This section is from the book "Complete Self-Instructing Library Of Practical Photography", by J. B. Schriever. Also available from Amazon: Complete Self-Instructing Library Of Practical Photography.
Selection Of View-Point. The accuracy of the selection of point of view for stereoscopic work is even more important than for regular view photography. The stereoscopic picture to be interesting must have objects in the immediate foreground, to give a stereoscopic sense of relief or distance, and to lead the eyes into the picture, at the same time breaking up the monotony of plain space.
553. With the regular stereo camera, where the lenses are mounted stationary, the best stereoscopic effects are obtained where the nearest object is not farther away than fifteen feet, and in many cases, especially interior views, small objects within six to ten feet of the camera assist materially in balancing the picture.
Lighting And Exposure. The lighting of all subjects intended to be reproduced and to form stereoscopic pictures should be soft, rather than hard and contrasty. The high-lights must not be so white that they will produce a chalky effect, nor must the shadows be so dense that no detail is obtainable. As a general rule, the most satisfactory pictures for the stereoscope are those which have been taken in a subdued light and a fairly long exposure given the plate. The amount of exposure for different subjects is exactly the same as when using the lens singly.
Development. Stereoscopic exposures are treated in exactly the same manner in development as the ordinary exposure, but you must develop for softness and detail.
When two separate plates are employed for stereoscopic pictures, one must aim to secure perfect uniformity, bearing in mind that a thin negative yields better prints than a dense one. Aim to secure detail in the shadow portions before the high-lights become too dense. A diluted pyro developer or the Universal Developer given in Volume II are best suited for developing stereoscopic negatives.
Printing. In making stereo prints it is necessary to transpose either the negative before printing or the trimmed prints before mounting. The reason for this is, the lens throws an inverted image on the film; therefore, when the negatives are viewed right side up, the one on the right is from the negative made by the left lens. To correct this the negatives or prints must be transposed. This may be done in either of three ways: First, by making one solid print from the negative as it is, then cutting the two prints apart, and finally, transposing before mounting. Second, by cutting the negative in half and, after transposing the two views, mounting them on a piece of plain glass. The edges are fastened with binding tape and the print made on one solid sheet of paper. Third, by means of the stereo self-transposing printing-frame, manufactured by the Blair Camera Company, and made to hold only films. By means of this printing-frame the cutting of the negatives is done away with. The accompanying illustration, No. 112, of this frame is self-explanatory. This frame is made for developing papers only, to be used in connection with film negatives 3 1/4 x 6 1/2, and is not adapted for glass plates, as they come in different thicknesses.