TWO MISNOMERS

[Paul S. Boyer <boyer@xxxxxxxxxxxxx>]

TWO MISNOMERS
commonly encountered in stereography
and to be sedulously eschewed by both
beginner and expert.

STEREOPTICON.  This is not the name for a stereoscope, but is
actually the brand-name of a 19th Century "magic lantern" projector.
The projected picture was *not* in stereo.  Somehow the name was so
catchy and euphonious that people have been applying it (often with
an air of great confidence and authority) to Holmes-type stereoscopes
ever since.
The real magic lanterns were themselves rather interesting devices.
Fueled by kerosene and later by carbon-arc, they projected large
format glass slides for group enjoyment.  Some of the slides were
photographic, but most were skillfully hand-made, painted, or even
with moving parts which enabled animation for dramatic or humorous
effect.  Some years ago the Mystic [CT] Seaport Museum had a
Victorian Day, and the evening banquet was followed by a real
magic-lantern show.  It was an experience hard to forget!

BEAM-SPLITTER.  The real beam-slitter is a semi-silvered mirror which
allows some light through, while some is reflected.  It has stereo
applications, if one wishes to construct a cumbersome box arrangement
allowing two SLR cameras to achieve effective lens separation down to
nothing.  It's the only way I know for getting lens separations that
small!  However, the term is generally misapplied to mirror- or
prism-devices intended as add-ons on a 35-mm camera, and yielding
half-frame pairs.  There is no real beam-splitting in such devices.
Is there a good, legitimate name for those mirror- or
prism-attachments?


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