P3D Viewers for 2 x 2 x 2

[Project3D <Project3D@xxxxxxx>]

Michael Watters, in a heart felt plea, wrote:

<<<Let's try this again...


In the event that anyone else is tired of talking about what we
should be talking about and where we should be doing it...

How about a conversation about viewers for 2x2?    I've usually used
 one of the old 50's viewers and mounted in standard sized
 mounts (mostly 7P).   I'd like to switch to something
 where I'm not forced to chop down the slides
 too much though.   What are other 2x2
 shooters using to view?   Seems the viewers
 I've seen tend to be either the ultra cheapo plastic
things or VERY expensive handtooled jobs.  Anything
in between?  Has anyone just built their own based on traditional
viewer designs?   I find myself torn between two forces when thinking
about this myself.   I really like the idea of a "stereo mount" where
you can mount the slides together.  Makes flipping through
slides in a viewer handy.  But twin 2x2 slides are
appealing in that it's easy to send one off to
be printed (if you want that) or to project in twin projectors.

mike
watters>>>

So here goes....

Once apon a time, there was a chap who wanted to be able to project his own
stereo images, but couldn't afford a Hawk projector. So he decided to use two
standard 2 x 2 projectors.

So he mounted several hundred stereo slides in GePe glass mounts and projected
them. Everything was wonderful, until he wanted to VIEW them. This had been
easy with the old Realist mounts - there were standard viewers available. For
2 x 2 x 2, the viewers were of particularly cheap quality with apalling
optics.

He tried fastening 2 Agfa Gucki viewers together with several sticky fixers
glued together to achieve a suitable inter-occular separation and allow a
hinging effect fort minor adjustments. The results were "OK" but not up to the
standard of his Stereolist and Photax viewers. 

So he looked at these viewers long and hard. They both had optics that were
well up to the standards of the "Red Button" (he assumed - he'd only seen
pictures of this mythical beast in the Realist Manual that he'd bought
new...). They both had slots that were somewhat wider than the Realist mount.

Could a septum be introduced between two separate 2 inch mounts so that the
centres would be at roughly eye separation? Could the apertures be widened to
take the Verascope (7 perf) format? (He wasn't interested in wider than that -
the RBT camera hadn't been invented!)

And biggest question of all: could one or both be converted so that they could
switch between 2 x 2 x 2 and standard Realist mounts.

Well, it turned out that they both could. The conversions were similar - the
differences being in detail rather than principle.

The first thing he discovered was that the 2 x 2 mount has to drop through the
bottom of the viewer to allow the full height of the mount to be seen. So, if
there's a slot, the 2 x 2 mounts will be at the right height, BUT the Realist
mounts will drop too far...

The solution to this was to arrange for the sliding divider that holds the 2 x
2 mounts apart to be mounted on a carrier that also has stops that cross the
slot when the divider is moved out of the slide slot, but move move out of
play when the divider is in use. Simple.

Having done all this work on the slide holders, he moved his attention to the
illumination. At this time, a new kind of flashlight bulb had just been
introduced and was available from a motion picture supplier in London's
Wardour Street. Quartz Halogen with a voltage of 5.6...

Obviously, the two D cells had to go! They were replaced with 5 Nickel Cadmium
rechargable AA size batteries. The bulb holder was modified to take the pre-
focus bulb base. The batteries were wired to a socket on the back of the
viewer to allow for charging in-situ, and a charger unit was designed that
gave a constant 50mA charging current - independant of the number of cells it
was hooked up to...

So that's the story of the switchable viewer conversions that are still in
regular use many years later.

The designs have been imitated in a number of ways since - Dr T got the idea
for Quartz Halogen lighting, secondhand from someone who had seen the
conversions.

David Burder built his non-switchable version

etc.

In my opinion the berst viewer for 2 x 2 mounted stereos unless you use
extreme wide mounts. In which case, you need a Clay Super-Viewer. (But that's
another story!

Bob Aldridge


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End of PHOTO-3D Digest 2649
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