Suggestions for a NO MIX Painted Screen - BenQ W1070 - Page 2 - AVS Forum
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post #31 of 37 Old 09-09-2013, 06:46 AM - Thread Starter
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I completed my screen two weeks ago, and the process went very well, with a very smooth final surface. I have intended to post some pictures but havent gotten to it yet. I will say though, that after two weeks the screen is noticeably brighter in the center of the screen and dropping off in both directions. the spot shifts left and right slightly when you change viewing angles, so I'm assuming this is hotspotting. Any experience with this, and how to correct it?
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post #32 of 37 Old 09-09-2013, 11:36 AM
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It sounds like the surface might be too glossy, as a result of having too dense and smooth a coating.

I would very lightly sand the surface using a Fine Grit sponge the re-test.

....then again, it might be the glare coming off those nail heads.....maybe?

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post #33 of 37 Old 09-09-2013, 11:42 AM - Thread Starter
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Quote:
Originally Posted by MississippiMan View Post

It sounds like the surface might be too glossy, as a result of having too dense and smooth a coating.

I would very lightly sand the surface using a Fine Grit sponge the re-test.

....then again, it might be the glare coming off those nail heads.....maybe?

tongue.gifbiggrin.gif

I thought about trying to sand it, but that thought just scares me... I don't want to make anything worse. How fine of a grit should I use? My only concern with sanding it, is that though it is very smooth, there are still very small ups and downs within the surface. If lightly sanded would it be taking the sheen off of the raised portions, and leaving the lower portions remaining? It seems this would create a grainy effect or something, but perhaps not??
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post #34 of 37 Old 09-11-2013, 06:45 AM - Thread Starter
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These are horrible screen shots below I took with my phone, and they actually make the problem appear probably 10 times worse than it actually is, but they do show the problem well.

On the top of the screen I placed three white sheets of paper, no gloss, completely flat, just for reference to see what the painted surface was doing compared to those.

If you notice the top right corner, by the far the worse, its much darker on the paper as well painted screen, which leads me to believe my projector is just uneven up there. Not sure what standard tolerances would be, or if I should contact Ben Q on this?

Also, the wall is curved maybe a 1/2" sticking out in the middle. this could also account for some of what is seen below. But based on the shots with the paper hung at the top of the frame, I'm thinking a lot of this issue might be my projector?





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post #35 of 37 Old 09-11-2013, 07:32 AM
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Is there a source of ambient light or a reflective wall to the left of the screen? Is a side wall closer on the left side? This could cause what you are seeing.
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post #36 of 37 Old 09-11-2013, 07:37 AM - Thread Starter
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Originally Posted by LFM2 View Post

Is there a source of ambient light or a reflective wall to the left of the screen? Is a side wall closer on the left side? This could cause what you are seeing.

No, the room is symmetrical with walls on both sides, roughly 2' from the edge of screen. and it was totally dark when these pictures were taken.
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post #37 of 37 Old 09-11-2013, 10:31 PM
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In looking at the first image of the blue screen dead on, the vertical uniformity of the line shown at either side of center is rock solid proof the central bow is a leading cause of your issue .For anyone to view that image and allude to that not being the case would speak of their either willfully ignoring it, or simply trying to make up some other cause to reinforce their own agenda..

Hot spotting does NOT manifest itself as a straight vertical line or such a confined area. Nor would it create such a well defined, centralized brightness as is obviously seen in the BBall images, unless the reflected light is being "Lensed" by a Convex surface. Of course the brightness will shift as you move....you changing the angle by which the light reaches you. It certainly would not bend over or around to accommodate your line of sight.....rather you would see the light shift as you go from one side of that "rise" to another....just as you would see a shadow shift when you walk past the object creating it. Your problem is diametrically the opposite of the same issues many early CRT owners faced, that led then to utilize Concave Screen surfaces...ones that brought the sides in closer to focus light at the edges toward the viewer.

You have no "uncontrollable" Mica going against you. You have screen surface irregularities and poor Projector light uniformity. Combined they both amount to an almost intractable situation.

That you chose a DIY paint that has gain and contrast enhancement abilities does accentuate your problems, but that is not to say the paint itself is a culprit. It is simply along for the ride.

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