Three-Dimensional Photography - Principles of Stereoscopy

x INTRODUCTION

ject. In short, it does not reproduce more than a fraction of the
essential visual detail of any object.
When the stereoscopic photograph is a motion picture in color
and with sound, the picture will often deceive the spectator as
to its reality. One inherent factor of true stereo, or “orthostereo”
as it is called, is that all objects, regardless of the size of the
“print,” are reproduced in their full natural size and at their full
natural distance. Only those who have enjoyed looking at some
well-made stereograms can appreciate the startling realism of
these easily made photographs.
Any camera may be used for making stereographic negatives;
and a simple viewer may be made at home in a few moments by
using two inexpensive magnifying lenses. The negatives involve
nothing more than making two of them instead of one. That is
the sum and substance of elementary stereography. A great deal
of very beautiful and costly apparatus has been produced for
stereographic purposes, but it is not actually essential. These
things, both simple and elaborate, will be discussed each in its
proper place.
While a poor photographic print may pass muster, the poor
stereogram had better not be exhibited. The first requisite is that
the stereographer have the ability to make a really good photo-
graph. More than this, the fundamental aspects of stereography
comprise:

1. Two negatives are made of the same scene but from slightly
   separated points of view.


2. Thepositives must be transposed, exchanging the right and
   the left print.


3. The dual print or stereogram is produced by mounting
   these two prints so that their bases as determined by the camera,
   shall lie in a common line.
   It is possible to make the two exposures freehand, but because
   the positives must later be aligned according to the relative lens
   positions during the two exposures, this method is one for emer-
   gency only. The beginner will find it advisable to provide a
   tripod with some kind of top which limits the scope and direction
   of the camera movement. These may be obtained in elaborate
   form, or you can make a simple sliding base in a few moments
   from a board and three strips of wood. You will find herein in-