Abstract

HIGH-SPEED cinematography, that is, a camera operating at speeds up to 3,000 pictures per second, presents special lighting problems as compared with the more conventional speed of 24 frames per second normally used for ciné-film photography. The light intensity for a satisfactory exposure to be made at these high speeds is approximately proportional to the ratio of frames per second, and with an average object having a reflectivity of 10 per cent, the illumination required is about 10,000 foot-candles for a lens aperture of f 2.7. However, at higher speeds the total exposure-time seldom exceeds 3 seconds, and it is therefore possible to consider other means of obtaining these very high intensities than by ordinary methods.