Custom lenses required for curved screen? - AVS Forum
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post #1 of 4 Old 06-23-2001, 10:04 AM - Thread Starter
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When I suggested putting a curved screen, such as a Torus, into my theater, my installer said that I would require custom ground lenses on my projector. Apparently his reasoning is that the lenses are designed for a flat screen, and the new geometry will be sufficiently different from flat that there will be distortion or convergence problems.

My projector is a Sony G90. I can readily imagine that I may have to relocate the projector to ensure I have the right throw distance to a curve screen, depending on where it is mounted. But I'm a little surprised that there would be other problems, or at least problems that can't be corrected with the projector's built-in adjustments. Is my installer correct, does a curved screen require a lens with different geometry?
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post #2 of 4 Old 06-23-2001, 01:20 PM
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Hello

I am the only person that has ever installed an AUTHENTIC TORUS SCREEN in a home, actually two.

The Integration of a TORUS is a tricky thing, however your installer has no idea of what it's involved.

With the propper TORUS screen design the screen actually IS equidistant to the optical elements.

TOO DEEP a design= very narrow seating area may be a problem but if the seating area is equally wide the G-90 will be fine
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post #3 of 4 Old 06-23-2001, 01:56 PM - Thread Starter
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Quote:
With the propper TORUS screen design the screen actually IS equidistant to the optical elements.
The only way this is possible is if the screen is designed as a section of a sphere with the projector at the center. I don't know for certain that Stewart does it this way, but I doubt it. To do so would create an optimal viewing position at the projector, an untenable situation. Instead, I suspect that Stewart designs the TORUS to provide optimal viewing in the money seat, and only slightly-less-than-optimal viewing in the surrounding seats. In most theaters, this would probably lead to a screen with a somewhat larger radius (closer to flat).

In any case, my question is slightly different. I assumed that the lenses are designed to work best on a flat screen. Perhaps I am wrong and they are designed for a curved screen. Or perhaps it doesn't really matter very much whether it is flat or whether the screen is equidistant. Does anybody know which of these is correct?

Cineramax, you seem to be saying that the lens geometry is a non-issue. Is that what your experience has been?
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post #4 of 4 Old 06-23-2001, 02:02 PM
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The short answer is yes, the long one says that depending on the screen design, the curved s is better than the fs.
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