Re: Focusing and DOF

[P3D Dr. George A. Themelis <fj834@xxxxxxxxxxxxxxxxxxxxx>]

>  I took some slidebar 3d's using my SLR and reversed 50 mm lens.
>Even shooting at f22 only a third or so of the scene was in
>reasonable focus.

Has it occured to you that you might be trying to photograph an object or
scene which has too much depth to begin with?  I have not had this problem
in my close-ups.

>  I heard of a camera that has fixed focus (I think) and the
>left and right lenses focused at different distances.  Supposedly
>in the resulting image your brain picks out the sharper image
>from the appropriate eye and the "whole is more in focus than
>the sum of its parts".

This is the Stereo Graphic and a home-made version of a Nimslo.  When I
first heard of this system I thought that it did not make any sense.
It still does not...  Just think about it... You are looking at a scene
that includes infinity and an object at 7 feet.  In one image, infinity is
sharp and the close object is out of focus.  In the other image, the
infinity is out of focus but the close object is sharp.  And that's OK
with your brain?  I have not encountered this situation but I can just see
myself trying to adjust my eyes to get both images sharp at all distances.

>  Has anyone tried this on macro shots?  Any idea if it would
>work?  How much difference in focus can you get away with?

It is an invitation for troulbe since the difference in focusing will
create a difference in size between the two images.  I recommend that you
find a better subject (= one with less inherent depth that can be easily
photographed at f22).  If you can not do that then just focus at the part
of the image that is of more interest (usually the front) or in the center
and let the edges fall wherever they may.

Good luck!  -- George Themelis


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End of PHOTO-3D Digest 1265
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