Madrigal Imaging MP-9 - Manual (Page 11)

Screen Size and
➤
Throw Distance
Screen size and throw distance are interrelated. (See Appendices F and G.)
As screen size increases, the distance between the projector and the screen
also increases. During projection room design, make sure that the room
can accommodate the required position of the projector for the screen size
you need.
Screen Size
Screen sizes vary according to model and lens type. (See Appendices F
and G.) Choose a screen size which is appropriate for your application. If
the projector will be used to display text information it is important that
the image size allows the audience to clearly resolve all text. 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 not be legible at a
distance even though it is projected sharply and clearly on the screen.
To fill a screen with an image, the aspect ratio of the screen must be equal
to the aspect ratio of the image. The aspect ratio of an image is 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.
Throw Distance
The throw distance (projector-to-screen distance) must be determined for
every new installation. Throw distance, the distance between the projector’s
center lens and the center of the screen, is based on screen size. As screen
size increases, the distance between the projector and the screen increases.
Make sure that the room can accommodate the required position of the
projector for the chosen screen size.
Once your screen size is known you can determine the required throw dis-
tance for your projector model and lens by using the formulas in Appendix
G and tables in Appendix F.
Notes: 1) Calculated values are for reference only. It is good practice to simulate
the setup to determine the necessary throw distance. 2) Display size is affected by
input signal characteristics. Once the projector is set, use the Size function to fine
tune display size.
Throw distance and projection angle: Keep in mind that the ability to
properly focus all areas of the image is limited if a significantly tilted
projector is too close to the screen.
INSTALLATION & SETUP
2.5