lens aid for viewing stereograms

["SIMON, MARTIN D." <MSIMON@xxxxxxxxxxxxxxxx>]

George is roughly right about what you need to do to view stereograms
with an optical setup, say an old stereoscope.  A company actually
tried to market a device to stereogram makers, but as far as I know
never went into production.  I saw a prototype, which was similar
to a lornette viewer.  One side was clear flat plastic.  The other
eye looked through an array of small prisms, which slightly diverged
the sightline.  It took a little experimentation to get the distances
from the eye to lorgnette to the image correct.  Not everyone found
it easy to use but it did work.  I think you could accomplish the same
thing by holding a prism in front of one eye. (Don't use a stereoscope
lens because you don't want the magnification).


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