December 2006 - HowTo - Shop For A Front-Projection HDTV - page 2
Choosing the Screen
 There’s no law mandating the use of a screen with your projector. If you only bust out the system for the occasional movie night, it’s okay to simply throw the image against a white or gray wall, provided said wall is smooth and blemish-free. But a good screen can make a world of difference, especially if you choose a screen material that perfectly complements your projector and your viewing environment. I could devote an entire article to screen material but, for the purposes of this how-to, let’s focus briefly on the two principal specs that affect screen performance: color and gain. The color of screen you select, usually white or some shade of gray, is dictated by your viewing environment. White has long been the standard for home theater screens, because it’s generally the best choice for a dedicated theater room that has complete light control. A gray screen, on the other hand, will absorb (rather than reflect) ambient light, which makes it a better fit for a family room or other environment where you might watch videos with some lights on. Some dealers will get you different screen materials to try, and any trained calibrator can measure the effect of different screen materials in your theater.
Gain is also a measurement of reflectivity, but it deals more specifically with the relationship between the screen material and the light coming directly from the projector. A 1.0-gain screen reflects the same amount of light as a white magnesium oxide board. A 1.5-gain screen would reflect 50 percent more light, while a 0.5-gain screen would reflect 50 percent less. Most home theater screens have a lower gain, between 1.0 and 1.5; this strikes a good balance between reflectivity and even dispersion of light around the screen. Stewart’s GreyHawk is a negative-gain screen (0.8 gain) designed to help improve black level by reflecting less light from the projector. Several manufacturers have introduced high-gain screens designed for use in a brighter room; these screens reflect more of the projector’s light to make the image seem brighter. While performance varies between models, every high-gain screen I’ve seen has struggled with the ability to distribute light evenly around the screen. The image will be very bright in the center but will get duller as you move to the screen’s edges. Finally, if you plan to hide your front and/or center speakers behind the screen, make sure you select an acoustically transparent material that allows the sound to pass through it without much degradation.
 Once you’ve chosen a screen material, you need to decide how you want to install the screen in your theater space. Do you want a fixed screen that’s permanently mounted to the wall, or is your entertainment space in a constant state of flux, mandating something more movable? Do you want a screen that’s always visible or one that magically appears at the press of a button? The budget-conscious shopper may opt for a simple pull-down or pull-up screen. Just mount the screen to a wall, ceiling, floor or tripod, and manually extend it when you want to use it. The next step up is the fixed-frame screen; as the name suggests, the screen comes mounted in a fixed frame that you hang on the wall like a picture frame. If you like the idea of the hidden screen but want something a tad sexier than the manual pull-down type, you can go for the motorized screen, which automatically lowers from a long, thin, wall- or ceiling-mounted case. All three of these options generally allow for only one screen shape to accommodate the many aspect ratios you may encounter: 1.33:1, 1.78:1, 1.85:1, 2.35:1, etc. If you just can’t abide the sight of unused screen space, consider an automatic masking system that extends drapes or other masks to perfectly frame whatever shape content you’re watching. Needless to say, this will run you a few extra dollars, but can be well worth it for its coolness factor.
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