Installed a 100" stewart micro-perf screen in a clients theater room and am projecting images via a sim2 domino 30H. What I see on the screen seems to be vertical lines but then they all swerve to the left (more severe than those in the drawing below). I thought that moire was vertical lines that extended from top to bottom. Not the case here. I noticed that the screen seemed to have patterns in it from the beginning without any image and they ran from bottom left to upper right.

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Is this in fact the moire effect and if so any fixes known to any of you out there in theater land?

Sorry just looked at the post and it place all the lines in a vertical manner. Imagine them all running diagonal to the upper right.

I don't think you have a moire pattern. To see one, go to the first response I get when I google "moire effect," which is [Link: mathematik.com]

A moire pattern almost always seems to go in different directions, depending on where you are looking.

The first moire pattern you ever saw, probably, was looking through two window screens, or through a screen and a screen door. Anything where there is a pattern to two things, and the patterns are almost exactly the same. Where the patterns overlap exactly, as say in the individual wires of the screen door, there will be a thin line; where the wire from one screen is seen between two wires of the other screen, it will appear that a single wire, three times as thick as the regular ones, is there. This variation of apparent thickness is what causes the pattern in the case of a couple of window screens.

On TV, the individual lines of the picture can mix strangely with the lines of whatever is being photographed so that strange patterns occur. When you see a man's patterned shirt swirling and moving, and especially changing appearance and even color when zooming in or out, this is classic moire -- the interference of two similar patterns.

You see patterns in the screen holes? Is that what you are saying? That is entirely possible. I would guess that lots of light shining on the holes would make the holes less visible unless you are sitting too close to the screen. Have you asked Stewart Customer Service about this? They are very helpful.

Thats why they don't recomend a microperf screen with a single chip DLP. I believe it is due to a combination of the spinning color wheel and the holes in the screen.

When you use a microperf screen, there is the possibility that the holes in the screen will line up with the pixels from the projector and produce this problem, or other color problems in the imgae. Usually when you get a quote from projector, if you tell them the projector you are going to use, they will warn you(if its a perf screen) that this occurrence is possible. This is the warning verbatim:

"When using a 16:9 native fixed pixel display device with a microperforted screen, there is the psossibility it may cause a moire effect. There is an IMX Processor that may correct this problem. If you are interested in finding out more about the IMX Processor, please contact Cygnus (Shwan Kelly) at www.cgns.com for more information on this."

This sounds like the problem you are having, but I would contact your rep at Stewart to clarify.

If it is moire, there is a screen made by screen research that you can use in place of the stewart. It is woven instead of perforated but still maintains a flat acoustical signature across the full audio spectrum -1db. If you go to www.screenresearch.com you can take a look. It is a little more pricy but does eliminate moire and is certified by ISF and THX.

Looks like you have your answer, moire or less.

But, serially, thank you very much for bringing this to our attention. That is one that I never would have seen coming! But I don't believe in putting speakers behind screens, so I might never have run into it anway.