Stereogram on the "Stereo Window"

[P3D Dr. George A. Themelis <fj834@xxxxxxxxxxxxxxxxxxxxx>]

The question was asked about the "stereo window".  This is one of my
favorite topics.  The idea is simple, but since it is a visual experience,
you need to see it and experiment with it to fully understand it, rather
than just talk about it.

The following will appear in the second issue of the "Stereogram", the
newsletter of the Cleveland stereo club.  We offer subscriptions to non
members for only $12 a year (10 issues Sep-Jun).  If you subscribe within
the next two months you will receive 2 extra issues (total of 12).  The
newsletter has local news and articles of general interest, like this one. 
The next issue has a special on the Stereo Realist camera written by a
knowledgeable Realist user.  Our club was formed in May 1997, exactly 50
years from the introduction of the Stereo Realist (May 1947).  This was
just a lucky coincidence... :-)

George Themelis, "Stereogram" Editor, fj834@xxxxxxxxxxxxxxxxxxxxx

-------- From Stereogram, Vol. 1, issue 2, June 1997 --------------------

What do we mean by "Stereo Window"???

When we view a stereoscopic image it appears as if we are sitting behind a
real window, observing the scene as it unfolds behind the window.  This is
how the name "stereo window" came about.

The window is formed by the borders of the image.  There is a "window" even
in 2d pictures but it is more pronounced in stereo photography due to the
realism of the medium.  

The stereo window can be used as a compositional element in stereo
photography.  Knowing how to manipulate it properly is a big plus.  Good
use of stereo window can make the image more appealing.  Misuse of the
window can spoil a nice view.

The stereo window is controlled by changing the borders of the images. 
This can be done by either trimming the images (in unmounted prints) or by
shifting the images with respect to a fixed mask (in masked prints or
slides).  In slides where a fixed mask is used (as in Realist slides)
bringing the chips closer together pulls the window towards the observer. 
Pulling the chips apart pushes the window further back.  In projection (or
TV) the two images are usually aligned so that the window formed by the
mask is aligned with the surface of the screen so that the screen becomes
the stereo window.

Normally, the scene should unfold behind the stereo window.  However, an
object can be allowed to go through the window if it does not touch the
edges of the window.  This often creates a striking stereo effect.  One of
the competition assignments in Detroit next year is called "Through the
Window", looking exactly for this effect.  On the other hand, an object
touching the edges of the window (especially the vertical edges) and placed
in front of it, is considered a mounting error.  

If you don't fully understand this discussion you must attend the mounting
demonstrations in our next meeting! 

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