[photo-3d] Stereo mount window differences

[Paul Talbot <list_post@xxxxxxxxx>]

Re: John Goodman noticed aperture size and window setting
differences between RBT and "Spicer" mounts.  It should
be noted that aperture size has no effect on the position
of the stereo window--thankfully so!

As to whether bad batches are involved, or whether one or
the other type of mount is slightly larger or smaller,
allow me to ask:  Which is larger, an RBT 5P mount, or
an RBT 5P mount?  Odd question?  Well, today I was trying
to put together some entries for the upcoming Wichita PSA
salon, and noticed I had RBT 5P mounts with non-matching
apertures.  On one slide, with the white half forward, I
could see the back black half protruding into the white
half aperture opening on three sides.  In another slide,
the back black half protruded on all four sides.  To which
half of which mount should we compare some other type mount?

Stereo slide mount manufacturing is not perfect, so comparison
of measurements beyond a certain level of precision is not
practical.  Further complications arise when one of the
mounts under scrutiny is made of cardboard.  Paper does
not have pefect dimensional stability.  If two "identical
twin" cardboard mounts are separated at birth, and one ends
up in humid Kyoto and the other in dry Palm Springs, they
may well grow up to be somewhat differently sized mounts.

There *are* %very% minor differences in window position
between RBT mounts and Spicer mounts.  Most users would
never notice such a minor difference.  As it turns out,
however, that window difference was noted in this forum
by another eagle-eyed chap as early as Fall (Northern) 1997.

This discussion would rapidly grow far more complicated if
other mounts are brought in for analysis...so I won't do that.

Paul Talbot

 

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