196 THREE-DIMENSIONAL PHOTOGRAPHYJust so the stereo projector is basically what it has been for sev-
enty-five years. It can be dressed up, more efficient lighting and
cooling may come, automatic changers will come and improve-
ments of that kind, but the basic principle will remain as it is for
a long time. This is because, just as electricity and steam as power
for the automobile were discarded, so in stereo we have tried and
discarded the flicker system and the two-color system for the ob-
literation of the unwanted picture.
There is nothing wrong with the present basic technique. It is
based upon sound stereo principles and the faults of stereo pro-
jection today are inherent faults, if you wish to call them that, in
that their origin lies in the underdeveloped visual skill of the spec-
tator, not in the projection equipment or method. Therefore,
while projectors will undoubtedly be improved, for many years
those improvements will undoubtedly lie in the improvement of
the details of the present system.
THE GOGGLE QuEsTIoN.-Some people object to wearing the
viewing goggles, although why this should be true it is impossible
to understand. When you drive in the sun it is most comfortable
to have a pair of goggles to put on. No one objects then although
they are simply a convenience, not a necessity. Frankly the men-
tality which would forego the great pleasure of stereo viewing
because of the necessity for wearing a pair of extremely light
weight goggles is beyond the writer’s comprehension.
It is perfectly true that we do have “free vision” projection, that
is projected stereo which does not require goggles. The method
depends upon filling a certain space, such as an auditorium, with
pairs of light beams, one right and one left. Then provided the
spectator will wiggle his head around until he finds the correct po-
sition, and provided he will keep his head in just that exact
position for the duration of the exhibition, he will see true stereo
without the use of any kind of viewing goggle, but the price is too
high to pay.
- When the space is filled with these beams, it is just as easy to
find a position with reversed stereo as to find the right one. - These beams must necessarily diverge, so at the rear of the
room the spacing will be too wide for normal vision and a flat
picture will be seen. - If a blanking space is used to prevent the effect of (I), then