Re: [photo-3d] Re: curved projection screens (was Re: Legitimising 3D Movies)

["John A. Rupkalvis" <stereoscope@xxxxxxxxxxxxx>]

Kodak actually offered purchasers of Carousel and Ektagraphic projectors a
choice of either flat field or curved field lenses.   The reason, however,
was because of the slide, and not the screen.

If you projected glass-sandwiched slides, you wanted the flat field; if you
projected uncovered slides, the curved field would be the better choice.

I never saw mention of the effect of the Ektalite screen curve on edge
sharpness.  Since true flat field lenses are hard to make (and expensive),
it is likely that the curve did at least a partial compensation for
conventional projection lens curvature (the Ektalite curve is in the right
direction).

Were your stereo slides mounted in glass?

Anybody else have any experience with this?

JR

----- Original Message -----
From: "Peter Homer" <P.J.Homer@xxxxxxxxxxxxx>
To: <photo-3d@xxxxxxxxxxx>
Sent: Friday, October 27, 2000 4:34 AM
Subject: [photo-3d] Re: curved projection screens (was Re: Legitimising 3D
Movies)


> IN digest 323 Mike Canter wrote
>
>
> >
> > In Digest 321 Herbert C "Bob" Maxey writes:
> >
> ><<
> > Eastman Kodak once offered a screen that was also slightly curved. It
was
> > called an Ektalite Screen, and without any doubt, this was the finest
> > screen I ever saw.   >>
> >
> >To which P.J. Homer adds:
> >
> ><>
> >
> >
> >
> >How about this:
> >
> >http://www.da-lite.com/Catalog/html/triwall/da-curve.html
> >
> I was interested in this because I had not realised any curved screens
were used for slide projection. I tried them because of their highly
reflective surface but assumed the curvature was to compensate for that of
projection CRT's
> and in fact although I did not mention this in my original post I did get
distortion and even defocussing of parts of the image when I tried to
project stereo slides.Presumably because they are flat without the curvature
the screen is meant to compensate for with an equal but opposite distortion
leaving the distortion due to the screen itself. P.J.Homer
>
>
>
>
>
>