Re:StereoScope optics & windows in prints

[P3D Alan Lewis <dlewis@xxxxxxxxxxxx>]

Gabriel Jacob writes:
>Intuitively one would think that the lens optical
>centers should be the same as the IPS.

An interesting exception is the Holmes/Bates stereoscope optics.  It 
seems that the discussion here has been for round, symmetrical lenses 
used in slide viewers.  But the antique lenses are half lenses and the 
optical centers are placed around 3 1/2" apart (or more).  This is to 
divert the vision outward to view the larger photos.  The original 
question related to the antique format , so I just thought I'd add my two 
cents. 
The sharpness out towards the edge of a lens is a bigger problem in the 
antique format I feel.  You are actually looking through each lens well 
off from its' optical center.  It becomes a sensitive issue with me to 
position the lenses so that the sharpness is not greatly affected.

George Themelis writes:
>Is it that in prints the window is not as important as in slides?
>Is this a fact?  Why?

No, the window is equally as important in prints.
  
I don't know the exact reasons why antique views (and some modern ones 
I've seen) don't place the window correctly.  One reason could be the 
fact of mass production and cost.  But it may be as simple as uninformed 
people involved in the production of stereo views.

The Q-VU mount and the monolith printing at Grand Photo for prints is an 
example of a correctly thought out window scheme.  The two processes 
match so that you get a correct window if you use the camera in a normal 
fashion.  They even have close up masks to correct the window.

If you mount your own prints without the Q-VU (surface glued onto matte 
board perhaps) you still have to set a window.  Trimming the prints to 
set a window is easy, and follows a similar concept as aligning your 
stereo projected images on the screen to have the near point 
superimposed.

In the print format you can have the same "coming at you" effect as you 
can in slides. 
Bad windowing can ruin a print, and I see no excuse for it. 
  
-- 
_______________________________________________________________
Alan Lewis
mailto:dlewis@xxxxxxxxxxxxx
Home of the stereo wedding package, and weekend stereo projects
http://www.arlington.net/homes/dlewis


------------------------------