Re: John!!!

[P3D <PK6811S@xxxxxxxxxxxxxx>]

Allan writes:

>All this effort defeats and eliminates the principal of SL3D - and,
>according to Bill's calculations, only reduces the resolving power
>along the Z-axis.
>[...]
>Two lenses take two pictures from two different places.
>One lens takes one piture from one place.
>
>They are different.
>One relies on parallax.
>The other relies on "focus."

Putting quotes around the word 'focus' and waving our hands over it
does not adequately explain the phenomenon.

The two-apertures-in-a-lens model both explains what happens and predicts
what should happen as the apertures are opened/closed and joined/separated,
which predictions are consistent with my own experiments.
(It works! I have pictures!)

The present catch is that W. Carter has his own experiments showing
a greater-than-expected ability to encode depth, and a theoretic
model that is consistent with those experiments.
(It works! He has pictures!)

> Come to think of it, I've noticed that more and more things have
> gotten out of focus.  Do you suppose that is yet another effect

Not at all!  Your monitor is probably aging.  

----

The Rayleigh criterion applies to two points at the same distance
from the lens.  What is the criterion for points at two different
distances?  More specifically, two points A and B on the lens axis:

  1. A in the object plane, B in front of A?
  2. A in the object plane, B behind A?
  3. A in front of B, both in front of the object plane?
  4. A in front of B, both behind the object plane?
  5. A in front of the object plane, B behind it?

The crux of the matter, using situation #1 above:

The two-aperture model predicts that we can skinny down the apertures
(while maintaining separation) and reduce B's image to two small colored
dots to left and right of A's dot.  As the distance between A and B is
decreased the three dots will converge until at some point we can't
distinguish between them _no matter how small we make the apertures_.
Moreover the diffraction effect at small aperture causes all three dots
to expand, magnifying the difficulty.

Bill's model predicts that leaving the apertures wide open
enables us to distinguish A and B at even smaller separation...
The larger aperture _reduces_ A's dot (Fraunhofer pattern) but
_expands_ B's color-coded blur.  The larger the aperture the
greater the difference.  In situations 3-5 where both A and B
are out of the image plane, enlarging the aperture increases
the difference in blurry-dot size between A and B also.

Of course larger aperture means less depth-of-field, but for Bill
that's a feature :-)

[pause while Paul switches glasses to check spelling on his aging screen]

Gee Bill, this is really simple when you think about it.

Paul Kline
pk6811s@xxxxxxxxxxxxxx


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