STEREO PROJECTION 183
being a motion picture as to object to this cessation of another
form of motion in a still photograph!
EXCESSIVE RELIEF.-Here we must distinguish between that ex-
cessive relief which is caused by a too great screen distance, and
that non-existent excess which is seen at the ortho distance and
which is really only another example of the fact that we do not
know what we see in real life!
TRUE EXCESSIVE RELIEF.-AS we have explained, if the distance
of the spectator is more than the ortho distance, there will be an
exaggeration of relief caused by the diminishing screen size. But
here we encounter the factor of latitude. Consider for example the
35mm lenses of the Realist camera and the approximate 50mm
focal length of the viewer lenses. Here we have the viewing condi-
tions almost 50 percent in excess of the taking. Yet comparatively
few people object to excessive relief of slides seen in the stereo-
scope. The screen picture seen from a distance 50 percent greater
than normal (50 inch picture at about 1 I feet) shows just the same
degree of exaggeration as does the viewer.
The fact is that with the 50 inch picture, spectators seated at
distances from seven-12 feet will not see any depth distortion
which they should not find acceptable in the hand viewer! At
greater distances the relief does increase, but the relief per se
does not become objectionable until the actual distortion reaches
at least 100 percent.
There is no inherent exaggeration which does not aflect all dis-
tances alike. Just as soon as you hear someone complain that
nearby objects have exaggerated depth you know he is speaking,
not of inherent exaggeration but of his own deficient vision! That
defect lies in the continued bond between focus (accommodation)
and convergence of the eyes.
FALSE EXCESSIVE RELIEF.-This brings us to the second part of
this subject, the imagined distortion, for while it is seen by most
beginners it really is subjective, just as is the so-called abnormal
motion of the image.
The whole difficulty with the closeup and its depth exaggeration
lies in the fact that we do not know what we actually see in real
life! If you want to see some exaggerated depth in real life, where
of course it cannot exist because real life is our standard of com-
parison, try this experiment.
frankie
(Frankie)
#1