[photo-3d] Re: stereobase

["sergio baldissara" <winter@xxxxxxxxxx>]

--- In photo-3d@xxxxxxxxxxx, "Steve Boddy" <s.boddy@xxxx> wrote:
> A message i saw some time back said that the franka beam splitter
> had a stereo base of about 110mm. Can anybody tell me how this is
> mesured.Is it from the centre of the outer mirrors, and what is the 
> average base for splitters.
> Thanks Steve.

I'm not sure, so I'll expose my method.
I believe it should be measured from the center of the outer mirrors,
whose distance equals the distance between the inner (right) edge of 
the left mirror and the outer (left) edge of the right mirror (or 
vice-versa).
The above description sounds like tongue-twister, so I hope the 
following sketch will avoid some headaches...   

 outer mirror windows
|----|         |----|
|    |         |    |  
|    |         |    |  
|----|         |----|
   <-------------> 
      <-------------> 
        stereo base   
of course the 2nd way is easier, but I measured the Franka and found 
abt 105mm base, so either current infos or my method could be wrong.  
According to my method the steroworld and steritar have abt 7cm base, 
but they don't fit the same focal lenghts (sterowolrd fits 50, better 
55mm, steritar is for 45mm) so separation parallax will be different.
The russian cheap SKF-1 has base =<6.5 and is made to fit 58mm lenses.
ciao dall'Italia!
Sergio