of the amplifier 4 is also fed into the average value circuit 8 while fluoroscopy images are obserbed and the average value of the image signals is obtained. The wave height value of the image signals and their average value are divided in the division circuit A2 and are multiplied by the DC voltage set by the film concentration setting device VR in the multiplication circuit A3. The result is fed into the comparator A1 of the photo-timer as the film concentration set point at the time of photography. |
