Are Perforated Screens Okay?  

Mike,

How far back will your eyes be from the screen?

Stewart makes two types of per screens:

Standard Perf - any screen with any gain. The perfs are small enough that they dissappear from 14 feet back from the screen. Very reasonable in price.

THX Perf - uses special material. Almost 50% of the light hitting the screen goes through the screen. Gives a metallic look to films. Very expensive. Not recommended

Lee

Stewart has two styles of perforated screens. One for typically used in commercial theaters and the THX rated "micro perf". The hole diameters in the micro perf are considerably smaller.

The actual light loss from a Stewart THX micro perf will run between 8% and 9%. The human eye, however, cannot perceive a change in light intensity of less than 10%. Thus, while there would be a measureable decrease in the reflected light from the screen, you could not perceive that difference.

The THX microperf is available on all the screen materials used in their screens (except rear projection). This includes the Studio Tek, Ultramatte, Video Matte, and Silver 3D. The MicroPerf process does not cause a color shift, increase hot spotting or change off axis characteristics of the screen.

This is also true of the Cine Perf (more commonly found in commercial and military applications).

The MicroPerf are used in the screening rooms at Skywalker Ranch.

------------------
D. Erskine
DEsign Cinema Privee
www.DEsignCinema.com
Imagine what you could do, if you could do all you imagine.


[This message has been edited by Dennis Erskine (edited July 18, 2000).]

Keep in mind that a micro perf. screen with some lcd projectors(Sony 10HT), will create a moire effect that is very annoying. It depends on the pixel shape and density of your projector.

I believe I heard that another difference in the THX micro-per from Stewart is that an equalizer is provided (or sold separately?) for the center channel behind the screen.

Someone please clarify if I'm correct or not -- I see Dennis E. has already responded and he is so much more knowledgeable about this stuff than I am.

Jim

[This message has been edited by JShort (edited July 21, 2000).]

I seem to recall issues of significant hot spotting occurring on the microperf. It's like when the press the fabric to put holes in, if can flatten areas causing a differential reflection. I have not seen this, but there have been such criticisms from others.

Ted