FIG. 106.—MOUNTINGS FOR TRIPLICATORS.

While doubles are well known to many amateurs, the making of three exposures of one subject on a single plate is not so common. Mr. Chas. A. Barnard has furnished particulars of his method of making the pictures shown in Figs. 107 and 108. Fig. 106 shows two methods of mounting the attachment in front of the camera lens, one being designed to slip over, while the other screws into the lens barrel, the front of which is often fitted with a screw thread. Fig. 109 shows the stops which slide in this mounting; in making them, first mark on each the position of the center of the lens by measuring up from the stud which holds the stop in place. Draw your circles for stops with this as a centre, and as large as diameter of lens. Leaf A is used for the sides of the triplicator, reversing between the exposures. With an inch circle, the width of this is 0.2 inch. The edges should be filed down as thin as possible without nicking. Leaf B is for the centre exposure of the triplicator, and the slot is 0.012 inch wide and 1 inch long. Leaf C is the duplicator stop, its width being 0.3 inch. Leaves D1 and D2 are for top and bottom exposures of a vertical double, and are the same size as C. The proportions might have to be slightly varied for some other lens, in all these cases. A triplicate exposure is made as follows. First focus, using the whole lens, at any stop, and determine the limits of your picture spaces. As the leeway is small, do not get the figures too large. Pose the model in the centre, stop down till properly lighted, and note the stop and mark edges of view on ground glass. Focus on model at one side, stop down till edge blends into edge of previous view, and note stop. Do the same in third position. This may take some time, and a chair may be used instead of a model. Finally, put in the plate and make the three exposures, giving four times the exposures ordinarily required for the same stops. The order is immaterial. Stops recommended for a 3-1/4 × 5-1/2 camera are as follows: For a horizontal doublet, leaf C, U. S. 16; for a vertical doublet, leaf D1, U. S. 54, leaf D2, U. S. 40; for a horizontal triplet, leaf A, U. S. 16, leaf B, U. S. 90; for a vertical triplet (leaves not shown in drawing), leaf A for top, U. S. 32; for bottom, U. S. 20, leaf B, U. S. 90. Vertical pictures are extremely difficult to figure.