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To summarize, optical screens are better suited for brightly lit rooms where the
audience is situated within the viewing cone. Diffused screens are best suited
when a wide viewing angle is required but there is low ambient room lighting.
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Screen size may be from 6 to 40 feet diagonal, depending on the lens you are
using. For instance, a 1:1 lens produces a 6-30 foot image size, whereas a 4-7:1
zoom lens produces a 10-40 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. 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. Screens specified by
diagonal size have aspect ratios of 4:3. Screens with other aspect ratios are not
typically specified by diagonal size.
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The high brightness output of Vista
locations where ambient lighting is less than optimum for projection, but there
are still many simple things you can do to optimize your installation.
Visiting a movie theater can give you an idea of what makes an ideal projection
environment. Walls, floors and furnishings are dark and matte finished. A
projection room should not have white reflective ceilings or non-directional
lighting such as fluorescent lights. The white ceiling spreads light, making the
room appear brighter. Keep lighting and reflections to a minimum.
If it is not possible to eliminate fluorescent lights, consider using incandescent
spot lighting or parabolic reflectors ("egg crates") to direct light down to the
floor. Light dimmers or rheostats allow further control.
Outside windows are undesirable in any projection room. A small crack between
curtains on a sunny day can wash out a projected image. If you do have
windows, make sure that window coverings are opaque and overlapping — some
window coverings are designed to provide up to 100 percent blockage of outside
light. Ideally, the material should have a matte finish.
To minimize the effects caused by unwanted light from door and aisle ways,
carefully choose the position of your projector and screen. Figure 2-6 shows an
installation where poor screen placement allows too much unwanted light to
enter the screen. In Figure 2-7, the screen and the projector are positioned so that
unwanted light is minimized.
10K is certainly well suited for
GRAPHX
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