Re:Re: John SL3D Debate? ( digest 1616)

[P3D Allan Woods <allanwx@xxxxxxxxxx>]

>
>RE: I have not been getting into the details, just lurking. In this
>response John B. covers half lens and views ground glass, then covers
>other half and views ground glass. And declares that the two images are
>different! So he got stereo out of a single lens. Maybe this is what Wm.
>Carter is talkig about????
>As any part of a lens will act as a whole lens, there are infinite
>pairs??? The prism rf in ground glass of SLRs uses the wide open lens as
>a base because of this. A huge magnifying glass used to view a flat
>picture with BOTH eyes looking, will make the picture seem to be very
>3D. Is any of this what Wm. Carter is using and John disputing?? BobH
>

I think (assume) that you are very perceptive.

My take on it is that Wm. Carter is not talking about that, but
John B. is seeing it that way.

You could say there are two images produced by the lens halves, but
there would NOT BE two images if the whole field were in sharp focus.

Extracting Z-axis information is entirely dependent on the paths
of light which are "in focus" and those which are "out of focus."
Those paths are different, and filters placed at a particular position
in the light path will encode those differences.  If all light paths are
"in focus," then there is no path difference and you need then to change
the system by gross modfication, to the parallax model.

Modifying the system so as to subdivide the lens into two halves
and changing the aperture produces a different system.

allanwx@xxxxxxxxxx


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