[photo-3d] Constant infinity mounting - II

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

If you are using RBT mounts you can very easily
construct a tool that will allow you apply the
constant infinity separation mounting method.  Here
is how:

Your RBT mounts come with a little bag that contains the
"rails" and a strange-looking yellow tool. Most people
do not understand what this tool is for (neither do I!)
But I have seen Ron Fross from our club modify this
tool to apply a constant infinity mounting, which is 
the original intention of this tool.

So here is what I did:  First I mounted a pair from my
S1 and checked with an alignment gauge to make sure
that infinity had a decent separation.  The maximum
infinity separation in these gauges is 1.2mm but I am
using a smaller value myself (sorry, I subscribe to the
"less is better" principle).

Once the pair was mounted in the RBT mount I laid
the yellow tool over the rails and marked on the arms
of the tool the spacing of the RBT rails.  I then cut
the ends and trimmed then with a file so that this
yellow tool FITS EXACTLY BETWEEN THE RBT RAILS.

I have now created a tool that will allow me to space
the rails to achieve a constant infinity separation.

To finish the job I trimmed (with a file) the notch
that makes the tool fit at the center of the mount
only (I need to slide this tool around) and reduced 
the thickness of the tool legs so the film chips 
can run over these legs without a problem.

Here is the nice part:  It does not matter how the chips
are cut.  If the camera works by advancing a constant
number of film perforations (sprockets) (this is true for 
all Realist-format cameras and for my S1 too) then this
tool will always work for this camera!  (You might
need to make a different tool for different cameras
but a tool is always good for a given camera).

This tool is very useful for beginner who do not have
a good concept of the stereo window.  It will allow 
you to mount consistently in RBT mounts and, depending
on the kind of scenes photographed, you will do very
well in the majority of the scenes.  Small adjustments
might be needed in some slides but the majority would
be OK.

So, what do an experienced mounter to the window
(like myself) need this tool for?

To be continued....

George Themelis