TRICK WORK 225correctly adjusted you will have a perfect stereogram of the model
playing bridge with herself.
The duplication trick requires more care than the usual double
exposure, and is rarely used except when it is desired to show a
person twice in the same stereogram. The result is so obviously
impossible that it always arouses great interest.
A variation consists of making the first exposure as usual. Then
reverse the masks, making a halftime exposure without the model
and a second halftime exposure with the model to show the model
playing bridge with her own ghost.
It will be seen that double exposure involves (A) exposing the
same film area twice, as in the ghost effects or it may involve (B)
exposing two different areas of the film in sequence. The latter
requires a considerable amount of care in matching the edges of
the two areas, and both demand a rigid tripod to support the
camera immovably during the two exposures.
There are times when two casual, freehand exposures may be
made upon the same film. One of these which we saw showed an
attractive girl seated within a showcase in front of a shop, but
because of the confusion of backgrounds this type of work de-
mands the greatest care of all in selecting the setting for both
exposures and hence is the most difficult.
There is no limit to the possibilities of double and even mul-
tiple exposure, but you must expect disappointments at first. You
must learn the limitations as well as the possibilities, but once you
get past this preliminary obstacle you can have a lot of fun with
the process.
The fact has been mentioned that size differences are faithfully
reproduced in stereo, so that the well-known shot of a girl seated
in a wineglass, so familiar in planar photography, cannot be ac-
complished by the methods which have been described. However
such shots are easy in stereo, but as they involve the fundamental
problem of space control we shall discuss it later in this chapter.
CAMERA ANGLES.-unUSUal camera angles have been worked to
death by the planar photographer, but when used in stereo the
results are so novel that the phrase “angle shot” takes on a wholly
new meaning.
To make this fully clear, one or two related factors must be
explained.