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A movie screen isn't always the first item on a home-theater shopping list. How many of us have been tempted to feature the grand premiere of our first front projector on the largest wall in the house? Somehow, that initial impromptu screening leads to a second, and so on. In the videophile world, this is the equivalent of buying a new Ferrari and taking the inaugural run with the cheapest set of tractor tires you can find. If the next time you watch a movie, you see that the star's face has a bit of a drywall texture to it, you might want to consider retrofitting your theater with a projection screen.

One of my favorite retrofit jobs as a custom installer involved a location that already had a 40-seat theater and a 24 x 30-foot projection room — with about 30 large sheets of vellum drafting paper (pieced together with Scotch tape) covering the 16 x 9-foot hole between the two rooms. For 2 years, a small $1,000 business projector had been sitting on a chair in the projection room, beaming images onto the back of the paper. After my initial meeting with the client — when he asked if we could help the image look a little better (I still can't believe I was able to keep a straight face) — I suggested a "minor" projector upgrade to an InFocus SP777 (about $30,000 at the time; currently, it retails for $9,999), and I also recommended using a Draper 16 x 9-foot rear-projection screen to service his 40-seat palace. Since his experience with projectors was limited to the local big-box office-supply store, he thought we were miracle workers when he saw the resulting image.

With that cautionary tale in mind, let's take a look at all the things you need to consider before buying your first screen or upgrading your current one.

Gain and Diffusion In Action

Click the image to see Gain and Diffusion in Action

Gray vs. White

The question of screen color is one of the most common, especially since gray models are often called "high-definition" screens. White screens are the standard in the local movie theater, so why should you use gray at home? The answer lies in the technology (or lack thereof) in the early digital projectors, which suffered from very low contrast ratios. Gray screens help address that problem by giving the projected image the illusion of higher contrast.

So the next logical question is: Are gray screens obsolete with today's high-contrast projectors? Surprisingly, no. Gray screens are useful in any environment where you don't have total control over the light. Most projection screens today are being installed in multi-use settings such as media rooms, which often have some ambient light as well as reflected brightness from light-colored furnishings. These reflective surfaces cause stray light to shine back onto the screen, reducing the picture quality. A gray screen can help offset the impact of these reflections. In a true dedicated home theater where the light is fully controlled and the room contains dark furnishings and low-reflection materials, however, the combination of a high-contrast projector and a white screen is the way to go.

Gain and Diffusion

Gain is a measure of how well a screen material reflects light, while diffusion is a measure of the light-scattering across a viewing area. Gain is determined against a white (magnesium oxide) board reference, and it's measured from the point where a screen is the brightest, which is directly in front of and perpendicular to its surface. A screen that reflects back 80% of the light reflected from the white reference board gets a rating of 0.8 gain. If a screen reflects 50% more light than the board, its gain is 1.5.

Gain is usually inversely proportional to the screen's diffusion angle. In other words, the higher the gain, the narrower your viewing area will be. When light hits a screen, it scatters in many directions. A viewer at the left or right edge of the screen will see an image that's about half as bright as the one seen by anyone sitting in front of the center of the screen. This is the edge of the screen's "viewing angle." If a screen has a 120° viewing angle, you can move 60° in either direction from the center and still have an image half as bright as the one seen at the center.

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High-gain screens are typically designed for use in classrooms or multimedia environments. Their narrow viewing angle makes them a poor choice for most home theaters. Some glass-bead screens (also known as retro-reflective) are especially good at reflecting light directly back in the direction of the projector. These are best used when you have a projector mounted on a table and want to show the image in a small viewing area, such as a conference room. Although high-gain screens definitely have their place, they tend to suffer from hot-spotting, where the image is reflected unevenly across the screen as viewed from a single seating position, causing some areas to be brighter, or "hotter." Many high-gain screens also suffer from color shifting, meaning that they treat red, green, and blue differently, so they're usually not what you want to be using in a critical viewing environment such as a dedicated home theater.

Aspect Ratios

The Next Step in Screen Technology

Projection-screen technology for the home has come a long way from the basic pop-up screen in the 8mm days to the fantastic realms of dedicated rooms and 1.78:1-format widescreen images. Some even say we're on the verge of another big leap in home theater with the introduction of products such as Stewart Filmscreen's 2.35:1 CineCurve screens, which are indeed curved. These super-wide screens have been around for a while, but they've only recently been gaining serious consideration for the typical dedicated media room — thanks to the popularity of Runco's CineWide system, which uses anamorphic lenses to create 2.35:1 images that completely fill the screen. At the moment, achieving this requires a considerable investment in projectors, lenses, scalers, screens, and control systems. But as with all technology, the prices will continue to fall.

Thanks to the advent of widescreen TV, the average person has become aware of the term "aspect ratio." Although many people still might be a little confused by measurements such as 4:3, 2.35:1, and 1.78:1 (which describe the screen proportions, with the first number representing the width and the second the height), they're having better luck grasping the difference between widescreen and full-screen TVs. Projection screens are available in several formats, including standard TV (4:3, or 1.33:1) and widescreen HDTV (16:9, or 1.78:1) as well as CinemaScope (2.35:1 or 2.4:1). Most home theater projectors use 16:9 HDTV as their native format, and most installations today use 16:9 screens.

I usually design mid-level home theater installations so the owner has the option of upgrading the screen to 2.35:1. HDTV is still the main focus in these home theaters, and most clients are willing to live with the black bars above and below the image during any 2.35:1 movies they might watch. In higher-end installations, anamorphic lenses can be used with a standard 16:9 projector to display an image on a 2.35:1 screen. (See "The Next Step in Screen Technology".) Motorized masking closes in the sides for 16:9 viewing. Screens built for this kind of viewing are also known as "constant height" screens. At the moment, however, it requires a decent amount of money to make the experience of using one of these systems seamless.

Acoustical Transparency

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Perforated vs. Woven

Top: Almost all screens designed to allow you to place speakers behind them are perforated — that is, they're covered with regular rows of circular holes. Bottom: Woven screens use an irregular weave that, some claim, enables the screen to be more acoustically transparent.

The screen industry has been using a term — "acoustically transparent" — that many of us still find amusing. (In the field, we tend to call these screens "acoustically translucent.") The material used to create a perforated or woven screen will always have some effect on the sound coming from any speakers placed behind it. A debate continues to rage over how best to minimize the material's impact on the sound while maintaining a clean image on the screen. Some of the screens I've used from companies such as Stewart Filmscreen allow for clear sound while producing an excellent projected image. Other screens I've tested look like you've just installed a block of Baby Swiss cheese. Quality can vary a lot with acoustically translucent screens.

A favorite screen of mine for this application is Screen Research's ClearPix2. This woven screen is both THX- and ISF- certified. In my opinion, its ability to allow sound to pass through unhindered is astounding, and the images are clean and crisp. On the other side of the debate, Stewart is adamant about the superiority of its perforated screens (see Sound & Visionary: Grant Stewart), and I have to admit that when I recently ordered one of its screens for a prominent Hollywood director, the quality was excellent both visually and sonically.

Build Quality

When you finally decide to invest in the screen of your dreams, make sure to look at its overall build quality — especially if you're considering a motorized screen. Some manufacturers cut corners by making their screens a little more difficult to assemble or by skipping the tensioning system necessary to keep the screen tight and flat over time. Some discount screens are even attached to the frame with Velcro. Screens like these usually have to be taken down and re-tensioned by hand over time.

Issues such as the border's fit and finish might be of greater concern. High-quality miter corners with a black-velvet coating, which absorbs stray light, are usually the way to go for a fixed-mount screen. Black fabric or wood frames might not help with any overscan that occurs and could distract you from the image.

Motorized Screens

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Flat vs. Curved

With a flat screen (top), some of the light disperses away from the left and right sides of the image. With a curved screen (bottom), that light is reflected back toward the picture area, creating a brighter image.

If you're looking at a motorized screen and the price seems too good to be true, it probably is. You'll find several motorized models selling for less than $500. These seem to work about once for every hundred dollars you spend, so if you want the unit to raise the screen more than five times, spend a little more and get a decent motorized chassis and good screen material. The motorized version of Screen Research's ClearPix2 woven screen is quite good. Draper also has some great tensioned and nontensioned screens available in motorized units with a variety of screen materials to choose from.

Making the decision to buy a high-quality screen is half the battle. With all of the choices available, deciding on which is the right screen might seem a bit overwhelming at first, but remember that a chain is only as strong as its weakest link. The last major item in an audio path is the speakers, and the last video item in a front-projection home theater is the screen. Consult with a home theater professional if you're still not sure which screen to buy, or if you'd just like to take a look at more of the available options. Many CEDIA members have demo rooms and will be willing to help you find the best screen solution, even if it's for a do-it-yourself project.

Sean Greer is both the owner of and senior design engineer at Experience AV Home Theater (ExperienceAV.com) in Montrose, Colorado.

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