simulator makes local news

"Jose" wrote in message
. net...
Even then, I'm not so sure that it would be projected in focus without a
special lens, since the distance from the lens to a flat screen is
different (longer) at the sides of the picture as compared to the center
of the picture. With the curved screen, it would be the same distance on
the edges and the center.

I'll bet it would be more in focus. I don't think lenses are designed to
take the straightness of a screen into account, and we just put up with
blurry edges and a sharper donut.

Jose
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Jose is correct. In a former life I was a projectionist. Lenses cannot
focus clearly on a flat screen, the best we could do was to settle for a
doughnut of focus that centered on the screen. Near the edges, and dead
center things were a little fuzzy. When Cinemascope came out, the wide
format required more screen. In the "Century" series theaters, we hung 3/4
inch strips of screen material vertically between the curved overhead risers
and a curved mount on the stage. Start with the center strip, then hang two
more, one to each side of the center one, and a 1/16 of an inch closer to
the lens, and angled in toward the lens maybe 1 degree. Each pair of strips
is mounted outside the growing center group, and angled carefully directly
toward the lens. Eventually you have a very wide screen, in which each strip
was positioned exactly the same distance from the lens, and pointing right
at it. The strips had to be stretched tightly, to avoid flutter in the air
conditioning. In a 20 foot high screen there was some vertical spreading
also, but we didn't have a good way of dealing with that.

Al G

Al G writes:

Lenses cannot focus clearly on a flat screen ...

They can if they are designed correctly, but it has only recently become
possible to do that. Usually the departure from field flatness in good lenses
is small, even for older lenses.

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