Get your focus and then place disc in hood of lens, straight edge perpendicular (Fig. 98). Cover lens with cap or shutter; insert plate-holder and draw slide; pose your figure directly in front of uncovered portion of lens; expose. Next, without touching disc, slide, or anything but the hood, gently revolve the hood on its threads one-half turn (Fig. 99), and pose your figure on opposite side; expose. The trick's accomplished.
FIG. 98. and FIG 99.
Another arrangement devised by Mr. Frank A. Gilmore, of Auburn, R. I., is shown in Fig. 100.
A black-lined box is fitted to the front of a camera. The front of the box is closed by two doors. On opening one door a picture may be taken on one side of the plate; on closing this door and opening the other, the other half of the plate is ready for exposure.
FIG. 100.—CAMERA FITTED WITH ARRANGEMENT FOR DUPLEX PHOTOGRAPHY.
The subject poses in one position and is photographed with one door open, care being taken to bring the figure within the proper area of the negative. The finder enables this detail to be attended to. Then the door is closed, the other is opened and the second exposure for the other half of the plate is made with the subject in the other position. It is not necessary to touch the plate-holder between the exposures. The cover is withdrawn, the one door is opened and the shutter is sprung. The doors are then changed and the shutter is sprung a second time. Time exposures are rather risky, as involving danger of shaking. A picture made by Mr. Gilmore will be found on the next page.