How to buy a screen

Evan Powell, March 16, 2000
Contents
Care and Considerations

Maintanence and cleaning. Some screen fabrics can be cleaned with soap and water. Others must be protected from any kind of damage or marks, as any attempt to clean them will impart additional damage to the fabric. So if you are setting your screen up in a business presentation area, you should anticipate that presenters will inadvertently mark the screen surface when they use an uncapped pen as a pointer, or slap the screen with a ruler to make a point. In an environment like this, it is important to choose a screen fabric that can be cleaned easily. On the other hand, if you are using a retractable mount in a home theater setting, the screen will be less susceptible to careless damage, and this may not be as important.

Screen size. Some people say that the ideal viewing distance for home theater screens is 1.5 times the width of the screen. So if you plan to view the screen from a distance of twelve feet, the screen should be eight feet wide. This formula is wrong. Actually, all formulas are wrong. Screen size relative to viewing distance is purely a matter of personal taste, just as some people like to sit in the first row of a movie theater, and others like to sit as far back as possible. Keep in mind, however, that if you are viewing a large screen from a close distance, your eyes will not be able to resolve the entire image at once, and they will be moving around to capture the action. This can be uncomfortable over the two-hour duration of a movie.

Keep in mind that any given projector only has a fixed amount of light. So if you spread that light over a larger area, the picture will look less bright than it will if you focus all of that light on a smaller area. A common mistake that is made is going for the biggest possible screen, and overstretching the ability of the projector to produce an ideal picture. Yet even this is a matter of taste. Some people prefer a bigger image that is a little less bright and lower in contrast. Others will prefer to limit the image size in order to maximize brightness and contrast.

Aspect ratios. All vendors offer screens in a variety of sizes, both in 4:3 and 16:9 aspect ratios. (Aspect ratio is the ratio of the width to the height of the screen. Standard television is 4:3. The new widescreen high definition television format (HDTV) is 16:9. Most movies made today are wider than 16:9) Actually, you can get many fabrics cut to whatever size and custom aspect ratio you want. The question is-which is right for your set up?

This aspect ratio issue warrants some attention. First, let's focus on this fact: almost all LCD and DLP projectors have a native 4:3 aspect ratio (that is, 4:3 is the aspect ratio of the LCD panels or the DLP chips that are inside the projector itself). The current exceptions are (a) the unique Sony VPL-VW10HT, which has native 16:9 LCD panels, and (b) most SXGA resolution projectors, which are native 5:4 (1280 x 1024).

Now if you have a projector that has a native 4:3 display, in order to get the maximum light output and maximum resolution of your projector onto the screen, the image being projected must be 4:3. This is entirely contrary to the logic that the HDTV 16:9 widescreen format will produce the best image quality. But the fact is that when you display a 16:9 image using a native 4:3 projector, you are not using the total pixel array and light output of the projector. Part of the display is masked to achieve the 16:9 format. This produces the horizontal black bars on a 4:3 screen that we are all familiar with. But the width of the image is usually the same in both formats. (For exceptions to this rule, see note below.)

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