284 THREE-DIMENSIONAL PHOTOGRAPHY
the projector shutter and gave an excellent stereo result, but
were never used because the spectator would not cooperate by
using the viewer. In fact, the list goes right back to the original
red-green anaglyph, also a somewhat successful method, but one
involving spectator cooperation.
Stereo movies, according to the producers, will never be com-
mercially successful until some method is devised whereby the
spectator cannot possibly see anything other than true stereo re-
lief and without aid of any viewing device. Thus, when we dis-
cuss the failure of stereoscopic motion pictures, let us lay the blame
where it belongs-not upon stereo, not upon the methods used,
but upon the non-cooperation of the spectator. However it is our
belief that the widespread and successful use of stereo still pro-
jection which we now enjoy may change the professional attitude.
Both the dual projection by polarized light and the Vecto-
graphic methods are available, although the latter is hardly prac-
tical for the amateur. The production of long lengths of motion-
picture films in Vectographic relation would require the use of
elaborate production machinery, but this machinery is available,
as it has been used in printing two-color natural color films.
For the amateur, the polarized and non-polarized methods are
both available, and with but slight alteration in the projector, the
successive type is also readily available.
This alternate method was introduced in 1928 for amateur mo-
tion-picture use. Through a curious combination of circum-
stances, a most unusual result was achieved. This was partly due
to the fact that the inventor was not at all familiar with stereo-
scopic principles.
The films were made by two cameras, spaced 65mm and oper'-
ated in synchronism. Thus the right and left images had no
difference due to motion, which produces much better quality
than when the films are made in succession. The positives were
designed for the color anaglyphic method, and the inventor,
through confusion, assumed the cameras must be equipped with
complementary filters. The result was a pair of negatives repre-
senting two-color separations.
The films were printed in skip printers, which advanced the
positive two frames to each single frame of the negative. This left
room for printing the other negative in the alternate spaces. The