[photo-3d] Spicer mounting problems

[Ralph Johnston/Linda Sherman <copley@xxxxxxxxxxxxxxx>]

I mounted a few recent rolls of RBT 8-perf slides in Spicer wide 8perf
mounts. 
They look great in a viewer, but when projected in a Brackett fader projector,
had vertical alignment problems.  About 1/4 of the slides had an inch of
vertical error on the screen.  (The image was about 20 x 30")   It went away
when you pressed down on one end of the slide, and the image was correctly
mounted, but it was the slide that was tilted in the projector.  At first I
thought that the tape was bulging out on one end and flattened the tape with a
fingernail.  This only helped in a few cases.  Then I measured the slide
with a
digital caliper and found that it was tapered!  One end was 40.0mm while the
other end was 39.9mm.  Or one end was 40.0 and the other 40.1mm.  I ended up
adding tape to the narrow end which always turned out to be the left side.  I
used Scotch magic tape, not the silver tape.  This adds about the right amount
of correction.

The cut-away RBT jig only allows 0.1mm of vertical correction because the
bottom slot is missing.  A few slides need 0.2 or 0.3mm so I just mounted them
in RBT slides.  There was never any problem with RBT slides being tilted in
the
projector.

Has anyone noticed this problem?  Does it only happen with the Brackett
fader? 
The slide is held by four curved metal tabs in this design, unlike the TDC and
other projectors which push the slide down a channel.

Regards -Ralph
*****************************************************************
*   Linda Sherman/Ralph Johnston
*   WEB PAGES http://www.ultranet.com/~copley/
*      1) Photo Historical Society of New England
*      2) Stereo New England
*      3) Auburndale Community Association
*   617-527-7562
*****************************************************************