Selective Dispersion of Projected Light - Page 4 - Home Theater Forum and Systems - HomeTheaterShack.com

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post #31 of 36 Old 01-27-14, 11:14 AM Thread Starter
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Re: Selective Dispersion of Projected Light

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Ftoast wrote: View Post
For transparent paint that doesn't yellow, I've heard Darmar varnish from Michael's (used for protecting paintings) holds steady despite the evils of time and UV. I think thinner paint rather than more transparent paint might help, but that would still probably require wider micron valleys, especially if a more shallow angle can cut down visual artifacts of a grooved surface.

I have an old highgain gray screen that appears to use a gentle wave pattern in a very similar fashion to your current experiment, but instead of high gloss it uses reflective particles in the paint (looks just like mica based metallic). It works well with the ridges widening the viewing cone very nicely while the vertical limits are still tight and making efficient use of the light that's projected while deflecting overhead lighting to the floor rather than diffusing it around and making itself a lighter shade.

If you find a suitable way to DIY a grooved screen as you've planned it'll make my day as I've been scratching my head about how to properly brace a solid curved screen and your alternative tackles the same issues without the problems of a curved screen!
Ftoast,

Thanks for the input. If you know who manufactured the "old highgain gray screen" you mentioned, please let us know. Maybe more can be found out about it and applied here.

My next tests will likely involve mixing the Valspar Ultra Base C Flat with the Rustoleum Polyurethane Matte. I liked how the Rustoleum was transparent...just too transparent. The Valspar was too effective so the matting agents need to be tempered.

I've been thinking about some ideas for improving the grooves as well. The intention is that the grooves have curvature. I've been using sandpaper and that likely generates grooves that don't have curvature as the abrasives used are typically very angular and not rounded. I'm keeping in my mind that maybe I could DIY my own sandpaper that would utilize fine glass beads (round) to create the type of surface I am going for.

If the semi-circular grooves can be done DIY, then the next step is to make sure the vertical cone isn't too tight. That could be fixed with a slight curvature of the entire screen in the vertical, or possibly by using a light bead blasting that ismuch smaller than the groove width. We would then have very shallow craters all over the already formed deeper grooves. That would improve the vertical cone (if needed) and also enhance the horizontal cone more.
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post #32 of 36 Old 01-28-14, 10:33 AM
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Re: Selective Dispersion of Projected Light

The screen is branded AMC. Here are some close-ups of both the front and back to see what it looks like next to The Penny of Reference.
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Selective Dispersion of Projected Light-cam00322-1.jpg  

Selective Dispersion of Projected Light-cam00324-1.jpg  

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post #33 of 36 Old 01-28-14, 02:37 PM Thread Starter
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Re: Selective Dispersion of Projected Light

Ftoast,

Hard to tell how deep the grooves are and if they have curvature...but very interesting. Have you tried a HD projector on it?
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post #34 of 36 Old 01-28-14, 03:07 PM
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Re: Selective Dispersion of Projected Light

They are very shallow and wide. They are lightly rounded and every other one is a hill with rounded valleys of equal size between; it looks like a gentle sine wave.

I haven't noticed any visual artifacts with 720p content. I'll have to move a projector really close to see how it handles smaller/tighter pixels.
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post #35 of 36 Old 01-30-14, 10:53 AM
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Re: Selective Dispersion of Projected Light

The off-the-shelf paint that I've been playing with can do some really nice stuff in the light, but unmixed they need a lot of help to enhance the horizontal viewing angles. In case you'd like something to add to your experimenting..

The middle is just an unpainted white panel.

The left is a half/half mix of Rustoleum-MetallicAccents-SterlingSilver and very cheap flat white latex (the ink roller I applied it with gave it a fairly rough texture). The left side has wide viewing angles (which may decrease if I manage a smoother roll), but doesn't help TOO spectacularly against the light as a half/half mix.

The right is FolkArt-Metallic-Gunmetalgray(thicker, acrylic) and it needs a lot of help, but can put up a really dramatic image in the brightest of days as long as the sun isn't coming in right behind the projector.

Both the FolkArt and Rustoleum paints are very similar to eachother in looks and angles, the Folk-Art is a little cheaper and has slightly darker color options while the Rustoleum goes on a lot smoother and might equalize the price difference by requiring less paint for the same amount of coverage.
Attached Thumbnails
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Selective Dispersion of Projected Light-cam00337-1.jpg  

Selective Dispersion of Projected Light-cam00340-1-1.jpg  

Selective Dispersion of Projected Light-cam00339-1-1.jpg  


Last edited by Ftoast; 01-30-14 at 11:22 AM.
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post #36 of 36 Old 01-31-14, 10:52 AM
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Re: Selective Dispersion of Projected Light

For a quick experiment I took a plastic pizza-cutter and a straight-edge to a test panel (yes it was a solid couple minutes of sawing, yes it looked silly) and painted it with a silver-metallic. The vertical viewing angles were still tight enough to make the black bars in "2.35" content fade enough that the edges blend into the dark. But, now the horizontal viewing angles are wide enough that the image's opposite side doesn't fade terribly until you are a little passed the opposite side. It still looks horrible because of my unevenly pressured and spaced roller denting, but it was cool to see how much better it could be from such a bad application of a good idea.

How well do you think painting a textured cloth would work? I have to get my hands on some corduroy!
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