antique window

[P3D john e peterson <joepeter@xxxxxxxxxxxxxxxxxxxxxx>]

Like everyone else's, my thinking has been much influenced by the recent,
interesting discussion <g> of how the stereo window is placed by having the
film gates or apertures offset from the center of the lenses in
Realist-format cameras.  Now I've got some related questions about the
window in old stereoviews, beginning with the arched top found on some of
them.

The arch has been discussed in this forum in the past, but no good or
specific reason for its use has been given--I think the general belief is
that it's basically just there, a convention.  Now you might recall the
mention--in recent discussion of the window--of the principle that the top
and bottom edges of the stereo window in effect have no depth, because they
just overlap, in the two images of a stereo pair, without giving any
disparity clues; the placement of the window is created by the _sides_, and
the way they're offset against the picture differently in each image.  But
that's only true of a rectangular window, and not of the top arch--the arch
_does_ have a location in depth.  Is it possible, then, that the arched
frame is used to help clarify the placement of the stereo window?  If so,
the situation is somewhat paradoxical--people have also mentioned that the
window seems to have been less of a compositional element in the 19th
century than it is now, and "violations" of the window seem to be
relatively common (I don't know whether I buy this or not, by the way).

Does anybody know how the window was placed in 19th-century stereoviews? 
Do (any, some) 19th-century stereo cameras have apertures that are offset
from the center of the lenses?  Do antique cameras vary in this regard?

These questions apply to all windows, of course, not just windows with the
arch on top--but the arch seems to be part of the question of window
placement.  And pretty plainly it's _not_ an element that is contributed by
the camera; it seems it has to be part of the printing process, and it
seems, too, that there has to be a deliberate choice involved.  Does
anybody have a good idea of how stereocards were printed in the last
century?  Or, for that matter, the more general issue of 19th-century
"stereoaesthetics" as they affect the placement of the window?

John Peterson (joepeter@xxxxxxxxxxx)


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