Re: John!!!

[P3D <PK6811S@xxxxxxxxxxxxxx>]

John writes:

>Likewise, if you have seen pictures taken by this method that have 
>more depth than they should by the two-lens understanding, it would be 
>wonderful to hear about them and to hear how the existence of this 
>excess depth was determined.

My understanding is that the claim was not 'more depth' but more
'depth distinction'.  That large aperture SL3D does a better job
of distinguishing close points than two-small-aperture SL3D or two-lens 3D.

I posted a theory of why this should be true, and have a couple of
observations:  1. large aperture SL3D should be excellent for microscopic
work, where depth-of-field is not an issue.  2. large aperture two-lens 3D
should benefit from the same principle (increasing the aperture magnifies
the difference in image-point size between object-points at different depths,
which effect is most pronounced when one of the points is in the image plane)

Given #2 maybe a table-top experiment will suffice.  One camera, one
lens, one object, diffuse lighting:

  - open the lens and take picture    - #1A
  - stop down and take picture        - #1B
  - move the object ever-so-slightly to the left
  - open the lens and take picture    - #2A
  - stop down and take picture        - #2B
  - move the object ever-so-slightly more to the left
  - open the lens and take picture    - #3A
  - stop down and take picture        - #3B

repeat the last three steps to produce #4A/B through #12A/B.

You now have a series of A-pairs taken with large aperture, and a
series of B-pairs with small aperture.  The prediction is that
you can find depth in some A-pairs that you can't find in the 
corresponding B-pairs.

If true, this experiment would validate a relationship between
depth discernment and aperture size.  Aperture size is one of 
the differences between Bill's SL3D and other 3D.  The only
other one I can think of is that the two semidisk lens halves
share a common axis, which avoids the toe-in/parallel question
but has not been mentioned in connection with the depth question.

----

Reading Bill, John, Allan, and other's latest posts make me think
it's time for a nap ..urr... meditation.

Paul Kline
pk6811s@xxxxxxxxxxxxxx


------------------------------