Projection Screen Size Selection - one of the most important decisions to make in selecting the correct screen.
Determine the correct size based upon:
- The dimension of the Audience Area
- The Projection Screen Format(s) to be used.
Other key considerations:
Audience Area —The goal is to make the screen large enough so those in the back row can read the subject matter easily, but not so large as to overwhelm the closest viewer.
- Height—Use the following formulas for calculating screen height for maximum legibility.
- For 4:3 NTSC/PAL moving video and entertainment, screen height should be at least 1/6 the distance from the screen to the furthest seat
- For charts and data, as in a conference or lecture room, use 1/4
- For complex graphics found in a command/control center, use ½.
- For HDTV projection (16:9), Widescreen, 16:10, or 15:9 formats, screen height should equal or exceed 1/3 the distance from the screen to the optimum seat.
- Width—Screen width is generally determined by the height of the screen and the projection formats to be used.
- Ceiling Height—The bottom of the screen should be approximately 40-48" above the floor in a room with a level floor and several rows of seats. In rooms with theatre seating or only one or two rows, the bottom of the screen should usually be 24-36" above the floor. Evaluate any barriers, and try to make sure that the lower part of the screen will be visible from all seats. Extra drop may be required to position the screen at a comfortable viewing level in a room with a high ceiling.
When selecting a front projection surface, several factors need to be considered
- Gain—a relative measure of a screen’s reflectivity.
- Contrast—the ability to accurately reproduce and differentiate light and dark characters and backgrounds, or light and dark areas of an image.
- Ambient light rejection properties—the ability to perform well under normal to adverse audience lighting conditions.
- Resolution—the clarity of the projected image.
- Uniformity—the screen’s performance when viewed from various points off the projection axis (both horizontally and vertically), and when the brightness of the center of the image is compared to the corners.
- Aspect ratio—the screen’s height and width configuration, formatted for the desired projection source (NTSC video, HDTV, WideScreen, CinemaScope, overhead, slide or motion pictures).
Here is a chart in PDF format that shows the gain on the various Draper screen surfaces