Stereoscope optics question

[P3D <PgWhacker@xxxxxxx>]

  I've got several stereoscopes of various designs, and I need a bit of 
help with how the optics work.  Specifically, since I use the scopes for 
my own snaps, I'd like to know how to calculate the maximum infinity 
point separation for mounted prints.

    Holding a scope up to the sky and using it to focus the sun on a 
piece of paper lets you measure the scope's focal length.  The other 
thing you can measure is the distance, on the paper, between the two 
focused suns. 

? Am I correct that this between-the-suns distance is also the physical 
distance between the optical centers of the two lenses?  

? Is this also the maximum infinity point separation for mounted prints 
used with that scope?

? Does the maximumn inifinity point separation differ from the *ideal* 
IPS?

For the widely available Added Dimension lorgnette viewer this distance 
measures about 4 inches -- ? Is that the maximum infinity point 
separation for this viewer?

Thanks in advance for the help,




Greg Kane
Denver

PgWhacker@xxxxxxx





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