Re: Pre-mount viewer

[P3D Peter Abrahams <telscope@xxxxxxxxxx>]

>> correct alignment by moving the chips.
> I really can't tell correct alignment by this method.  (Do I 
>have a personal problem or _what_?) 
Or what what?

> Seems like any old placement of 
>the chips is OK for my eyes as long as...
Old binoculars are more commonly out of collimation than collimated, and
I've probably seen all types of miscollimation  they can suffer.  Most
people are not bothered by minor  convergence, and some tolerate minor
divergence.   I am not bothered by dipvergence, vertical misalignment,
nearly as much as most people; and to a lesser degree this is true for image
rotation.  This causes misunderstandings when I indicate that an instrument
is OK, so I've learned not to opine on the subject.
I have not seen any quantification, or even qualification, of this, and
would certainly appreciate a reference. 
Prolonged viewing through imperceptible miscollimation typically produces
headaches, and I imagine the same is true for deviation-tolerant stereoscopists.
 The typical user test for collimation is to view a dot or small object,
then slowly move the binoculars away from the eyes, keeping the dot in the
field of  both oculars.  If you can see it in both when a foot or so away
from your eyes, alignment is good.
When viewing a stereo slide through a viewer, the normal outward-inward
adjustment of the chips precludes a test for
alignment that uses this idea.  
I've been trying it anyway, with no conclusions except that the edge of
field distortions in my (sharp) Red Button get extremely magnified.
What I started out saying is...I believe that a magnifying viewer for
mounting chips will be very useful & interesting, but that many users will
still produce slides that provoke howls or banishment from e-lists.  It will
be fascinating to view an object move through the window & back as the chips
are moved. And the promulgator of this innovation will not claim it is a
panacea for all.  But judging what is proper will still be tough for
rubber-eyed viewers (and the inexperienced, and the bull-headed.)  Some
people's eyes just seem to fuse all kinds of aberrant claptrap.
Speaking of which...I wonder if I'm the only flexi-eyed person who gets no
thrill at all from magic eye type stuff?
\\\\\\\\\\\\\\\\\\\\////////////////////
  Peter Abrahams    telscope@xxxxxxxxxx
the history of the telescope, the microscope,
   and the prism binocular


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