Re: A New Beamsplitter Design

["John O. Merritt" <JOMERRITT@xxxxxxxxxxx>]

<<This approach would put
the two lenses very close together so that both views will fit on a standard
35mm frame. (The mirror arrangement is still used, to get a reasonable
interocular.)

It seems to me that the lenses could be as far apart as one wishes, but
certainly 2.5 inches (64mm) apart, with suitable optics that take in a wide
angle (such as 40 deg) and bundle it down for zig-zagging via mirrors onto
adjacent parts of a standard 35mm format (36mm wide x 24mm high), and going
onto a standard 35mm lens mount in place of the lens.  The problem with
most beamsplitters is a limited field of view, since the lens format is
split in half, and very long mirrors are needed for wider fields of view.

By bundling the rays of light down for the long zig-zag trip to the film,
much as wide-angle views are sent up the narrow tube of an endoscope,
the dual taking lenses could put a reasonably wide-angle view (two 40 deg
fov images) on one standard slide.  Then, the same attachment might be used
for projection, to get the images back off the film onto a screen, superimposed.
These ideas are not new, and not from an optical design background.  Any
comments from those who are optically savvy out there?  

Is the expense of such a dual-lens SLR attachment going to exceed the cost
of a specialized dual-lens stereo camera? Or is the existing film transport,
shutter mechanism, and exposure control in an existing SLR a big leg-up on
the total cost of a stereo camera?  A dual lens SLR attachment might have
no moving parts except for focus, and could have fixed "optimal" aperture,
relying on the SLR
typically wide shutter speed range to control exposure...


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End of PHOTO-3D Digest 1068
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