P3D Projection Optics

[John Toeppen <toeppen@xxxxxxxxxxx>]

Dr. Ron,

The optical quality of the polarizer is not so good that you would want
to have it between your film and your lens.  I understand how optical
quality is improved with the "Norland cement and good windows" approach
to correct for this.  Your lens is also not optimized for a thick window
between the film plane and the lens.  The high cross extinction and low
blue leak material that I got from Reel 3D works great on the lamp side
of the slide.

Donít bother placing the polarizers in glass as they will run too hot
and bleach out sooner.  Not only do you not gain in image quality you
can induce stray reflections and reduce your throughput light.

The Heat Absorbing green glass filter goes before the condenser.  Hold
the condenser lenses and HA filter in their sockets with spring mounts
(glass does not expansion match metal).  The guys at David White learned
that with cracked condensers in their first production models.

You also want to make sure that the condensors project the filament of
your lamp into the pupil of your projection lens to improve resolution,
light level, and avoid an image of the filament on your screen.

JT
http://home.pacbell.net/toeppen



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