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.
If you are printing from a single plate made in a stereo-camera you will note that the view taken by the right hand lens is on the left hand side of the plate and vice versa. This being the case you will have to cut the views apart, after toning, washing and drying and transpose them, so that the view taken by the right hand lens will be opposite the right eye when viewed through the stereoscope and vice versa. The trimming of stereoscopic prints is of prime importance for if they are not properly trimmed and mounted all the effect is lost. Some prominent object as a stump, stone or fence should be selected in the foreground as a guide point and the print trimmed from it. We will suppose in our example that there is a stump in the foreground. In trimming the two prints this stump must be the same distance from the bottom edge of print and the two prints the same size in height. In trimming the sides, however, we take another course. We again take the stump as a base mark and in trimming the right-hand print we allow a quarter of an inch more to show on the left of the stump than shows on the left of the other print and in trimming the two prints to the same size we naturally have a quarter inch more space showing on the right-hand side of the stump than appeared on the right-hand print. This will be made clear after you have trimmed and mounted your first prints and viewed them in the stereoscope or you will perhaps grasp the idea better by examining a ready-made stereo-picture. In mounting, about a quarter of an inch should be left between the two pictures on the card and a dark mount is preferable to a light colored one.
During the last few years considerable attention has been paid to panoramic views by amateurs. These views are usually made by means of the ordinary box camera by shifting it on the tripod from left to right. Two, three and sometimes four exposures are made from the same point by simply turning the camera slightly on the tripod screw. It is important to study the scene before you carefully, so as to determine where the joining shall take place. As a rule, it is better to join at the edge of a building, tall tree, or some such object which cuts well into the sky, as the joining is less liable to be noticed. Starting at the center, the view is carefully focused and if it is intended to make a three-piece panorama, the prominent objects to the right or left are indicated by vertical pencil marks on the ground glass.
The camera is then swung to the left and placed in such a position that the image on the ground glass shows that the tree or prominent object whose location was noted by means of the pencil line on the left of the ground glass, just overlaps that line. The exposure is then made, the camera moved to the center, the next exposure made and then swung to the right. In each instance the subject should lap, say three-eighths of an inch for safety and even a half-inch is better, then in case of any frilling at the edge of the plate you are still safe. A special printing frame, long enough to take a sheet of paper which will cover all three negatives, is procured. Special frames for panoramic printing are now to be had on the market. The backs are arranged to open in three and four compartments. The center negative is placed in position and the balance of the opening in the printing frame is blocked out by means of black cardboard. The sides of the center negative are also blocked out up to the point where you wish the joining. The center is then printed, the center negative removed and the left hand negative placed in position to the left in the printing frme. The right hand side of the negative is now blocked out up to the line where it joins the center one, the balance of the frame blocked with black cardboard and the printing proceeded with. The right hand negative is treated in similar manner and the print is then ready for toning.
All this, of course, means work and for this reason a special camera has been placed on the market, which is known as the "Al-Vista." It is a panoramic camera which makes negatives 4 x 12 inches in size. This camera enables the operator to take in a scope of nearly 180 degrees, or half a circle. The size of the camera is 5 x 5 3/4 x10 1/2 inches and it weighs but a little over 2 lbs. when ready to operate.
Fig. 42 shows a front view of the camera before exposure. You will note that the lens is pointing towards the right as we look at the camera from the front. The exposures are made on a roll film and the film passes from one side of the box to the other, not in a straight line, as in ordinary roll film cameras but in a half circle. The back of the box has a semi-circular groove and the film follows this circle, as you will see by consulting Fig. 43. You will see why, when you understand the action of the camera. When all is ready you start the mechanism and the lens sweeps from right to left, as you view it from the front. In making this sweep the film must necessarily be on a half circle in order that the lens be the same distance from the film at every stage of its turning. When the sweep is completed the lens points to the left, or opposite to where it started, as shown in Fig. 44. When the exposure is made the film is wound up for another exposure, there being an indicator which shows when enough film has been brought into position. The film is perforated by a punch, which shows where it is to be cut off,. then you are ready to develop in the dark room.
The mechanism operating the lens is so constructed that you can change the speed, fast or slow, according to the light. The light coming through the lens does not strike the film in a circle as in other cameras and you can readily see that the angle of the most narrow angle lens would be so wide as to produce a blur on account of a double impression in some places. This is obviated by means of a funnel-shaped tube extending back from the lens about 3 1/2 inches but the end of the funnel is not round but a rectangular slit, which allows only a streak of light to strike the film at one time. Any four-inch daylight loading film may be used in this camera.
Time 1-50 Cloud Effects. Henry G. Abbott