200 THREE-DIMENSIONAL PHOTOGRAPHY
soon pass. Simply warn them that if anyone feels uncomfortable
eyestrain, he should stop looking at the picture.
Stereo projection is fully satisfactory, but like many other hu-
man activities it requires human cooperation. Although the sub-
ject could easily fill a book the size of this one, enough has been
told in this chapter to enable you to cope with all of the usual
home projection problems, but in closing, let me repeat the warn-
ing: DISCOMFORT AND ILLNESS WILL INEVITABLY
RESULT FROM MAKING CONTINUED ADJUSTMENTS
OF POSITIONING CONTROLS WHILE SPECTATORS SEE
THE SCREEN.
I wish those words could be printed in bright red! Many begin-
ners just can’t obey, they think they MUST bring each slide into
exact registration. I told this to a beginner once and he said he
understood thoroughly yet at the fourth slide he reached for the
control! I asked why and he said “Well you can’t let the slide stay
on the screen out of alignment. It won’t hurt to move it just a
little.” What can one do to emphasize the fact that even if some
slides are badly out of alignment, more harm is done by the cor-
rection than by the misalignment?
The warning is meant literally. Simply do NOT EVEN
TOUCH those vertical and horizontal controls, no matter what
happens, DO NOT TOUCH THEM, no, not even with the tip
of one finger. Just act as if they were both red hot. If you can
overcome this alignment itch enough to follow instructions, two
thirds of your projection troubles will disappear and none of your
spectators will ever again become sick.
Just follow your common sense and the instructions which ac-
company your projector and you will be happy. Do not expect
miracles. Give yourself time to become accustomed to stereo pro-
jection; work with the projector, not against it and you too will
become one of the thousands of enthusiastic stereo projectionists
of this country.