Re: Projection and focus sharpness (fwd)

[Yiing Lin <ylin@xxxxxxxxxxxxxx>]

---------- Forwarded message ----------
Date: Thu, 4 Jan 96 15:02:00 PST
From: John Dukes <dukes@xxxxxxxxxxxxxxxx>
To: photo-3d@xxxxxxxxxxxxxxx
Subject: Re: Projection and focus sharpness

Some few topics ago when the subject of screen brightness came up, I
commented on the rather remarkable brightness of of the Kodak Ektalite,
which has a smooth "silver" surface but which sharply focusses the 
light to the viewers with a curved surface.  (It appears to be a
"spherical" curvature, but aspherics would be simple to mold on that
scale , I'd suppose.)  John B. raised the question of defocussing 
at the edges in a projection system designed for a flat screen.

Not wanting to think about the mathematics, there being masters
within our midst, I merely measured the depth of the center of the
(40 inch by 40 inch) screen compared to a corner. Roughly 2 inches.

Don't know if that comes anywhere close to defocusing, given real
world projection lenses.  (My personal circle of confusion is
unparalled.)

What thinks thee, John B.?

John Dukes

(And I hope you'll be there Saturday at NSA.  Should you, or someone,
speak about this fine group at that time?) 



 


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