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Projection Screen 101

August 22, 2008 By Geoffrey Morrison



Click the images below for bigger versions:
Vutec Screens
Screen Research - Motorized In-Ceiling ClearPix2 - image courtesy of homecinemagallery
Stewart Filmscreen StarLift
Stewart Filmscreen StarGlas
Stewart CineCurve
Screen Research TheaterCurve
Elite Screens Home Series electric drop-down screen
Planar XScreen
SIScreens' Black Diamond screen material
Screen Excellence Reference fixed frame screen

Projector's Friend

Projection screens are often overlooked, despite being looked at. Whether you're looking for a motorized screen or fixed screen, gray or white, matching your projector with the right screen can improve its performance, and perhaps the performance of your entire theater.

What's in a screen?

First and foremost, a screen reflects the light from the projector. The perfect screen would reflect all of the light from the projector, block light from the room, and create a perfectly uniform viewing surface. While some screens can do an admirable job at one or two of these, none can do all.

Some screens will focus the light more towards the seating area, but if you go too far, the center of the screen will appear brighter than the rest, and people sitting "off-axis" (as in, not directly in front of the screen) will get odd hot spots to the image. Some screens can block ambient light, but not perfectly, and these often add artifacts of their own. The goal is to find the best compromise that fits your viewing needs.

Vutec Screens

Now why wouldn’t you just want to paint your wall white? Get close to your wall, and you'll see. No matter what kind of paint you get, you just won't be able to make that surface perfectly smooth. At worst, you'll see this texture when you're watching movies. At best it can create odd reflection spots. And really, if you've spent several thousand on a projector, why not spend a little more for a decent screen to view it on?

The Regulars

The two most basic types of screens are drop down (retractable) and fixed. Retractable screens require more elaborate installation, but offer a huge "wow" factor as your screen drops down from its hidden cove in the ceiling. This setup also allows for a flat-screen TV to be used as a daytime display, with the screen coming down in front of it for nighttime movies. Fixed screens are, well, fixed. They come with a lightweight frame, and can just be hung on a wall or stood on simple stands (often supplied).

Screen Research - Motorized In-Ceiling ClearPix2 - image courtesy of homecinemagallery

Screen Size

With single chip DLPs, LCDs, and the popular LCOS projectors, a 16x9 screen of 130-inches is probably the upper limit for a decently bright image. There are certainly exceptions (some can go bigger, some can't even go that big). Best to talk with your installer to find out how large a screen the projector you have in mind can fill. Keep in mind that light decreases with screen area, so a 120-inch diagonal screen is not 20% bigger (and therefore 20% dimmer) than a 100-inch screen, but is actually 44% larger, and 44% dimmer (all else being equal).

Three chip DLP projectors are significantly brighter, and therefore can have much larger screens. You can offset some of the light lost with larger screens with a higher screen gain.

Screen Gain

Screen gain is probably the most quoted statistic. In the days of dark CRTs, this was extremely important. Now, most projectors can brightly fill most screen sizes, so high gain is less important. With a high gain screen, you can get a hot spot in the middle of the image, which can be distracting. Also, off-axis viewing is diminished. A screen with a gain of 1.2 would, in theory, be 20% brighter than a 1.0 gain screen. At least, in certain seating positions.

"Unity Gain" screens like Da-Lite's Da-Mat, Vutec's Matte White, Screen Research's SolidPix, and Stewart Filmscreen's SnoMatte 100 have a "1.0" gain, and offer wide viewing angles, with no drop off in brightness as you move off axis. As far as gain goes, you can think of these as the benchmark, and you can go brighter or darker from here.

Gray screens, like Stewart Filmscreen's GrayHawk, Da-Lite's High Contrast Da-Mat, Vutec's GreyDove, Draper's High Contrast Gray, and SI Screens' Eclipse .85 have a darker base material that darkens the whole image. These were created in the early days of DLP and LCD projectors to lower the black level by lowering the entire amount of light coming off the screen. Since most high-end projectors have a decent enough black level, these types of screens are no longer a necessity, rather a matter of preference. In larger screen sizes, the reduction in light may become a concern.

If all your seats are fairly centralized, then screens with some gain can add that extra punch, and allow for larger screen sizes with the same projector. There are many choices available like Stewart Filmscreen's Firehawk (reviewed here), Da Lite's Video Spectra, and others from nearly every other projector screen manufacturer.

It is possible to get screens with a gain of 2 or more. Unless your screen is going to be exceptionally large, you still have a CRT, or have some other abnormal situation, these types of screens should be approached with caution. Nearly every projector on the market can create a wonderfully bright image (as good or better than a movie theater's spec of 14 foot-Lamberts) on a 1.0 gain 100-inch diagonal 16x9 screen. This is plenty bright. If you're trying to combat ambient light, a light switch would do a better job, or check out one of the specialty screens later in the article.

Screen Shapes

Every current projector designed for home use has a 16x9, or 1.78:1 aspect ratio. Unfortunately, only HDTV is this aspect ratio, and nearly all movies are between 1.85:1 and 2.35:1. One of the hottest trends in the custom market is anamorphic lenses, processing, and screen masking. What this does is stretches the 2:35 image vertically to fill the 1.78:1 chip (minus the black bars). Then an external lens stretches it back out horizontally to fill a 2.35:1 screen.

Screen Research TheaterCurve

The Stewart Filmscreen CineCurve (reviewed here) and the Screen Research TheaterCurve have a built in masking system that covers the sides of the image depending on the aspect ratio. Most other companies offer masking screens.

These can be either vertical masking that drops the screen to a certain point, then covers the top to create the "wider" (or in this case less tall) image, or horizontal, that slides in to make the image narrower. Keep in mind that you are always better off getting a screen that fits the room vertically, than going wider than 1.78:1. Otherwise you're going to get a smaller screen for some material than is necessary.

Curved screens are also a possibility, though are only really necessary for very large screen widths.

For more on ultra-wide screens, check out our article Anamorphic Widescreen - 2.35:1 in the Home.

On to Perf, Specialty, RPTV, and Conclusion...

 

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