P3D Re Stereo Zoom microscope system to take 3d Pictures

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

At 10:55 AM 8/11/98 -0600, Bill Shu wrote:

>I am looking for a stereo zoom microscope system (4X to about 40X range)
>that can take right-eye view and left-eye view pictures.  I intend to use it
>to take 3D pictures of iris of the eye.   Does anyone know a system that can
>accomplish this?

We have a microcope at work the Olympus stereo zoom model SZ-III which goes
from 7x to 40x with  x10 eyepieces and X 1 objective. The working distance
is then 88mm but the lens seperation is 18mm so would seem to be excessive
according to the 1/30 rule . This seems to aply to all stereo microscopes
in my experience but they also use convergence or Toe in  this case the
angle of visual axes is at 12 degrees. Which works fine visualy but
theoreticaly at least could give problems of keystoning when used for
photography. I believe I have read that this is the case somewhere although
I have also read an article in the UK stereoscopic society journal
describing the use of stereo microscopes for stereo  macrophotography
although no examples were published. Personaly I have not got any further
than attatching  a Fed in place of the eyepieces set on B with a diffusing
screen in place of the film. The frame is never fully filled but there does
not appear to be much distortion and if the microscope is foccused it does
not seem to matter much what the cameras lenses are set on. With a fixed
lens camera (as most stereo's are) and with the eyepieces in place it has
been recomended that the camera lens needs to set at infinity and placed at
the "eyepoint" and focussing achieved with" relaxed eyes " achieved by
staring at infinity just before focussing the microscope. Or a better
method is to use a "telescope or one side of a pair of binoculars" (Or both
in this case) set at infinity placed over the eyepoints and focuss the
microscope while looking through it.
  Because of the need to get a small seperation you may be better with a
SL3D system as Howard Carter sugests with a single objective but unless you
use the anaglyph system it will still need two eyepieces (binocular or
biocular?) and you may need the above methods to use with a stereo camera.
 The microscope I have refered to is quite an old one and has the advantage
for stereo that that the working distance does not change with
magnification so the stereo base need not change either . But this also
means that the resolution canot increase with magnification as it does with
conventional microscopes where the lenses get closer with increased
magnification so the "angle of acceptance increases" . We have a couple of
"Mono" Microscopes which get around this by having the front element move
in towards the subject as they zoom but I dont know of stereo versions of
these and it would be difficult to do because of the need to reduce the
stereo base.
 Why do you want a zoom ? do you want continuously variable magnification ?
it seems it might be easier with a double bellows type macro system with a
reduceable stereo base.
 A little while back on this list someone enquired about a stereo camera
system originaly intended for photographing the eye which they wanted to
use for other macro work. This had a variable base so presumably a variable
working distance/magnification as well but dont know if it zoomed . It
turned out some one-else on this list had one and even had it on their web
site. Although the term was not used I think it is called a stereo fundus
camera and is mainly intended to photograph the retina of the eye. I think
there is something about it in one of my books about stereophotography
possibily one of the Tim Van Keullen books that come with some viewmaster
reels .The second one I think I will check to see if I can find it.
P.J.Homer



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