This section is from the book "Modern Photography In Theory And Practice", by By Henry G. Abbott. Also available from Amazon: Modern photography in theory and practice: A hand book for the amateur.
Stereoscopic photography does not seem to be popular with amateurs although it is the most perfect manner in which a scene can be reproduced. It has doubtless been unpopular solely on account of the extra work involved. As a rule the amateur is looking for good results by the shortest methods. It is hardly necessary here to explain the theory of stereoscopic photography but suffice it to say, that comparatively speaking, an ordinary photograph is flat and wanting in detail when compared with an equally good stereoscopic view. The latter view gives a roundness and natural effect to all the objects in the scene and particularly those objects in the immediate foreground. This characteristic is what makes the stereoscopic picture the very closest thing to nature. The rocks, the grass, the trees, all stand out boldly as they do when viewed in nature. Scenes and objects with minute detail, which would be entirely lost in an ordinary photograph, are the very choicest subjects for stereoscopic views. Snow scenes, apple and cherry trees in full bloom and similar subjects in which the close detail is lost on printing paper, show their full beauty under the stereoscope.
Stereoscopic cameras are built by many of the leading manufacturers but are usually intended for tripod use.
The Vive Stereoscopic Camera, which is shown in Fig. 38 is applicable either for hand or tripod use. This camera takes two pictures of the same scene, 3(1/4)x 3(1/4) inches on the same plate at one exposure. The camera is fitted to use either cut films or glass plates and the size of the plate is 3 1/2 X 6 1/2 If desired each lens can be worked separately, so that two entirely different subjects can be taken on the same plate.
In all stereoscopic cameras the two lenses are of course matched and they are usually about three inches apart, from center to center, this being the distance that the average eyes are apart. The lenses might be as near as two and a half or as far apart as four inches and still produce stereoscopic pictures but much depends on the lenses. Stereoscopic pictures may also be taken with ordinary hand cameras by constructing a very simple mechanism but the scenes must be limited to still life Any amateur who is handy with carpenter's tools can make the attachment or your carpenter will make it for you for a small sum. To start with let us assume that you have a box camera whose base is say 5 1/2 x 7 1/2 in. Select a piece of well-seasoned white wood, pine or cherry lumber, a half inch thick and 5 1/2 x 7 1/2 inches in dimensions.' This will act as the base for the camera. A hole which will just take the camera screw is bored in the exact center and a small frame whose outside dimensions are 4 x 6 inches is nailed in the center, so as to leave a 3/4 inch margin all around. You now have a piece similar to that shown in Fig. 39. The frame may be either mitered or square as taste dictates. Now select another piece of board 5 1/2 x 10 1/2 inches and nail to this a frame of the same dimensions made of 3/4 inch square stuff and you will have a piece similar to Fig. 40. Bore a hole in this and in this hole insert a tripod screw nut, the same as is fitted in the bottom of your camera. An extra tripod screw will have to be purchased for use in the piece shown at Fig. 39. The piece shown at Fig. 40 is now fastened by means of the tripod screw to the head of the tripod, where the camera usually rests. The smaller piece or slide, shown in Fig. 39 is fastened to the bottom of the camera by means of the extra tripod screw, the smooth side of the board to the bottom of the camera. When the slide is placed on top of the large base board it presents an appearance similar to Fig. 41. It can be shifted back and forth, from right to left, just three inches, the frame on the small sliding piece acting as a stop at both ends and as guides at the side.
It is quite evident that if we screw the camera to the top slide, move it over to the right and expose a plate, then move it three inches to the left and immediately expose another, that the result will be two negatives, similar to those produced by a stereoscopic camera, except that in the latter the two views are on one plate. Care will have to be exercised to either mark the plate holders "right" and "left" or to keep a record of them, for it is absolutely necessary to know which is which when we come to mount the prints as will be explained later. In taking views for stereoscopic purposes with a single lens camera there are several points which will have to be guarded carefully. Motion of all kinds will have to be excluded; moving figures, leaves, etc. This is not the case with the regular stereoscopic camera for with it we can take snap shots or time exposures. Again with the single lens we must carefully watch the light and give exact exposures to both plates or the result will be an imperfect picture. Should a cloud pass over the sun after we have taken the first picture we will have to wait until the sun comes out again or the negatives would not be mates.
The exposure for stereoscopic negatives is done as with ordinary scenes except that a little over rather than a little under-exposure is better. The development should be carried on as with ordinary exposures. Any ordinary printing out paper will make good stereoscopic views but silver paper and collodion and gelatine papers produce better results than bromides and platinotypes. A smooth paper with a brownish tone will give better results than a rougher paper or a blacker tone. Brilliant prints are not a necessity and in fact are a detriment, for when viewed through the stereoscope they look fuzzy and glaring instead of soft. In printing from a regular stereoscopic camera negative, a special printing frame is necessary, as the plate is longer and narrower than the average, or a large printing frame may be used with a plain glass in it and the stereo-negative placed on the plain glass. When printing from two negatives made from a single lens it will be found desirable also to use a large frame with plain glass, so that both negatives may be printed at the same time and the color kept uniform thereby. The prints should be numbered and marked on the back with a lead pencil so that they can be sorted out in pairs after toning and washing, otherwise you will get into trouble. After printing mark the backs 1-R, 1-L, 2-R, 2-L, etc. and you will have no trouble in sorting them out.