Polaroid Interocular Calculator

[P3D Peter Abrahams <telscope@xxxxxxxxxx>]

I have been looking for a 'Polaroid Interocular Calculator', a slide rule
type of device they gave away from the 1950s to the 1980s.  I learned that
David Berenson of the Boston area had acquired some, and his e-mailed
description follows.  He did not confirm his price, which I had heard was
$45. each.  I believe I am going to drop this, as 45 for a laminated paper
rule seems like too significant an investment.  I am posting this because
it is certainly an interesting rule, someone else might want to buy one
(he's in the NSA directory), and if there's a lot of interest, one could
hope for a quantity discount.  
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The device seems to be made out of / parts printed on medium- or
double-weight  photographic paper (!) which was then laminated before cutting
to sizes (Copyrighted 1952, and in just about perfect condition).

It's a circular calculator type of device, with 4  discs (one of which has an
extended bottom with printed instructions, and another a small tab for
setting), held together in the center with an oversized grommet.

The "factors" which are set against one another to determine whatever the
variable that's being sought are (not in any real order) :  
                              a)   far distance from lens to subject 
                              b)   width of negative image 
                              c)   lens to film distance (sort of  adjusted
focal lenght)    
                              d)   near distance from lens to subject
                              e)   (theoretical result)  interocular distance

Please call if any other questions - typing is NOT one of my favorite
activities!
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_______________________________________
Peter Abrahams   telscope@xxxxxxxxxx
the history of the telescope, the microscope,
    and the prism binocular


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