T3D 6x9 viewers

[John Toeppen <toeppen@xxxxxxxx>]

The stereo film pairs do not need to be mounted as a pair.  Separate
right and left images allow you to use 45-50 degree outward pointing
mirrors behind your eyepieces.  I think that this was a Sir David
Brewster design. You can now use larger images. Where you had a septum,
you now have more image.

This kind of work can be the ultimate in viewing still stereo images. 
If the lenses are not right, the image may appear no larger or sharper
than a red button viewer's image. If you could afford wall sized images
you could do without lenses at all, just mirrors to allow you to see the
opposing stereo walls....

A glass wedge will bend rays at about half of the angle of the wedge.  A
low dispersion glass or polymers can be used.  Cutting lenses off center
was a classic way to do this.  Usually the dispersion (color smear) of
such lenses is objectionable.  The spherical abberation, astigmatic
effects and "bad" blur.

Mirrors in a Brewster configuration are a better value, support a larger
format at a larger field angle, provide a larger viewing pupil, and
demand less of your viewing lenses. 

John Toeppen


------------------------------