P3D Custom-modifications of Realist-format viewers for 2x2x2

[Project3D <Project3D@xxxxxxx>]

In a message dated 19/03/98  17:58:31, George Themelis wrote:

<< While we are still on the subject of 2x2x2 viewers, let me try and tackle
 the question "why are custom-modifications of Realist-format viewers for
 2x2x2, so rare?"
 
 Yes, they are rare.  I am only aware of the David Burder modification of
 the Sterolist, as an example of a successful modification.  I have been
 asked many times to modify a Realist red button for 2x2x2.  My response: 
 "I cannot do it."  Maybe Elliott Swanson can do it... I cannot.>>

As far as I know, David made his Stereolist convertion after seeing mine. I
did the first one many years ago for Bernard Makinson. It was a derivative of
the conversion that I did for myself on a Photax viewer. Both the Photax and
the Stereolist share similar optics to the Red Button, but they both score in
that they were designed to accommodate the European 45 x 107mm glass plates
used in many of the predecessors to the 35mm stereo cameras. 

The 7mm extra slide slot width, when carefully increased a little, allows a
suitable separator to be introduced to hold the 50 x 50 slides apart so that
the film chips are centred on the lenses.

It's worth mentioning that both these conversions had halogen bulbs. 6 volt
halogen bulbs, in fact, as these were all that was available. All the other
halogen bulb convertions are derivatives of these ones... <VBG> :-)
 
And more from George:

<< The problem:  The dimensions of the standard stereo mount (101 mm x 41 mm)
 are too small.
 
( Paragraph snipped about Realis mount versus 2 x 50 x 50 mounts)

 To get around this size problem, you need to open the slide slot two ways: 
 Horizontally and vertically.  David Burder did not have to worry about
 the horizontal widening because the Sterolist viewer (British copy of the
 Realist red button) -or some versions of it- came with a wider mount slot. 
 For the horizontal opening he drilled holes for the mounts to fall in place
 and put a support bar underneath.  Trying to modify the red button in two
 directions, seems like a lot of work to me. >>

On my convertions, I arranged for the separator to be on a sliding bar that
allowed the 50 x 50 mounts to drop through slots cut in the base of the
viewers when the separator was in place, but stopped standard Realist mounts
from dropping when the separator was slid out of the slide channel.
 
One of these days, I'm going to get around to converting a few more Stereolis
viewers. When I get the time...

Bob Aldridge


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