Private Screening Page 2

Still More Issues?

Yep. For one, there's gray screens versus white screens. Gray screens were introduced back in the day when no fixed-pixel projector could deliver deep blacks. By darkening the screen, you also darken the blacks. Of course, you're also darkening the whites, but you don't notice it because your eye sees them in contrast to the darkened blacks.

There's one more issue, too: acoustical transparency. Many home theater designers like to put the center speaker - or even all three front speakers - behind the screen. Perforated screens for home theaters have been available for years, but some feel that a woven screen offers superior acoustic transparency. Most woven screens have a black fabric backer behind the screen to increase contrast and prevent the speakers behind the screen from showing through.

Both perforated and woven screens can create moiré patterns, which are caused by interaction of the perforations or weave with the pixel patterns of projectors. But skewing the material a bit in the screen frame usually fixes this. (Most screen companies now promise that customers will have no moiré problems with their perf or woven screens.)

Screen Testing

Six manufacturers agreed to loan us screens for evaluation: Da-Lite, Elite Screens, Screen Excellence, Screen Innovations, Screen Research, and Stewart Filmscreen. Because Cinemascope-style 2.35:1 video projection is the hottest thing going in high-end home theater, we decided to ask for 2.35:1 screens measuring roughly 106 inches wide.

I got three white woven screens, one more-or-less white solid screen, one gray screen, and one black screen.

To evaluate the screens, I measured the gain at the center and in each of the four corners to see how consistent it was; poor consistency indicates a tendency toward hot-spotting. I measured the half-gain angle of each screen - that is, the angle at which a screen's gain falls to half the on-axis gain. ( With the equipment I had, this was unmeasurable on the white screens.) I measured each screen's color response to see if it reflects all colors evenly. I measured the difference in audio response caused by the acoustically transparent screens, on-axis and at 30° off-axis. Then I spent a couple of weeks watching movies and TV shows on them.

To provide a close-to-perfect working environment for the screens, I created a "black hole" in my home theater lab - a space where the screens would confront as little influence from their surroundings as possible. I painted the walls behind and to the sides of the screens black, placed a piece of black industrial carpet on the floor, and stapled a matte-finish black fabric to the ceiling. This gave me a 6-foot-deep black zone-not perfect, but better than I've ever seen in a real home theater. To evaluate the screens' performance in non-ideal conditions, I hung beige drapes on the sides of the black hole and used my Lutron GrafikEye dimming system to provide four different preset lighting levels.

I used JVC's DLA-HD750 projector as the light source for all of my testing. In order to fill the 2.35:1 screens during my subjective viewing sessions, I added a Panamorph UH480 anamorphic lens.

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