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AT screen question

737 Views 13 Replies 5 Participants Last post by ahajr143, Feb 19, 2014

iron-marshal

Discussion Starter · Feb 11, 2014

I'm in the early stages of planning my new theater room and have some questions about a DIY AT Screen. I had posted a while back, planning on using a fixed, painted Silverfire screen. Due to increased business travel and radon remediation in the basement, I'm just now getting ready to start. In the intervening timeframe, I've had a chance to rethink my approach. My wife wanted to lay out the dedicated home theater in a configuration that meant that I would have to use a painted screen, but meant that I would have to settle for a 3.1 sound system since the space opens to another room and the side wall to the right of the seating area is 10 feet away.

On the other hand, if I change the layout to my preferred arrangement, I can use an AT screen, and accommodate 7.1 surround sound (the reason is because the screen in her layout was in an alcove area, which I will now convert to a seating area, using the rear and side walls for speakers). Also, having no side walls near the screen in this arrangement means no worries about light reflection as I have black ceiling panels.

The ceiling height is 92" and the seating distances will be 13.5' and 18'. If I go with a 120" 16:9 screen then those seating distances conveniently work out to 1.2 and 1.6 respectively (THX and SMPTE optimal distances). Projector is an Epson 5020 and I'll also be able to completely control lighting.

Questions:

1) I know the Silverfire screen is as good as you can expect in terms of image quality. Do you think the tradeoff to an AT screen and having 7.1 sound is worth the loss of image quality?

2) How much of a tradeoff in image quality will there be if I use a spandex screen?

3) I've read that spandex screens can have a blue shift. Can this be calibrated away?

4) any guidance on projector placement would be greatly appreciated.

Thanks for all the help.

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awblackmon

· #2 · Feb 12, 2014

Having built several DIY painted screens and then building AT screens will give your question a go. I have not noticed a lot of lumens drop off from the painted screens to my AT screen. Oh for sure there would be some but not to the point that I minded at all. The benefit of having an AT screen made any light loss to be not a big deal for me. What I gained was the extra room due to not having towers in my theater any more. Focusing just on the image I am very pleased with my AT screen.

With your being able to go from a 3.1 system to a 7.1 system if you do the AT screen would be a tipping point for me. I would defiantly build the AT screen for the benefit of the 4 surround channels to be included. Building the screen has been documented in so many threads you should be able to find a suitable way to get yours built. Good luck on your project whatever you decide.

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MississippiMan

· #3 · Feb 12, 2014

A 5020 does have sufficient lumen to push an image onto a White over Silver/Gray Spandex Screen of 120" diagonal...or less, without a "Gross" loss of reflected brightness,

An AT screen will, as stated above, reduce Foot Lambert reflective brightness, and just how much will most definitely be commensurate to how bright the PJ starts out, what Modes it is playing in (Cinema - 3D ) and the Throw distance / Screen size. As such I cannot agree that that the loss of reflective brightness it is not a big difference between AT and a well chosen Painted surface. I have found over many dozens of examples I have painted compared to the 4-5 Spandex Screens I've done that the difference is substantial.* Especially when Gray over White Spandex configurations are chosen. No...in any totally dark room when using White over Gray/Silver it will not be noticed...unless 3D or Dark Cinema mode is employed. But if you go jumping from Living Room Mode to Cinema the difference will be startling. Much more so with Gray over White.

*(...of course all my Spandex screens were in excess of 130" diagonal...)

There is also a slight degree of sharpness lost, although this is less an issue than the loss of off-screen brightness.

Best suggestion being use a Throw Distance at 1' of the minimum distance required for 120" diagonal, and also...go 7.1 Absolutely.

Even if you go "Painted" you want 7.1 sound.

Yes, it's nice to be able to hide the speakers...when possible...but not at the expense of being practical about image quality. So choose.......wisely.

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iron-marshal

Discussion Starter · #4 · Feb 12, 2014

Thanks to both of you for the helpful feedback and observations. I must admit that the move from 3.1 to 7.1 is the real driver for wanting the AT screen. As in all things, it's a matter of balancing the tradeoffs, and for me if I can get a still excellent picture (even if it is a slight step down), but add the entire surround sound, that beats world class image, but no surround.

I'll take the recommendation for the white over silver spandex. I assume that the Milliskin is still the preferred brand? I also thought I remembered reading somewhere that there could be differences in reflectivity depending upon where the product was ordered from (or maybe that was another product I'm thinking about). Is that true, and if so, where should I order the product from?

Thanks again for all the help.

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ahajr143

· #5 · Feb 12, 2014

This http://spandexworld.com/c3/catalog/product/795 over this http://spandexworld.com/c3/catalog/product/10921 .

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iron-marshal

Discussion Starter · #6 · Feb 12, 2014

Any idea wht the gain on a white over silver spandex screen works out to? I'm assuming 1.0, or slightly worse. Does that sound reasonable?

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ahajr143

· #7 · Feb 13, 2014

You should figure on 0.8 gain. That will be close.

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awblackmon

· #8 · Feb 14, 2014

Quote:
Originally Posted by MississippiMan /t/1517345/at-screen-question#post_24346564

A 5020 does have sufficient lumen to push an image onto a White over Silver/Gray Spandex Screen of 120" diagonal...or less, without a "Gross" loss of reflected brightness,

An AT screen will, as stated above, reduce Foot Lambert reflective brightness, and just how much will most definitely be commensurate to how bright the PJ starts out, what Modes it is playing in (Cinema - 3D ) and the Throw distance / Screen size. As such I cannot agree that that the loss of reflective brightness it is not a big difference between AT and a well chosen Painted surface. I have found over many dozens of examples I have painted compared to the 4-5 Spandex Screens I've done that the difference is substantial.* Especially when Gray over White Spandex configurations are chosen. No...in any totally dark room when using White over Gray/Silver it will not be noticed...unless 3D or Dark Cinema mode is employed. But if you go jumping from Living Room Mode to Cinema the difference will be startling. Much more so with Gray over White.

*(...of course all my Spandex screens were in excess of 130" diagonal...)

There is also a slight degree of sharpness lost, although this is less an issue than the loss of off-screen brightness.

Best suggestion being use a Throw Distance at 1' of the minimum distance required for 120" diagonal, and also...go 7.1 Absolutely.

Even if you go "Painted" you want 7.1 sound.

Yes, it's nice to be able to hide the speakers...when possible...but not at the expense of being practical about image quality. So choose.......wisely.

I have not built any 130 inch screen as MississippiMan has done. He is way ahead of me in the way of experience with screen builds. (I'm not worthy, I'm not worthy, as I bow

) I would agree that the lumen drop off for such a size screen could be pretty drastic. I kept my AT screen pretty close to the same size as my painted screen. I went from about 80ish inches to 108 inches. I could have gone larger in my room but I did not want to loose to much in the way of lumens. I also did notice there was a decrease in sharpness with an AT screen. I wanted this type of screen bad enough that I am ok with this loss.

I will agree with MississippiMan that going to 7.1 should be high on your list. You will not regret doing it. From my experience it was easier to build a painted screen. I rolled all of my various painted screens. I have a pretty soft touch and use foam rollers. My favorite size is the 4 inch wide roller with rolled edge. The rolled edge helped me to not leave edge marks as I rolled. And as I said a soft touch as you roll helps. I also sand slightly between each coat. Now if you can buy or borrow a sprayer that can help with not leaving edge marks as you paint the screen. I painted two coats of primer and then put on three top coats. I really liked what a gray paint did for my contrast and colors. I chose one that is not to deep a gray. I used Behr Silver Screen. Problem with Behr now, from what I understand, is the base formula is not what it used to be. Other brands are doing a better job now. This is all assuming that you go with a simple paint formula. There are some pretty complex paint formulas of which MississippiMan can tell you about or you can do a search about.

Choose a screen. Make a plan. Roll up your sleeves. Have some fun. That is really what this is all about.

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iron-marshal

Discussion Starter · #9 · Feb 14, 2014

How drastic is the loss of sharpness? I'm not married to the screen size of 120", but since the move to 7.1 will be easier with an AT screen I'd like to maximize my image quality within that constraint. Is there a sweet spot I should be thinking about?

My primary seating will be 13 feet, and I can mount the projector within 1 foot of its minimum throw for the screen size as MississippiMan suggests in order to maximize lumen output.

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KdxGuy

· #10 · Feb 15, 2014

I just made my first screen. It is about 125 inches and made out of the white over silvere spandex. I needed an AT screen so I could take advantage of the full wall width and put my rather large speakers behind. I have no other experience with projector setups but am real happy with the results I got. It is perfectly viewable with a fair amount of light but is certainly doesn't have the blacks and contrast like when it's dark. The 7.1 surround would be the determining factor for me. I don't think a better screen would ever make up for the full surround experience. It always bothered me having the center speaker on the floor under my TV. Now the sound is pretty incredible coming from behind the screen where it should be.

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iron-marshal

Discussion Starter · #11 · Feb 16, 2014

Do I need to do anything special when stretching the spandex to prevent moire?

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ahajr143

· #12 · Feb 16, 2014

You want to stretch it as evenly as possible and as little is necessary to remove wrinkles. Follow the stretching pattern given for blackout cloth.

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iron-marshal

Discussion Starter · #13 · Feb 19, 2014

Thanks. Do I need to rotate either layer of spandex to avoid moire?

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ahajr143

· #14 · Feb 19, 2014

You don't need to rotate either layer. Moire would be caused by stretching the material so that the texture of the weave shows. My screen is stretched more than it should be and I don't have any visible moire pattern. The milliskin (or moleskin) spandex has a very fine weave.

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