[photo-3d] Donaldson viewer - more info

["Dr. George A. Themelis" <drt-3d@xxxxxxx>]

OK, here is the information I gathered from various 
personal replies.

Donaldson was a doctor and he designed a macro camera 
to take pictures of the eye.  Wolfgang Sell has a Donaldson 
viewer for viewing an uncut roll of slide film of 7p format 
(with prisms to do the R to L reversal).  Also, there are 
rotary viewers too.

My viewer takes single slides and the format matches what 
Norm Henkels emailed me:

>I believe the Donaldson format is used by ophthalmologists. It uses a
>spacing of 58mm vs. 62.3 for Realist format. The frame/aperture size is
>about 27.5mm. I get these dimensions from a box of #2427 Sigma mounts
>formerly produced by George Skelley.

I noticed when looking at Realist-format slides in my viewer, 
I cannot fuse the infinity points because the lens spacing is 
smaller than the standard Realist infinity separation, which 
agrees with what Norm wrote.  Also, from the aperture size
of 27.5mm it appears that this is 7p (and not full frame as
I originally thought) format, as Wolfgang says.

Norm is kind enough to offer to send me a sample of this mount 
and, for those interested, he has more for sale.

The price of these viewers is in the range of $200 to $250, 
I was told.  The camera runs into thousands of dollars.

This unusual camera/format system could make a very
interesting article in one of the stereo publications, I would
think...

George Themelis
http://home.att.net/~drt-3d/