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Da-lite High Power 2.8 Gain Screen
December 17, 2009,
Life is a bunch of trade-offs. Some wise person told me that a long time ago, and never a truer word was said. And never has it been more true than in the world of projectors and projection screens. If you want maximum contrast, you can't have a super bright image. If you want a very bright portable projector, you can't have silent fan noise. If you want a super bright high gain screen, you can't have it look super bright from all angles. That's just the way life is.
The Da-lite High Power Screen, rated at 2.8 gain, is a perfect example of trade-offs. If the projector is located at an elevation very close to mid-screen level, and you are seated close to mid-screen level, dead center in the middle of the screen, the Da-lite High Power is very, very bright. If you project a 100 IRE white image, and hold a pure white 1.0 gain test card up to the middle of the screen, the test card will look medium gray against the brilliant white of the High Power screen. According to our measurements, the screen is actually 2.8 times brighter than the white test card, so the 2.8 gain spec checks out perfectly.
That's the good news. The bad news is that once you move off center viewing axis, the gain drops in a hurry. At a viewing angle of 20 degrees from center, the effective screen gain drops to 1.0. In practical terms, the screen and the white test card appear to be equally white at that point. It doesn't take much to get to 20 degrees viewing angle. If you are standing 10 feet from the screen at the center position, and then step sideways 3.6 feet either to the right or left, you are at a 20 degree viewing angle.
At 30 degrees off center, the white test card looks bright white, and the screen looks gray. This is not unusual. In fact, this is exactly what the screen is designed to do-take the light energy from the projector and throw as much of it as possible back along the center viewing axis. Since the screen cannot create light, all it can do is reflect what hits it. And since most of the light is focused directly back in the direction of the projector, the screen looks rather dim from a wider viewing angle.
The Da-lite High Power screen is great, IF you are going to use it for the purpose it was designed for. And that is to give you an extremely bright image when (a) the projector is mounted near the center of the screen, and (b) you are seated near the center viewing axis. This type of set-up is intended to overcome ambient light conditions. And you do indeed get a brilliant picture that can look as bright as a huge LCD TV when all the projection and viewing geometry is just right. All bets are off if you are ceiling mounting the projector and projecting the light energy down onto the screen, or if you are the one seated at the end of the sofa.
There are other picture attributes to be concerned with besides brightness. Black level, detail clarity, and color uniformity, to name a few. We set up the High Power screen side by side with Da-lite's JKP Affinity, and then illuminated them both with the Optoma HD8600 1080p projector, and the Oppo BDP-83 Blu-ray player. Sitting at center viewing axis, with half of the projected image on the High Power and the other half on the Affinity, the picture quality differences are easy to describe...
First, the High Power was much brighter than the Affinity, as you'd expect. The High Power looks more like a TV, while the Affinity looks more like a commercial movie theater image. But that advantage, which is obviously quite significant in some situations, is its only advantage as far as picture quality goes. Black levels were much more solid on the Affinity. But most surprising was the fact that the Affinity looked smoother and sharper. Despite the fact that the High Power fabric has a very smooth surface, its picture had a graininess and noise level that was entirely absent on the Affinity.
From this comparison it was easy to conclude the following. If we were looking for a very bright image, and we had ambient light conditions and the ability to set up the right viewing geometry, the High Power screen is a very strong choice for that environment. The Affinity will not produce anywhere near the brilliance of the High Power under those conditions. Furthermore, if we were using a lower resolution projector than the HD8600's 1080p, the Affinity's superior ability to resolve fine detail becomes moot, and the High Power is again a worthy choice.
On the other hand, if we can turn off the lights so that brilliance of the image is not the primary concern, then the JKP Affinity is capable of delivering a sharper, smoother, clearer image with deeper black levels. For maximum picture quality in a 1080p home theater, the Affinity wins hands down. We would never install a High Power screen in order to make our 1080p projector brighter, or to push the image size beyond what the natural lumen output of the projector is capable of. This is exactly what a lot of inexperienced home theater buffs try to do with high gain screens, and it is usually not a good idea. It is not recommended with this one.
So there you have it. Trade-offs in abundance. What is most important to you? How do you want to set up your viewing environment? The High Power and the JKP Affinity are two examples of screens designed for entirely different purposes. It is important to pick the right one to meet your particular objectives.
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