INSTALLATION & SETUP
Roadie S12/X10 User’s Manual 2-5
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.
Rear Screen Installations
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 (image size) may be from approximately 5 to 50 feet diagonal, depending
on the lens you are using. For instance, a 0.8:1 lens (0.6:1 as SXGA) can produce a 5
to 25 foot image size, whereas a 4-7:1 zoom lens (3.1-5.6:1 as SXGA) produces a 10
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 sees a letter clearly if eye-to-text distance is less than 150 times the
height of the letter. In other words, small text that is simply located too far from the
eye will be illegible no matter how sharply and clearly it is displayed.
NOTES: 1) Screens with aspect ratios of 4:3 are typically specified by diagonal size,
but screens having other aspect ratios are not always specified by diagonal size. 2)
Stated screen sizes below refer to the diagonal size of a 4:3 screen—a 5:4 screen may
differ slightly.
Lens Type Diagonal Screen Size
0.8:1 fixed (NOTE: 0.6:1 as SXGA) 5’ - 25’
1.5 – 2.5:1 zoom (NOTE: 1.2 – 1.9:1 as SXGA) 6’ - 40’
2.5 - 4:1 zoom (NOTE: 2.0 – 3.2:1 as SXGA) 6’ - 40’
4 - 7:1 zoom (NOTE: 3.1:1 – 5.6:1 as SXGA) 10’ - 40’
7 – 15:1 zoom (NOTE: 5.4:1 – 12:1 as SXGA) 10’ – 50’
Aspect ratio describes the
proportion of the screen
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 projector. Ideally, to exactly fill a screen with an
Screen Size '
Screen As
ect Ratio '
Figure 2.6. Aspect Ratios of 4:3 and 5:4
