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Stereo in the 1600's ?



It is true that although some people seemed to have some understanding of
stereo long before Wheatstone they dont seem to have made the crucal step
of combining pairs in a stereoscope or even free viewing. Cimenti and Dou
most likely just decided  just do two slightly different views of a scene
and never viewed stereoscopicaly as has been done since. Da-Vinci's camera
obscura could have ben used to draw a stereo pair but there is no evidence
he drew at all with it as other artists have used conventional camera
obscuras . Let alone view the results by free viewing or invent a
stereoscope. Cherubim De Orleans stereomicroscope still was not a
stereoscope even if it had two objective lenses and the right sort of
working distance as they would have probably been converged onto actual
objects rather than parrallel or even divergent as would be required of a
stereoscope.
 The best evidence I have come across for a steroscope before Wheatstone
was an article in the UK stereoscopic society journal No 127 Jan 1995 page
17 with the illustration in No128 April 1995 page 16/17 by Jonn Sharp . In
researching anamorphosis he went back to one of the original sources
Jean-Francois Nicerons " La Perspective Curieuse" (Paris 1638) .Figures
LXIV and LXV show a simple device of two boards attached at right angles
with two four sided obelisks at the opposite end which seem to sighting
aids for the viewer . There are no lenses so it would have to depend on
free viewing which the obelisks might make easier. On the upright board of
LXV there is pinned a picture of the original "Fascus." symbol of ancient
Rome a bundle of sticks bound around a long handled axe . (I think the same
symbol is incorporated into the chair of the statue of George washington)
.With a horizontal bar with three stars in across it and set in a hexagonal
frame. Beside this is fixed an anamorphicaly distorted version of the same
image on a six sided pyramid. From the viewing positioned the distortion
would be corrected and the idea seems to be to free view and fuse the
images to show how completely the image is restored. LXVI is more
significant it shows two "identical" portraits undistorted side by side of
a man in the dress of the time . This looks like a stereo pair but the idea
maybe to fuse this first too show how normal images can combine before
fusing the normal and distorted image of LXV also it maybe for training
people to free view .
 But the symbol from LXV is also reproduced undistorted twice on the base
board in LXVI which from the viewing position would apear foreshortened and
stereoscopic? In any event I would not have thought that the double images
could be produced accurately enough at that time to avoid accidental stereo
effects.

                                                                      P.J.Homer



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