Overhead Transparency Projector

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. 6-22