They're the cheapest path to big-screen heaven these days, until projector prices come down. But watch out for the pitfalls.
For a truly big-screen home-theater experience, a front projector is the only way to go. As the name implies, a front projector sits in front of a separate screen much like the setup of a film projector in a movie theater. And similar to the cinema experience, you'll need to turn the lights way down and block the windows to see the picture in all its glory. There are basically three types of front-projection technologies available today: CRT, LCD, and DLP; and each one has its limitations. The oldest and still the reigning champ in picture quality is the cathode-ray-tube-based (CRT) projection TV. Though CRT-based front projectors produce the best picture, especially in terms of the resolution, the black level, and the contrast ratio, the drawback is that the pictures these projectors offer are rarely bright enough. What you may not realise, though, is that screen size becomes an important factor when dealing with CRT-based front-projection TVs.
Blown up and blown out
Most projectors are capable of producing an image on a 15-foot-wide screen, but you don't really want to make your system do that. Once you exceed the optimum screen size of your projector, you have to drive the machine harder just to light up the screen. This has two nasty side effects: first, the tubes will burn out much faster than they would with more reasonably sized screens, and secondly, the picture quality will begin to suffer.
When you crank the contrast control and drive the projector too hard, you introduce geometric distortion (where straight lines begin to curve), and the colour fidelity goes down the drain. The scan lines that make up the picture also become more visible on a very large screen, especially if you're sitting close to it. Properly set up on a reasonably sized screen, CRTs can last up to about 10,000 hours. However, if you severely overdrive the projector to accommodate a larger screen, the tube life will drop by 60 percent or more. For optimum picture quality on CRT-based front projectors, follow these basic guidelines:
- For 7-inch CRT front projectors, the optimum screen size is a 72-inch-wide, 16:9 aspect-ratio screen.
- For 9-inch CRT projectors, the optimum screen size is an 84-inch-wide, 16:9 aspect-ratio screen.
