Re: Curved or "warped" mount stereo cards

[P3D emdesher <emdesher@xxxxxxxxxxxxxxxxxxxx>]

On Sat, 28 Jun 1997, P3D Bill C Walton wrote:

> 
> A couple of folks asked about the curved /warped 
> mounts used by some stereoscopic  companies
>  and wanted to know the advantages of it.  
> 
> According to W,C . Darrah, in his book "The World 
> of Stereographs" published in 1977,   the curved mount 
> was adopted by B. W. Kilburn in the late 1870s and the thought
> behind it was that it supposedly increased the illusion of depth.
> Another theory, subscribed to by some knowledgeable individuals
> is that the curved mount was adopted as it cut down on the glare 
> when viewing.
> 
> Mr Singley started Keystone View company in 1892,according 
> to Darrah, so he was a rather latecomer on the curved mount.
> After its introduction by Kilburn it became the industry standard.
> 
> I know a lot of stereographers who make stereo cards, but the only 
> one I am aware of today that is producing a curved mount card 
> is Thomas A Gillam , of Perkasie PA.  He says 
> "They look cool" and I can't argue with that.
> 
> BILL C WALTON
> MUSCOGEE 3-D
> bill3dbw3d@xxxxxxxx
> 
> 
Just a guess, or speculation, about the reason for a curved card: perhaps 
the idea was to match the optical characteristics of the viewing lenses?  
As an analogy, some projection lenses are designed for glass mounted, hence 
flat, slides while others are designed to compensate for the "popping out" 
effect of an unglassed mount when it's heated.  Perhaps there was some 
optical flaw they were attempting to compensate for with the curved card?
Dennis Sherwood  emdesher@xxxxxxxxxxxx


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