CHAPTER VII

HAND-HELD CAMERAS FOR AERIAL WORK

=Field of Use.=—The first cameras to be used for aerial photography were hand-held ones of ordinary commercial types. Indeed the idea is still prevalent that to obtain aerial photographs the aviator merely leans over the side with the folding pocket camera of the department store show window and presses the button. But the Great War had not lasted long before the ordinary bellows focussing hand camera was replaced by the rigid-body fixed-focus form, equipped with handles or pistol grip for better holding in the high wind made by the plane's progress through the air. Even this phase of aerial photography was comparatively short-lived. The need for cameras of great focal length, and the need for apparatus demanding the minimum of the pilot's or observer's attention, both tended to relegate hand-held cameras to second place, so that they were comparatively little used in the later periods of the war.

Yet for certain purposes they have great value. They can be used in any plane for taking oblique views, and for taking verticals, in any plane in which an opening for unobstructed view can be made in the floor of the observer's cockpit. They can be quickly pointed in any desired direction, thus reducing to a minimum the necessary maneuvering of the plane, a real advantage when under attack by “Archies” or in working under adverse weather conditions.

For peace-time mapping work the hand-held camera, when equipped with spirit-levels on top, and when worked by a skilful operator, possesses some advantages over anything short of an automatically stabilized camera. For experimental testing of plates, filters and various accessories, the ready accessibility of all its parts makes the hand-held camera the easiest and most satisfactory of instruments.

The limitations of the hand-held camera lie in its necessary restriction to small plate sizes and short focal lengths, and in the fact that it must occupy the entire attention of the observer while pictures are being taken—the latter a serious objection only in war-time.

=Essential Characteristics.=—In addition to the general requirements as to lens, shutter and magazine, common to all aerial cameras, the hand camera must meet the special problems introduced by holding in the hands, especially over the top of the plane's cockpit. An exceptionally good system of handles or grips must be provided whereby the camera can be pointed when pictures are taken, and held while plates are being changed and the shutter set. The weight and balance of the camera must be correct within narrow limits; the wind resistance must be as small as possible; the shutter release must be arranged so as to give no jerk or tilt to the camera in exposing.

As to the method of holding the camera, a favorite at first among military men was the pistol grip, with a trigger shutter release (Fig. 37). Because of the size and weight of the camera the pistol grip alone was an inadequate means of support and additional handles on the side or bottom had to be provided for the left hand. Small (8 × 12 cm.) pistol grip cameras were used to some extent by the Germans (Fig. 42), and a number of 4 × 5 inch experimental cameras of this type were built for the American Air Service (Fig. 37). But the grasp obtained with such a design is not so good as is obtained with handles on each side or with flat straps to go over the hands. The camera balances best with the handles in the plane of the center of gravity. As to weight, no set rules are laid down, but experience has shown that a fairly heavy camera—as heavy as is convenient to handle—will hold steadier than a light one. The American 4 × 5 inch cameras described below weigh with their magazines in the neighborhood of twelve pounds.

=Representative Types of Hand-held Cameras.=—French and German hand-held cameras are essentially smaller editions of their standard long-focus cameras, and a description of them will apply to a considerable extent to the large cameras to be discussed in a later chapter. The English and American hand-held cameras are generally quite different in type from the large ones, which are used attached to the plane.

_The French hand-held camera_ uses 13 × 18 centimeter plates, carried in a deMaria magazine, and has a lens of 26 centimeters focus. The shutter is the Klopcic self-capping type already described, and is removable. The camera body, built of sheet aluminum, takes a pyramidal shape. In Fig. 38, _A_ is the shutter release and _B_ the rectangular sight, of which _C_ is the rear or eye sight. The complete sight may be placed either on the top or on the bottom of the camera. At _D_ are the handles, sloping forward from top to bottom; _E_ is a catch for holding the magazine; _F_ is a door for reaching the back of the lens and the lens flap; _G_ is a snap clasp for holding the front door of the camera closed; _H_ is a ring for attaching a strap to go around the observer's neck; _I_ is the lever which opens the flap behind the lens and releases the focal-plane shutter; _J_ is a snap catch for holding the front door of the camera open.

The operations with this camera are three in number. Starting immediately after the exposure, the camera is pointed lens upward and the plate changed by pulling the inner body of the magazine out and then in; next the shutter is set; then the camera is pointed, and finally exposed by a gentle pull on the exposing lever.

_The English hand-held camera_ (Fig. 186). This differs from the French in the size of plate (4 × 5 inch), in the shape of the camera body, which is circular, and in the type of shutter, which is fixed-tension variable-opening. In the longer focus camera (10 to 12 inch) the shutter is self-capping, and the aperture is controlled by a thumb-screw at the side. In the smaller (6 inch) a lens flap is provided in front of the lens and the shutter aperture is varied by a sliding saddle and cord. The handles of the camera are placed vertical, instead of sloping as in the French. The shutter is released by a thumb-actuated lever. Double dark slides are used, as the multiple plate magazine has not found favor in the English service.

_The German hand-held camera_ (Fig. 42). The German hand-held camera is, like their whole series, built of canvas-covered wood, the body having an octagonal cross-section. It is equipped with the Ica shutter and uses the Ernemann six plate (13 × 18 cm.) magazine. The excellent system of grips by which the camera is held and pointed is an especially commendable feature. On the right-hand side is a handle similar to the French type, but carefully shaped to fit the hand. The left-hand grip consists of a long, rounded block of wood running diagonally from top to bottom of the side, with a deep groove on the forward side for the finger tips, while over the hand is stretched a leather strap, the whole aim being to provide an absolutely sure and comfortable hold on the camera during the plate changing and shutter setting operations.

_United States Air Service hand cameras._ The hand camera developed for the United States Air Service and manufactured by the Eastman Kodak Co. is made in three models, using the bag magazine, a two-compartment magazine, and roll film, respectively. The shutter is of the fixed (one or two) aperture variable tension type, built into the camera. A distinctive feature is the double lens flap, in front of the lens actuated by the thumb pressure shutter release (Fig. 39). In the bag magazine camera the shutter is set, as a separate operation, by a wing handle, and a similar handle controls the tension adjustment. In the two-compartment type (Fig. 33) the shutter wind-up is geared to the plate changing lever, so that but one operation is necessary to prepare the camera for exposure. In the film type (Fig. 34) a single lever motion sets the shutter and winds up the film ready for the next exposure. After the last exposure of all the film is wound backward on its own (feeding) roller before removing from the camera. The film is held flat by a closely fitting metal plate behind, and by guides at the edges in front, an arrangement which with small sizes works fairly well although the exquisite sharpness of focus attainable with plates is not to be expected. The saving in weight made possible by the use of film in place of plates in metal sheaths is about three pounds per dozen exposures.

In all these cameras the sight—a tube with front and back cross wires—is placed at the bottom. This position has been found the most convenient for airplane work, as it necessitates the observer raising himself but little above the cockpit, a matter of prime importance when the tremendous drive of the wind is taken into account.