Measuring the Action of Between-Lens Shutters of Cameras

Abstract

The widespread use of synchronized flashlight has made it more important to have exact knowledge of the action of camera shutters. Of the many existing methods of measuring the opening time of camera shutters, the clearest and most accurate results are obtained by using the cathode ray oscilloscope. There are two basic methods. In the one, the shutter to be studied is mounted in a camera with which a photograph is taken of the path traced on the oscilloscope screen by the spot travelling at a known speed. In the other method the shutter is mounted between a light source and a photocell. During the opening of the shutter, light falls on the photocell. The cell then delivers a proportional voltage which serves to deflect the spot vertically. By simultaneously deflecting the spot in the horizontal direction with a voltage linear with time, a complete picture of the shutter action and time function appears on the screen.