P3D Mounting to infinity vs. to the window

["Dr. George A. Themelis" <DrT-3d@xxxxxxxxxxxxxxxxxxxxxxxxxxx>]

It is possible that Mark's question is related to the debate of
mounting to infinity or to the window...  Here are my comments:

There is something else called "mounting to infinity".  This means 
that the two chips are separated so that the infinity points are at a 
constant distance.  On school of thought believes that this is the 
correct way to mount slides.  The infinity is always at the same 
distance. (If the projection is set properly, the infinity points are 
separated by 2.5 inches on the screen and naturally the eyes are 
directed parallel when looking at infinity.)  Using this method, the 
near points fall wherever they may.  

The other school of thought advocates "mounting to the window" where the 
chips are positioned so that the near object is at, or near, window level 
and the infinity falls wherever it may.  People using this method claim 
that it produces the most pleasing results.  

Who will you believe?  Read this and decide:

If you have a stereo pair from a Realist-format camera with a depth range 
from 7 feet to infinity then both techniques will give you exactly the same 
result.  

Now, assuming that the scene has infinity.  Then...

If the near object is further away from the camera than 7 ft, then with 
the first method there will be lots of empty space between the window and 
the near object a situation.  Proponents of the second school claim that
this is not pleasing.  By placing the near object close to the window,
the infinity points are separated less than the standard distance.  That's
no problem according to the "window" school.

Now, if the near object is closer than 7ft to the camera then with the
first method the near object will be in front of the window.  In many 
cases this can be a violation of the stereo window, hence not pleasing.
By following the second method, the near object will be at window but
now the far objects will be separated by more than the standard infinity
separation.  Depending on how the projection is set it might be possible
that the eyes are strained and viewing the infinity points is uncomfortable
or impossible because the eyes are called to diverge.

Can anyone guess which school I belong to??? :-)

George Themelis

PS. For print makers, these basic conceps apply to both slides and prints
but because viewing the image with a viewer (as in prints) offers more
flexibility in terms of eye convergence, it is not a serious issue for
prints as it is for slides in projection.


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End of PHOTO-3D Digest 3298
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