T3D Re Bugs in 3D

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

I to think that the 2mm seperation mentioned by Marc Blum would probably be
achieved by some sort of so called single lens 3d SL3D where the two
perspectives are taken after the first single lens. As with the Nils Melior
camera mentioned by John Bercovitz and Greg Erker. My own experience of
this has been limited to the use of binocular cameras (IE with one
objective and two eyepieces) for stereo . I read about the polaroid and
anaglyph and "D" cap methods a long time ago and tried the anaglyph without
much success.
 More recently I was not even thinking in terms of stereo at work when I
was trying out a simple method for estimating size under a microscope where
the students had to first measure the diameter of the field of view and
then estimate what fraction of that diameter the object in question was .
The method was probably  actualy refering to a low power stereo microscope
but they said binocular so I tried one of them first. Using a Watson system
70 with a stage graticule I found I could not get a constant figure for the
diameter but was consistently gett
ing one or the other of two figures . So I blinked from one eye to the
other and realised there was a parralax difference of aproximately 1/20 of
1mm . This worked out as well under the 1/30 rule even for the close
distance involved but it did show that very small seperations  are possible
by this method if anything it needed to be increased some way. I thought
the small seperation was why I had never noticed any stereo effect with or
without the filters but I decided to try them again this time with
relatively large subjects with no cover glass so there was as much depth as
possible. This time it worked and whats more when I removed the filters to
check I found there was still stereo depth without them but the filters did
seem to improve it. I have since come across confirmation  of my own
experiences in "The Microscope" by Conrad Beck where he says "Doubt has
been at times expressed as to whether a microscope looking at an object
with a single object glass can under any circumstances give a realy
stereoscopic relief, Those who have worked with a binocular microscope do
not retain such a doubt and the explanation of the phenomena is quite
satisfactory." Actualy I would not put it this strongly I had used
binocular microsopes for years before I became aware of any stereo effect
and I am not shure that his explanation which is to long to go into here is
the only one.   P.J.Homer



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

End of TECH-3D Digest 321
*************************