Set up the projector and screen. Be sure the screen surface
is clean and flat. Turn on the projector with a blank mount in it.
(Or better yet use a calibrated projector control slide made for the
purpose). First set the projector screen distance so that the picture
just fills the screen surface.
Adjust the vertical balance so that both films are of exactly
the same height upon the screen. Once this is done do not touch
this adjustment while the spectators can see the screen.
Now set the horizontal so that the correct overlap of pictures
is obtained. (A) Set infinity images at 2% inches, (B) Exactly
superimpose images of objects at seven feet, (C) Register the mask-
openings provided masks with seven foot windows are used. Do
not readjust this setting while spectators can see the screen.
Run through slides as a recheck to see that none are out of
alignment. If any are, set them aside for remounting. DO NOT
TRY TO PRESENT THEM BY USING THE PROJECTOR
POSITIONING CONTROLS.
Focus the projector lenses, watching the image from the fixed
lens. Then focus the adjustable lens to coincide.
Now, and not before, admit the spectators and give the show.
Do not leave a slide on the screen for more than 15 to 20 seconds
at a time. As the usual time for an average slide is five to ten
seconds, this gives you ample time for each slide. Prolonged ex-
posure to light of such intensity will in time affect the color of
the slide. Modern color films are intended for projection and are
highly resistant, but it is wise to keep on the safe side.
Turn up room lights and then turn off projector. Allow it to
cool off before putting it away in the case.
Take down screen and repack it. Do not leave it standing
around because the surface is delicate and a little food or drink
spilled upon it, or a chair arm forced against it and you will need
a new screen fabric.
IF YOU WILL KEEP YOUR HANDS OFF THE POSITION-
ING CONTROLS OF THE PROJECTOR-AND IF YOU
MAKE SURE ALL SLIDES ARE IN ALIGNMENT BEFORE
THE SHOW STARTS, you will not need €ear making anyone ill.
If you have extreme closeups you may cause some strain and
pull in the eyes of spectators unaccustomed to stereo, but this will
