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While there are two basic screen types, flat and curved, generally flat screens are
recommended for this projector. Flat screens offer a gain of about 1 with a viewing
angle just less than 180°. Incident light reflects equally in all directions so the
audience can see the display from various angles. Because of the low gain, flat
screens are most effective when ambient lighting is reduced, although this difference
may be negligible given the high brightness output from this projector.
NOTE: Lenses for this projector are designed primarily for use with flat screens, but
the projector depth-of-field range allows the lens to be focused on curved screens as
well. While focus remains sharp in the corners, there may be significant pincushion
distortion, primarily at the top of the screen.
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There are two basic types of rear screens: diffused and optical. A diffused screen has
a surface which spreads the light striking it. Purely diffused screens have a gain of
less than 1. The main advantage of the diffused screen is its wide viewing angle,
similar to that of a flat screen for front screen projection. Optical screens take light
from the projector and redirect it to increase the light intensity at the front of the
screen. This reduces it in other areas. A viewing cone, similar to that of a curved
front screen installation, is created.
To summarize, optical screens are better suited for brightly lit rooms where the
audience is situated within the viewing cone. Diffused screens may be better suited
when a wide viewing angle is required but there is low ambient room lighting.
Screen size may be from 5 to 40 feet diagonal, depending on the lens you are using.
For instance, a 1.2:1 lens can produce a 5 to 25 foot image size, whereas a 4-7:1
zoom lens produces an 8 to 40 foot image size. Choose a screen size which is
appropriate for your lens and application. Keep in mind that if the projector will be
used to display text information, the image size must allow the audience to recognize
all text clearly. The eye usually recognizes text clearly if eye-to-text distance is less
than 150 times the height of the letter. Small text located too far from the eye may be
illegible at a distance no matter how sharply and clearly it is displayed.
To fill a screen with an image, the aspect ratio of the screen should be equal to the
aspect ratio of the image. The aspect ratio of an image is expressed as the ratio of its
width to its height. Standard video from a VCR has a 4:3 aspect ratio. For example,
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