DUPLEX PHOTOGRAPHY.
The following very ingenious method is pointed out by M. H. Duc, of Grenoble. It consists in making use of a special frame which, instead of having a sliding shutter, is provided with two shutters that operate like the leaves of a door. These shutters, B B ([Fig. 1]), pivot upon two vertical axes, A A, whose upper extremities project from the frame so that they can be maneuvered from the exterior. As the shutters must join very accurately, M. Duc affixes asbestos paper to their edges. A sliding steel plate, E D, permits of keeping the two shutters closed before and after exposure. This is removed when the frame is in the camera.
FIG. 1.—PLATE FRAME.
The ground glass is divided into two parts by a pencil line that exactly tallies with the junction line of the shutters. The subject is focused on one of the halves of the glass, and then the corresponding side of the frame is unmasked. After exposure the model changes place, and then the other side of the frame is opened.
FIG. 2—COPY OF A PHOTOGRAPH SHOWING
THE SAME PERSON THRICE REPEATED.
The photograph reproduced in [Fig. 2] was taken in this manner. It contains three representations of the same person. The easel, stool, and artist having been arranged, an image is taken on the left side of the plate, then the painter moves his position to the right and a second exposure is made. The portrait on the easel is that of the same person, but was taken afterward on the positive by means of the negative and a vignetter ([Fig. 3]).