Christie DLV1280 DX User Manual page 7

INSTALLATION AND SETUP
Screen Size
Screen Aspect Ratio
2-4
DLV1280 DX User's Manual
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.
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Screen size may be from 5 to 40 feet diagonal, depending on lens you are using. For
instance, a 1.2:1 lens can produce a 5 to 30 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—for this projector, it is likely the standard 1.2:1 lens.
Keep in mind that if the projector will be displaying much text information, the
image size must allow the viewer to recognize all text clearly. The eye usually sees a
letter 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 (or 1.33:1) aspect ratio. For
example, to display a VCR output with a 4:3 aspect ratio onto a 10 foot (3m) high
screen, the width of the screen must be at least 13.3 feet (4m).
Note: Screen size is often specified as diagonal size. Traditionally, screens specified
by diagonal size have aspect ratios of 4:3. Screens with other aspect ratios (such as
those recommended for this projector) are not typically specified by diagonal size.
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Aspect ratio describes the
proportion of the screen or
image, and is expressed as
the ratio of width to
height—such as "4:3" or
"5:4" (see right). Although
image size and image
aspect ratio can both be
adjusted quickly through
projector software, it is still
a good idea to choose a
screen aspect ratio which is most appropriate for your intended applications. Ideally,
to exactly fill a screen with an image, the aspect ratio of the screen should be the
same as the aspect ratio of the image, which can depend on the source in use. For
example, standard video from a VCR has a 4:3 ratio (approximately), whereas a high
resolution graphics signal typically has a 5:4 aspect ratio. By default,
images will be as large as possible and, with the exception of graphics sources, will
maintain their aspect ratio.
Note that with a few exceptions, sources with less than 1280 x 1024 resolution have a
4:3 aspect ratio. The normal aspect ratio for 1280 x 1024 sources is 5:4.
Figure 2.2. Aspect Ratios of 4:3 and 5:4
DLV1280 DX