P3D Re: TDC 116 & 2x2x2

["Dr. George A. Themelis" <DrT-3d@xxxxxxxxxxxxxxxxxxxxxxxxxxx>]

Rod Sage asked about the back channel of the TDC 116 carrier:
 
>I own a TDC 116 and have always wondered what TDC had in mind when they
>made the slide carrier back slot for 2x2 slides. Was it mostly an
>easy way to show single mono slides or did they have a special type of
>mount and viewer in mind for full frame stereo. 

Good question Rod!  

Here some background information about the TDC projector:  
It was introduced in 1949.  TDC stands for "Three Dimension Company".  
Earl Krause, who wrote the "Three Dimensional Projection" book in 1954, 
worked for TDC and wrote the instruction manual too.  

I have in front of me an older manual found in some early TDC
projectors.  This instruction manual does not have any pictures or 
schematics.  It is just text written with a typewriter.  Total of 9 
pages.  In page 7 it writes:

"The exclusive slide carrier design permits showing Stereo Realist 
slides, 1-5/8" x 4" in the front compartment of the carrier and standard 
2" x 4 1/2" stereo slides or 2" x 2" slides in the rear compartment."

What is this "standard 2" x 4 1/2" stereo slides"?  I am not sure.
At first I thought that it was the "Verascope" format which is listed
as 45 x 107 mm.  However 2" x 4 1/2" is 51 x 115 mm, close but not
exactly.  

Now, remember, when the TDC projector was introduced in 1949 there was
one American stereo camera in the USA, the Stereo Realist.  No one could
imagine that the Realist-format would become so popular to eclipse
anything else.  That's why TDC was trying to be compatible with other
formats that might have existed before the Realist.

There are viewers for the 45 x 107 mm format and plenty of slides
circulating around... Quite common in Europe, I believe.

-- George Themelis


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