Fig. 49.—Italian (Lamperti) single-motion plate camera, on anti-vibration tray.
The limitations set by the between-the-lens shutter in this type have been overcome in an experimental camera along similar lines made by the Premo Works of the Eastman Kodak Company, and in the French Aubry model (Fig. [48]). These employ focal-plane shutters which swing out of the way and are set as the exposed plate swings or drops to the receiving chamber. The dependence on gravity in this type could doubtless be avoided by positive finger mechanisms. If so, the resultant cameras, set and exposed by a single motion, would acquire a highly desirable simplicity of operation. They would have peculiar merit because of the very short interval required between exposures—a characteristic needed for making low stereo-oblique views. The cameras just mentioned have, however, departed far in form from the lines of standardized practice and have not been followed up.
CHAPTER IX
SEMI-AUTOMATIC AERIAL PLATE CAMERAS
In the hand-operated camera the limit to progress is set when the number of operations is reduced to a minimum. In cameras using the larger sizes of plates a reduction in the number of operations almost inevitably results in inflicting considerable muscular labor upon the operator. Furthermore, distance operation becomes difficult to arrange for, because the common reliance—the Bowden wire—is unfitted for heavy loads. Consequently, for setting the shutter and changing the plates we must resort to some other source of power than the observer's arm. Air-driven turbines or propellers have been used on aerial cameras, as well as clock-work, and also electric power, the latter derived either from a generator or from storage batteries. The relative merits of these sources of power form the subject of a separate chapter. Mention only is here made of the form of drive actually employed in connection with the various cameras.
The term semi-automatic camera is best used to designate that type in which the observer (or pilot) has merely to release the shutter, after which the mechanism performs all the operations necessary to prepare for the next exposure. There has been some difference of opinion as to whether it is ever advisable to go further than this with plate cameras. The English Service holds that completely automatic exposing, in addition to plate changing, is apt to encourage the making of many more pictures than necessary, involving carrying an excessive weight of plates. The French Service has rather generally favored entirely automatic cameras in theory, although during the war practically all the work of the French army was done by the hand-operated cameras already described.
The English L Type Camera.—The L, a modification of the earlier C and E models, differs from its predecessors chiefly in the addition of a mechanism which when connected with a suitable source of power can be used whenever desired for changing the plates and setting the shutter. As in the C and E types, all unexposed plates are carried in a magazine above the camera, while the exposed plates are shifted in a horizontal direction to one side and fall thence to a receiving magazine.
Fig. 50.—American model, English “L” type semi-automatic camera.
