HIGH-SPEED CINEMATOGRAPHY IN HIGHER EDUCATION AND RESEARCH

Abstract

This chapter discusses the aspects of high-speed cinematography and the functioning of a typical high-speed rotating-prism camera; it discusses the path of light that travels through a rotating-prism camera. In time-lapse cinematography, a series of pictures is exposed at a slower rate than that at which they are later projected, producing a speeding-up of motion because of a compression of the time-scale. However, in high-speed cinematography, the camera taking speed is higher than the projection speed, producing an apparent slowing down of motion because of the expansion of the time-scale. High-speed cameras can conveniently be grouped in three categories: (1) intermittent movement cameras working at speeds between 64 and 500 frame/sec, (2) rotating-prism cameras working at speeds between 150 and 20,000 frame/sec, and (3) rotating-mirror cameras working at speeds between 200,000 and 20,000,000 frame/sec. Intermittent cameras work on a similar principle to the better designs of ordinary-speed cameras. The film is pulled down frame by frame by a claw mechanism and a register pin is engaged to hold the film steady and in frame register at the moment of exposure. The biggest industrial users of high-speed cinematography in the United Kingdom and in Continental Europe are the electrical industries, aircraft manufacturers, the motor industry, and companies concerned with designing and manufacturing production machinery. Each of these industries accounts for about 20% of the total number of rotating-prism cameras sold. The remaining 20% is spread around the textile industry, paper makers, and the oil companies. The ultra-high-speed cameras of the rotating-mirror type are used almost exclusively by research laboratories concerned with either plasma research or explosives.