A. Air valve. B. Button for varying photographing speed during exposure. C. Exposure button.
The Compressed Air Reservoirs of the "Aeroscope" Camera.
One charge is sufficient to expose 600 feet of film.
But perhaps the most unnerving and difficult conditions under which moving-pictures can be taken are those pertaining to the filming of wild animal life at close range under natural conditions. In this case a good nerve, a steady hand, and acute presence of mind, are indispensable. A wild elephant trumpeting madly and dashing towards the camera at full speed, or a lion springing towards the operator may form the subject for a thrilling incident in a film, but does not inspire confidence in the cinematographer. Under such conditions a tripod outfit is worse than useless. It not only endangers the operator's life, but the pictures taken under such conditions are invariably of poor quality, even if they survive the results of the animal's mad frenzy. To stand one's ground and to keep turning the camera handle steadily at two revolutions per second up to the last moment with the sang-froid of someone filming a street procession would put too great a strain on human nature. Even the coolest man would not obtain first-class results at uncomfortably close quarters. Instead of turning the handle in a steady rhythmic manner the motion would be in a series of erratic jerks, some fast and some slow, producing a result which the public would ridicule. Mr. Cherry Kearton, whose pictures of jungle life constitute some of the marvels of the cinematographic art, considers that this branch of cinematography cannot be excelled for thrilling excitement. The operator must stand his ground undismayed, because the close-quarter pictures are always the most fascinating. Yet at the same time he must keep a corner of one eye fixed upon an avenue of retreat, so that he can get clear in the nick of time when the crisis arises. The attention given to the photographic work must be reduced to the absolute minimum, so as to be practically automatic; the camera must be as small and as compact as possible, for the only way of escape lies often up a tree.
Several inventors have devoted their energies to the evolution of a reliable hand-camera, capable of fulfilling the same duty in cinematography as the snap-shot instrument in still-life work. The tripod was sacrificed, but then there arose another difficulty. This was in the necessity of moving the film mechanism by means of the handle. In fact, under many conditions of working, such as in the jungle, it would be quite impracticable. What was required was an efficient moving-picture machine, small, light, and compact, working upon the principle of "you-press-the-button-and-I'll-do-the-rest."
It is a perplexing problem to solve, and the first commercially practicable idea in this direction was conceived by the Polish scientist Kasimir de Proszynski. He has produced a camera completely self-contained and wholly automatic in its operation. Dimensions and weight have been kept down. In loaded condition, with 300 feet of film, it is 12 inches long, 8½ inches wide, 6½ inches deep, and weighs only 14 pounds. It works upon the "press-the-button" system, the film-moving mechanism and shutter running the whole time the button is depressed. The power comes from cylinders of compressed air by which a tiny engine is driven. All that the operator has to do is to sight his subject and to keep his finger on the button, while he follows the object on the view finder.
When this camera, known as the "aeroscope," appeared upon the market, it aroused considerable interest, but its reliability was doubted. It was not until Mr. Cherry Kearton decided to give it a trial that it came to be regarded more seriously as a feasible moving-picture machine. This naturalist-cinematographer took it with him on one of his expeditions, and was able to record some startling incidents which would not have been possible otherwise. Familiarity with the camera and experience in the field convinced him of its serviceability, provided that certain modifications were effected. These were carried out, and the camera is now regarded as an excellent instrument for work that could not be achieved by any other machine.
It is fitted, as has been said, with a small engine driven by compressed air. The air is stored in six small cylinders of an aggregate capacity of 600 feet. This is sufficient to expose 600 feet of film. The cylinders are charged with air in the manner of a motor tyre and with a similar kind of pump. An indicator on the side shows constantly the air pressure remaining in the reservoirs, while a regulator enables the speed to be varied. The driving mechanism is very light, small, and compact, and contains but a small number of parts, so that the risk of failure is not great. Though it constitutes the most delicate part of the whole mechanism, and requires careful handling, it works remarkably well so long as it is kept clean and well lubricated.