PHOTOMETRIC APPARATUS

PURPOSE:To make it possible to perform measurement easily by detecting the flashing frequency of a light source L, and automatically setting the sampling time for a photoelectric output adequately in response to the flashing frequency. CONSTITUTION:The light of a light source L is flashing at an unknown frequency. A light receiving part 2 receives the light and imparts the voltage of a photoelectric output 6 to a comparator 3. A slice-level setting means 1 imparts the voltage of a specified slice level 8 to the comparator 3. Both voltages are compared in the comparator 3. Thus, the pulse-shaped comparator output 7 is generated. The output 7 is inputted into a counter 4. The counter 4 counts the number of the pulse-shaped outputs 7 within a specified time. Thus, the counter 4 can obtain the flashing frequency of the light source L based on the relationship between the specified time and the number of the outputs 7 of the comparator. An integrating means 5 automatically sets the sampling time in response to the flashing frequency, and the photoelectric output 6 is sampled. Thus, the flashing light of the light source L can be measured.