how is it ( gain, color accuracy, does the front speakers need much equalization compared to the 1.2mm perfored models ?).

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RP 95 suggests the radius of the screen curvature should be (Projection distance + Distance Between the screen and audience center) / 2. So if the throw is 100 feet, and the center of the audience is 50 feet from the screen, the radius of the screen curvature should be (100 + 50) / 2 = 75 feet.

Matte white screens should always be installed "flat". But unless gain screens have the proper curvature, getting uniform illumination throughout the auditorium will be difficult.

Well, you've got a few people to tell about that little tidbit!

I hate curved screens in all aspects. Every curved screen I've ever seen (even AMC's compound curved ones) causes geometric distortions of the image. I do not like the THX Broadway rectangle "smiling" at me and every tall building "leaning" inward!

I believe SMPTE also has a standard for distortion of the screen image as well...and if some theater chains followed the proper procedures to with in tolerable levels that might not occur as often.... but true enough in a way, that THX broadway trailer "blue box" points to you off the bat if your aperature plate is cut improperly or if there is too much upward angle of the screen as seen in some stadium theaters, venietting etc etc. I kind of like that blue box cause it keeps procetionists honest when framming their picture as well. And how many times have I noticed the surrounds swapped during the TEX trailer as he flys around the auditorium. OUCH!!! Some one should come out with a trailer that intentionally, while entertaining the audience, does a quick Channel ID and picture format check. As a matter of fact I wouldn't doubt if that was part of the original intent of the THX Broadway trailer.

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Please point me to one done properly. I'd like to see it. At a previous screening room I had set up, I took a string with a Sharpie marker on one end and the other end tied to the aperture and drew lines on the walls where the screen was to go (all 4 sides) and I was wholly unimpressed with the result and "bent straight lines" was annoying as always. The projector was not at any vertical angle either nor was in a position for horizontal keystoning. Now how much more accurate can you get than with a string???

That curved screen was replaced a few weeks later with a FLAT screen and I noticed no distortion whatsoever, focus was razor sharp corner to corner and although I didn't measure the difference with a light meter, I was well satisfied with the light dispersion on the flat screen.

I think Dave Bird put it best a couple of posts above, curved screens are an advertising gimmick for 35mm presentations.

Rory,

Be careful with the older "Dolby A" versions of the THX Broadway trailer, they were printed significantly high in frame! The old "DTS only" versions were the same way. The "SRD only" and "SDDS only" and the new "multi track" Broadways are the only ones properly centered in frame.

Deeply curved screens were used for Cinerama and D-150, the idea being to "surround" the audience and engage their peripheral vision. Distortion was an issue, especially in seats away from the "sweet spot" of the auditorium.

For details of our Cinerama installation see http://www.comp.brad.ac.uk/research/GIP/film.html

All the best

Unfortunate that you haven't seen any curved screens that look good. I can think of plenty that not only look good as you enter the auditorium, but look great once the show starts.

Next time your in Australia, I'll show you a few of my favourites which are sure to change your opinion.

Getting back to the original question, I am yet to see any micro-perf screens yet, but I am wondering if cinemas are starting to install them to be ready for 'digital' cinema?