12. Placement of Projector
Because the reflective qualities of opaque copy is poor, it is difficult
to obtain brilliant screen images from an opaque projector. It is not
necessary for the room to be absolutely dark, but it is important that
the room be made as dark as possible and that the screen be shielded
from direct light, particularly sunlight. If the room cannot be ade-
quately darkened, then the screen image should be kept as small as
practical; this will increase the intensity of illumination on the screen
The size of the image on the screen should be suited to the distance
from which it is viewed. The relationship should be such that the
entire screen can be seen without moving the eyes excessively from
side to side. The use of a large screen image and short viewing distance
is bad practice and results in eye fatigue.
a. Set the projector on a suitable table, at the required projection
distance, with the front of the projector facing the screen. The exact
placement of the projector and the screen depends on the following:
(2) Height of screen.
(3) Height of projector from floor.
(4) Best viewing angle for audience.
b. Adjust the position of the screen so that viewing will not be
obstructed by either the operator or the projector.
13. Operation
When the projector has been set up as desired, proceed as follows:
a. Remove the lens cap, and throw the ON-OFF switch to the ON
position.
b. Place a piece of opaque copy on the projection stage, raise the
undercarriage assembly, and move the projector to left or right until
the image is laterally centered on the screen. Turn the focusing knob
until the image on the screen is in focus, and then loosen the two
elevating rod knurled clamping screws located on the front of the
housing. The elevating rods are spring loaded so that the projector
will be raised automatically to its most elevated position. Adjust the
projector downward until the screen image is vertically centered on
the projection screen; tighten the clamping screws. Now turn the
focusing knob again until the image is brought into sharp focus.
Note. As the line of projection is raised above a horizontal position, the picture
becomes wider at the top than at the bottom. This {Distortion (keystoning) is not
ordinarily objectionable, but it may be corrected by using a screen that can be
tilted forward at the top.
d. When the presentation has been completed, throw the ON-OFF
switch to the OFF position. Replace the lens cap.
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