To project thicker objects (up to 1 1/2 inches thick),
lower the platen assembly to the locked position and
remove the roll feed assembly by lifting it off. Place the
opaque object upon the platen assembly, and let it rise
slowly as far as it will go. Apply a continuous pressure
downward on the platen handle with your hand to
prevent the platen assembly from snapping upward
when you release the lock.
Although thick objects can be projected, only one
plane of the object can be brought into focus at a time.
Other planes can be brought into focus when you rotate
the focusing knob. However, when an object is not too
thick, good definition can be obtained over its entire
thickness.
When you use this projector, place it on a table high
enough to project the image over the heads of the
audience. Do not use a low table that requires the
excessive extension of the elevating legs. This produces
a distorted screen image that is impossible to focus
sharply.
There are several disadvantages of using the opaque
projector. It is expensive, relatively heavy (you usually
need more than one person to carry it) and the fan blower
can be noisy when the unit is in operation. Additionally,
the opaque projector does not illuminate the screen as
brightly as other types of projectors. For satisfactory
projection, use a darkened room.
Overhead Transparency Projector
This projector (fig. 6-6) is popular with both
speakers and audiences. You can draw your audience
into your presentation by underlining or writing on the
transparency film as you speak. When you note
audience comments or opinions on the transparency,
they become part of your presentation.
Figure 6-6.-Various types of overhead transparency projectors.
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