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Originally posted by tubby
Good points Glenn, the ability to "open it up" when viewing sports with the lights on sounds good. So you think HP is not a good choice? Most of the pj use will be for movies with the lights off. I need an electric screen and the HP at $800 (non tensioned) seems like a pretty decent solution. Should I consider a white screen? |
I think the HP will work in your situation. An angular-reflective screen would probably be better though. Let me give you some info to help you decide how you want to go.
Ambient light is bad. The only perfect solution is to eliminate it. If it can't be eliminated, then take whatever practical steps you can to limit it. After that, there are ways to lessen the degrading affect of limited ambient light upon PQ. Your primary weapon against ambient light is high PJ brightness.
The 12000 has two lamp power modes and three iris settings. In High Contrast and Low Lamp Power modes, it produces about 250 lumens after it has been pro-calibrated with a new bulb. (Before calibration it is a little brighter, but a little less color accurate.) In its brightest setting (Low Contrast and High Lamp Power modes engaged), the 12000 is three times brighter. If you use a screen gain that produces an optimal picture at night with the PJ in its dimmest modes (which are also its highest quality modes), you will have the ability to triple the PJ brightness for overcoming ambient light during the day. The 12000 is unique in this aspect.
There is no "great" screen solution for your situation, though Sony has a prototype screen under development that could possibly work for you at some point in the future. Who knows? The problem with ambient light coming from the rear of the HT is that it bounces right back at the viewer, regardless of the screen material type. The best screen for this type of situation is the Firehawk, but it doesn't have sufficient gain to work for your screen size, IMO. I tried a 12000 on a 100" Firehawk, and it was just too dim. If you used a Firehawk, you would probably need to use the PJs other Iris settings, which sort of defeats the purpose of purchasing such a high contrast PJ in the first place.
The HP is retro-reflective. It tends to send light back towards its source. To get its full 2.8 gain it is necessary to mount the PJ at about the same height as the middle of the screen. In a ceiling mount situation it produces a lower gain because it sends the light back towards the PJ versus down towards your seats. The problem is that the ambient light coming from the rear of the HT will probably not have its gain reduced in the same way. I would anticipate seeing more washout from the HP than from an angular-reflective screen because the ambient light is coming from the rear of the HT. In spite of this, I think the HP is workable in your HT because of the 12000s ability to triple its light output
An angular-reflective screen will deliver more of its rated gain when ceiling mounted than would a retro-reflective screen. A 1.8 gain angular reflective screen would be a better alternative to the HP in this situation during ambient light. When I say better I mean that your PQ in ambient light will be mediocre with that screen as compared to being really mediocre with the HP

. How important this kind of difference is to you, only you can decide. The PQ at night would likely be comparable with either screen, and its the night viewing that is most important to you.
The 12000 produces about 250 lumens in Low Lamp / High Contrast mode with a new lamp. A 92" screen is about 25 sq ft. A screen gain of 1.6 would yield a screen brightness level of 16 fL. As the bulb ages, this will drop to 8 fL, which is too dim. However, when you engage High Lamp mode the brightness will be @10.5 fL, which though below the SMPTE standard of 12 fL, is still considered bright enough on a high contrast PJ like the 12000 by many of us. If this isn't good enough, you can always put the PJ in its mid-iris position for increased brightness. A 1.6 gain screen should allow you to use High Contrast mode for the life of a typical bulb. When you engage High Bulb / Low Contrast mode this same combo will produce in excess of 40 fL when the bulb is new. That is enough to combat some ambient light.
Say you used a 1.8 gain angular-reflective screen that yielded an actual gain of 1.6 with a ceiling mounted PJ. The ambient light from the rear of the HT will experience the full 1.8 gain that the screen can produce. With the HP, you would hope to mount the PJ such that you got the same 1.6 effective gain. However, the ambient light is going to experience the full 2.8 gain that the HP can produce. So in effect, the 2.8 gain HP would be expected to significantly increase the ambient light that gets reflected .back to your eyes, compared to an angular-reflective screen of 1.8 gain.
Just what the actual gain from the HP is will vary with how high above your head it is mounted. I would shoot for a location that gives you the 1.6 gain discussed above.
good luck
Glenn