P3D Re: RBT Precision

[pd@xxxxxxxxxxxxx]

Bob_Maxey@xxxxxxxx writes:
> 
> 
> >>I would imagine that any person or group of people that designed the RBT
> >>cameras MUST be aware of this simple fact.  So, why is this happening?  Why
> >>is the camera designated 75mm spacing of lenses and not 76mm?  Is this 1mm
> >>offset done on purpose?  If yes, what is the purpose?
> 
> No Offense and with the greatest respect for Dr. T, But.........
> 
> I hardly think the designers of the RBT are unaware of how stereo
> cameras are / should be designed. As for 1mm - that is a tiny number
> to be worrying about. An RBT is not a camera designed to some
> amazing precision tolerances - it is indeed a good camera based upon
> the reviews and comments from users, anyway. It is, from all
> reports, well made and does a great job. The only way any problem
> could be determined is by testing the hypothesis that a silly little
> millimeter makes a difference.

I'm surprised at this.  A silly little millimeter is almost 3 percent
of the frame width.  That could certainly make a difference,
especially for automated processing equipment which always steps a
fixed distance between film frames.  You can say the RBT is not
designed to precisions tolerances, but I say for what it costs, it
certainly ought to be.

> If the RBT were designed to extreme tolerances, then very few on
> this list would be able to afford one. Extreme precision comes at a
> price and in the case of stereo cameras is not needed. At least in
> the mechanicals. I know some will chastise me for that comment, but
> if there is a big difference, prove it to us/me/whoever.

The RBT costs over 3 times what a new Nikon F5 would costs.  Do you
think there's a manufacturing varability of 3% in the dimensions of a
Nikon?  I doubt it.  Of course, economies of scale do come into play,
but still, a $3500 camera should be pretty precise, or it's not worth
the money.

-pd


-- 
--------
                             Peter Davis
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