[photo-3d] Re: Stereo mount window differences

["John Goodman" <jgood@xxxxxxxx>]

Kind and helpful Paul Talbot wrote:

> It should be noted that aperture size has no effect on the
> position of the stereo window--thankfully so! 

Yes.     (((  but...  )))

> Which is larger, an RBT 5P mount, or an RBT 5P mount?  Odd
> question? 

Not at all. Slight variations every which way, though plastic 
should be immune from Japan's humidity. I'll never forget a 
highschool teacher who declared "there's no such thing as a 
straight line in nature."   :>)

Just for the sake of information (which often has intrinsic value 
imho), here are some mount window data taken with digital 
calipers. The figures should be considered "approximate", with 
the fourth significant figure certainly *not* accurate to 1 part in 
10,000. Not only are accurate measurements frustrated by the 
sharpness of the calipers against the softness of cardboard, but 
the mount windows aren't perfect parallelograms (my RBT 
mounts seem to have some built-in pincushion, even if this is 
not readily visible). "S" = Spicer (dimensions in millimeters)

Mount		Width		Height

S-5N			21.50		23.15
S-5RH		21.30		20.00
S-5RW		19.00		23.05
S-7N			28.00		23.00
S-7RH		28.10		20.00
S-7RW		26.00		23.10
RBT-5p		21.40		22.95
RBT-7p		28.10		22.90

I'd love to know the actual die dimensions of the windows for 
these various mounts.

What's much more relevant to the Spicer mounting with RBT 
mount jig technique, and the stereo window surprises I saw, 
are the following dimensions. These are "throat" dimensions, 
i.e. the distance between the right edge of the left aperture and 
the left edge of the right aperture.

S-5N		40.50
S-7N		34.05
RBT-5p	40.45
RBT-7p	33.80

Bingo! Two figures stand out. 34.05 vs 33.80. I had the 
window surprises (set to the RBT window, saw violation in 
Spicer) with 7p mounts, so this fractional difference must be 
the cause, or at least a contributing factor.

In the end, all this means is "mounter beware". Look carefully. 
The reward is in having things the way you want.

jeg

 

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