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Topic: Blacker blacks
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Joined: Mar 2, 2008
Posts: 43
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I have about 300 houors on my projector now and love it. One problem that I knew about before I bought it was the black levels it could produce. I have tried messing with the black levels but even the increased black setings seem to make the blacks overpowering. My screen I made myself with a sheet of black out cloth from the fabric store.

I guess my question is if there is anything I can do to help the projector acheive better blacks? New type of fabric is possible but buying a high dollar screen is not an option I am willing to commit to right now. So any ideas would be appriciated. Maybe a grey color screen cloth.
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Joined: Mar 27, 2005
Posts: 459
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You are correct a grey screen will help with that projector, also work with the room to keep wall,ceiling, and floor reflection down to a minimum.
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Joined: Aug 8, 2005
Posts: 4,417
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I am a blackaholic so trust me when I say I know more about blacks and what to do about it than anyone here pretty much. Unlike many others I don't believe that darkening floors, walls, and ceilings will make much difference in the majority of cases. The reason for this is simple- "Been there, done that". And the reason why is that when blacks are meant to be most noticable is when there is little light on the screen.

Well during those times there is also little or no reflecting light that makes it to walls, floors, or celings that is strong enough to bounce back to the screen much less be able to even see the walls or celing illuminate from it. Where brighter images are concerned, the iris of the lens allows much more light through thus washing out blacks anyway. In both cases reflecting light is not likely to hurt the image much at all. Windows or high glossy surfaces-yes however.

Of course the brighter a projector is then such regulations might be more in line with reality and light from reflective sources can hurt an image. Especially if you have a high gain white screen.

So the answer is a flat medium gray screen that is non-reflective. I have made several using a simple flat latex paint. It disolves reflective light, combats ambient light, and improves blacks significantly.

It seems a shame to know that LCD rated at 7500:1 contrast still can't produce good blacks. Most DLP I have used with as little as 3000:1 can do better for certain.
[Edited by Natja-ss-1334 on Dec 30, 2008 at 4:21 PM]
Experienced with Yamaha Dpx-830sl, Mitsubishi HC1500, Infocus SP7210, Optoma HD80, Optoma H78DC3, Optoma H27,Optoma H31, BenQ 6100,Infocus 4805, and many others.
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Joined: Mar 2, 2008
Posts: 43
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The projector has not been a disappointment at all, don't get me wrong. I probably would not even be worrying about it or noticing it if I wasn't reading forums like this. Just to know that there can be better is a little frustrating if it takes nothing but money to get.


Now, will the grey screen hurt my contrast or color that I see now? My HT is 100% light controlled.
I've tried to keep the reflection to a minimum also but I still gotta listen to the better half on some things.
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Joined: Aug 8, 2005
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No gray is a neutral color and is a perfect match with most projectors. It won't effect color at all. It may in fact enhance it's depth even. It will cause brightness to lower a small amount but the difference is minimal as long as the gray you use goes no deeper the neutral gray or medium gray. It will enhance contrast and blacks. If your contrast is already deep it will make it appear deeper, or the difference between the brightest brights and blackest blacks will appear enhanced. But in reality the brighter is not enhanced, only the darker, but the end result fools the eye's into thinking that the image increases in the brightest areas when in fact only the darker areas are enhanced.

The way this works is that many digital projectors can produce a large difference between white and black, but the lamp produces enough lumens so that an iris for example cannot prevent all the light from the lamp for reaching the screen when it is not meant to be there. what is left over is dull gray light. The gray screen is darker so it absorbs the dullest gray light so that the image appears blacker when total black is meant to be seen.

To find out just how much excess light comes out of your projector that is not meant to be there, use a simple piece of white printer paper. Find some segment in a movie that is total black, like the black area between a fade out and fade in of a film, then freeze frame it. Put the paper about 3' in front of the projector and you should see a white rectangle on the paper. Now step back guiding the paper in the path of the lens as you go back toward the screen and watch as the light lessens.

By the time you reach the screen the light will still be there. Now paint the same paper with medium gray paint and do the same thing again and observe how much less light is present on the paper.

I once tried an experiment which you can do your self. Using enough sheets of paper to cover half my screen, I painted them medium gray and taped them together from the rear to form one large square. I then taped this section of gray paper to half of my screen and then projected dim segments from my DVD's. The side of the screen that was white lost details and the image looked rather washed out while the side that was gray rendered much better detail and superior blacks. Ever since then I use only gray screens for all projectors.

I used Optoma's Graywolf II screen but it had glass beads in the mixture of paint they used. The result caused the image to have a sweet spot. The field of vision was limited and as you move your position too far right or left the image appeared to dim. So since then I use flat latex paint and make my own screens. Blacks and contrast are the same pretty much as the grayolf was without a limited field of vision.

Take a look below at this simulated image I created. This is exactly what it appeared like to the naked eye. Below that is an idea of what shade of gray I used.
[Edited by Natja-ss-1334 on Dec 30, 2008 at 11:55 PM]

Attachments:

Simulated screen: Left white/ Right gray

474 × 245 pixels (9.63 KB)

Simulated screen: Left white/ Right gray

452 × 208 pixels (3.13 KB)
 
Experienced with Yamaha Dpx-830sl, Mitsubishi HC1500, Infocus SP7210, Optoma HD80, Optoma H78DC3, Optoma H27,Optoma H31, BenQ 6100,Infocus 4805, and many others.
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