STEREOGRAPHIC TECHNIQUE 93Filters are quite as important as in planar-monochrome work,
but this subject is discussed in detail in a later chapter.
Choice and arrangement of the subject is a matter of pictorial
treatment and will be discussed later.
The stereo camera differs from the conventional in being two
cameras joined side-by-side, and the actual manipulation of the
camera must take this into consideration. Because the camera
lenses have the relationship which characterizes the two eyes, it is
desirable that this relationship be maintained. Thus if you stand
upon a hillside, your feet, ankles and legs are so positioned that
the body is maintained in a vertical position, and your eyes are
maintained in a common, horizontal axis. When you use the
stereo camera, you should take great care to see that the camera is
not tipped up at either end.
It is often said that the stereo camera must be kept perfectly
level. This is far from the truth. You can tip it up or point it
down with far greater freedom than the planar camera because
the stereo camera realistically retains the vertical perspective of
nature. In the field of drawing, we have only that perspective
which applies to the horizontal. Our world is relatively flat, so the
need of vertical perspective has not been felt until recently. As
a result, a picture of a tall building, made with a conventional
camera, violates our training (although it is perfectly normal, be-
cause perspective does act vertically as well as horizontally). We
say the building appears to be “falling over backward.” In the
stereogram the building has a normal appearance, and if the head
is tipped upward in viewing such a stereogram, the realism be-
comes astonishing.
It would be well, perhaps, to digress a moment and explain that
the cooperation of the spectator can add tremendously to the
effectiveness of stereo. If the spectator does not wish to cooperate,
he is not interested and the loss is his own. This is true of many
phases of stereo, and forms a significant part of technique. Do not
waste time trying to convince anyone who is not interested or who
wishes to argue the question. Stereo is for enjoyment, and if any-
one prefers to indulge in other forms of pleasure, surely the choice
is his. But those who really do enjoy stereo find they can increase
viewing pleasure by just such “orientation” aids as bending for-
ward to view stereograms made with the downward pointing cam-