Re: Telebinocular viewer

[P3D Alan Lewis <dlewis@xxxxxxxxxxxx>]

P3D Peter Abrahams wrote:

> The newly created viewers under discussion are made with lenses sawn in half
> and transposed.  Why not use two whole lenses, and mask the 'converging'
> (outer) half?

This can be done but is both twice as expensive and takes up twice as 
much lateral room as the cut in half approach.  Almost all Holmes/Bates 
scopes (Both new and antique) have been made with two half lenses 
generated from one solid lens, or at least two half lens blanks butted up 
against each other to look like a solid one piece lens.  The antique 
method was to hand split the lens into two halves.  The modern approach 
is usually to saw cut.

When I get lenses that haven't been cut yet I can preview their quality 
and spec's by doing what you mention.  I mask off half of each lens to 
leave my two imitation half lenses.  Then by actually cutting them in 
half I get lenses for two scopes. 

Alan Lewis


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