Re: Questions on Handmade Stereopticon

[P3D Alan Lewis <dlewis@xxxxxxxxxxxx>]

P3D wrote:
  
>I know that I need "prismatic" lenses with some magnification, but I don't know
> where to get them (Edmunds Scientific--spelling?--doesn't carry them any
> longer) or what correction to use.  Someone mentioned just cutting a lens in
> half and I have a friend who can do that, but what should the correction be?
> 
> There are probably articles out there that I missed, but any help would >be

I'll post this to the list so that maybe an archive search can help future inquiries. A 
stereoscope is a viewing device for stereo views and a stereopticon is a projection 
device for single views of a stereo viewcard.

The lens for a Stereoscope (Holmes/Bates type) for viewing 3 1/2 x 7 inch viewcards is:

Focal length: 5 diopters (200mm)

Source for purchase: Taylor-Merchant (phone 800-223-6694) sells a molded plastic version 
that is easy to mount in a routed square pocket in wood.  It is around $8 per pair.  
These lenses meet the above spec. but are of molded plastic so they are not as good as 
glass lenses, but are plenty good enough for a homemade viewer.

Make your own:  You need a 65mm dia. or larger PCX or DCX lens of a focal length of 
between 185 to 200 mm.  The lens is cut in half down the centerline.  The remaining 
outer surfaces are symmetrically trimmed to form a square lens element of about 1 1/4" . 
 The lens elements are mounted  with the fat sides out (thin sides towards each other) 
and the separation of the outer fat sides is about 3 1/2". 

Alan Lewis


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