Helmholtz

[P3D Peter Abrahams <telscope@xxxxxxxxxx>]

>This is geting off topic but I have managed to locate some references to
>upside down viewing using lenses and mirrors.
Not off at all.  Stereo perception is part of stereo photography. In this
case, inverted vision would probably cause complete failure of coordination
& motion if it were not for stereoscopy.  Visual perception in the broadest
sense might be somewhat off topic, but that science can explain many of the
mysteries of 3d photography.

>Helmholtz 1867
It is surprising that the photo3d archives contain only two references to
Hermann von Helmholtz (1821-94), (one misspelled).  This physicist &
physiology professor wrote a huge work, Treatise on Physiological Optics
(1867, 3rd ed. 1910)(in German, translated 1925), much of which reads like
photo3d ramblings.  He devoted portions of this 700 page work to his
experiments on himself, writing pages on his sense of vision that read like
a diary.
This was a leading physicist, hard core mathematical German type, who writes
in the first person of his impressions of optical illusions, motion &
perspective, depth perception, convergence, and general amateur science on
one's eyeballs.
Even the science sounds like photo3d:
>From 1910..."Ewald...rotary mechanism...pictures exposed alternately to each
eye...to get a correct stereoscopic perception."
P.666...'orthoplastic visual impressions', sounds familiar, how about
hypoplastic & hyperplastic?
His translator (James P.C. Southall, Prof. physics,)even gets in the act:
p.296, "photos often convey ..false impression of perspective because they
were taken with lenses of such short focus that it is impossible to view
them with the naked eye at the proper distance. (JPCS)"  
Pp. 673-682 are on stereo photography, base line & ortho distance.
He discusses the stereoscopes of Wheatstone & Brewster (& his modifications
to Brewster's - to adjust interpupillary distance & conversion,), the
pseudoscope, the telestereoscope, stereo drawing & photography, anaglyphs
attributed to  Rollmann as the inventor, and much more.  He claims that
Moser of Konigsberg produced the first stereo photographs, and describes
them.  'Babo' made stereos through the microscope.  J. G. Halske made
'moving stereoscopic pictures', seemingly like a Zoetrope with prisms.
Depth perception from Ptolemy, Euclid, Galen, Roger Bacon, da Vinci, Kepler,
Descartes, and later authors is briefly  discussed.
Helmholz made basic contributions to the understanding of accomodation, and
his invention of the ophthalmometer was part of that.
A truly great book, probably rare in the stores, but any major library
should have it.  At 700 pages, it takes some wading through endless Germanic
attention to detail.

> I have also found another book which gives more references and dates.

...............well, I'm on the edge of my chair here......
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  Peter Abrahams    telscope@xxxxxxxxxx
the history of the telescope, the microscope,
   and the prism binocular


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