Another prominent feature of the mechanism is what is termed an equilibrator. Practically speaking this is a small gyroscope, and is introduced to subdue any small vibrations or tremblings which arise while the instrument is working. This part of the mechanism has been criticized on the ground that a gyroscope, to be effective, must be of appreciable weight. Many operators dispute the necessity for its introduction. They point out that the beneficial effects are not proportionate to the extra weight involved. Furthermore, being an additional piece of mechanism, it enhances the risk of derangement. Against these contentions, however, the operators who have worked the instrument maintain that it nullifies all the vibrations set up by the driving mechanism, which, though apparently slight, would otherwise suffice to spoil the pictures. Seeing that the sole object of employing this camera is the elimination of a rigid support such as a tripod, it certainly seems worth while, even at the cost of added weight, to gain some compensating steadiness. And the vibration of the air engine increases the need.
The Lens, Shutter, Compressed Air-driven Mechanism, and Gyroscope, which counteracts slight Vibrations, of the "Aeroscope."
Loading the "Aeroscope" Camera.
The unexposed and exposed film-boxes are mounted upon one spindle.
In operating this instrument the usual method is to hold the camera against the chest and one cheek, thereby bringing the eye on a level with the sighting piece. By letting the elbows rest against the body the weight is easily and steadily supported. Held in this position the minimum of fatigue is felt by the cinematographer, while he is given complete control over the mechanism. It can also be used when the operator is on horseback, the method of support being virtually the same. But in this case only one hand is used; the other is left free to control the horse. Another advantage of the system is the ease with which the camera can be swung round in order to follow a moving object steadily.
Photographers who use a hand-camera are familiar with the disturbances set up by the motion of the body in breathing. This is often sufficient to spoil a picture if care is not displayed at the instant of exposure. With the aeroscope—owing to the exposure being from 1/32 to 1/50 of a second, relatively long in comparison with snap-shotting where the exposure is often only the 1/200, or even less, of a second—these disturbances are somewhat more acute. Considerable practice is required before this difficulty can be overcome. Some operators who have used the aeroscope prefer to utilise a convenient support, if available, such as a wall, or the stump of a tree, thereby making sure of a solid rigid foundation. But in cinematography the ill-effects arising from respiration are not so serious as in still-life work. A picture here and there may show its effects, but they pass unnoticed. They are subdued, as it were, by the unblemished pictures which precede and follow.
Another camera of this type is the "Jury Autocam" which, as its name implies, works upon the automatic "press-the-button" system. This camera is fitted with a small electric motor, driven by a small dry battery, and brought into action by the pressure of a button. A small side-lever controls the picture-taking speed, which can be varied while the mechanism is running. The camera itself is exactly similar to the "Jury Duplex" model, the only addition being a small separate case, about 2 inches in depth, fitted to the base of the instrument, and a covered chain gearing on one side for transmitting the power from the motor to the camera mechanism. This camera likewise is fitted with a small balancing apparatus to counteract slight vibrations.