A shutter tester using a photo-electric integrator

The requirements for testing between-lens camera shutters are discussed and it is concluded that an ideal instrument should combine a photoelectric integrator with a single-sweep oscilloscope, the two units operating simultaneously. The instrument described uses a valve voltmeter to measure the voltage across the integrating capacitor. Methods of calibrating the circuit are given. The cathode-ray oscilloscope employs a phantastron time base; time marking facilities are provided. The integrator measures the effective exposure time and the oscilloscope shows the total open time of the shutter besides indicating faults such as sticking or bouncing of the shutter blades.