Re: Binoculars (?)
Chuck Grant (grant@aretha.llnl.gov)
Wed, 19 Apr 95 15:03:37 -0700
The pseudo 3-d effect seen through binocular telescopes is widely
misunderstood. There is an actual physical effect but it does not come
from where you might first guess. The images seen in the two telescopes
are identical *IF* your eyes are positioned identically. Miscollimation
between the two telescopes does not cause a stereo effect since our
eyes/brain easily compensates for about 5-7 degrees of misallignment (if
I remember the numbers correctly). The real effect is caused by
different amounts of distortion caused by different eye positions with
respect to the eyepieces. This difference in distortion is enhanced if
the two eyepieces are not exactly parallel, giving tilted image planes
with respect to each other and entering your eyes at an angle.
Ironicly, better telescopes (wrt. distortion) give less 3-D effect.
Chuck
footnote: Distortion in this case means the optical abberation
"non-uniform magnification across the field of view". Something with
which all telescopes are subject, to some degree. The primary
monochromatic abberations are spherical abberation, coma, curvature of
field, astigmatism, and distortion.