T3D Re: Panum's limit

[Peter Homer <P.J.Homer@xxxxxxxxxxxxx>]

>Peter Homer wrote:
>> I have a photocopy from a book on psychology referring to the
>> "Panum phenomena".  I am not sure whether this is the same as
>> John Bercovitz was referring to as there are some differences.

To which John Bercovitz replied

>I didn't mean to gloss over this statement.  I agree that what
>you found is different from what I was talking about but I like
>your finding inasmuch as it fits in one respect with stereo as
>we photographers have observed it: the 2 degree figure fits with
>the maofd method of 1/30 of the focal length.  However the 6'
>figure doesn't fit well with stereo acuity of 6" from various
>sources.  Indeed, common acuity is listed as 1' of arc or better.
>It seemed from the way your info was presented that 6' was the
>lower end of where a stereo separation could be seen.  Is that
>how you read it?
>
>Thanks,
>John B

I was largely quoting from the photocopy from the pschology text book so
the statements are theirs not mine ,unfortuneately I dont have the title or
author to quote. It was in our library at work but like another pyschology
book with interesting information on stereopsis it seems to be no longer
there. Probably it has been moved to the main campus library where our
whole library is eventualy going. I will have another look for it though.
 They seem to me to be implying than 6' is the uper end for stereo
seperation because after that the image doubles, unless the seperation is
started at 6' and then increased up 120' or over. I realise this seems to
be at odds with the technique of using turntables to take stereo pairs
where larger angles are used but is the angle of viewing/photographing a
real object the same as used to view the final stereo pair?. Angles of 4
degrees or so are I believe used in stereo scaning EMs even a maximum of 7
degrees ,there was an article in stereo world a while back about Wheatstone
and Fox Talbot . Wheatsone asked Talbot to take some photographs with an
angular seperation to produce stereo pairs , unfortuneately Talbot took
even larger angles than Wheatstone suggested and they could not be fused
easily. Even Wheatsones suggestion would be considered excessive today
although it was fusible .I dont rember these actual angles but I believe it
was sugested that about 1 degree 7' was equivalent to "normal" stereo
vision  IE not close up. P.J.Homer



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