Mounting: to-win vs to-inf

[bercov@xxxxxxxxxxx (John Bercovitz)]

Could we have a discussion comparing mounting to the window versus 
mounting to infinity?  We have a lot of people who are really deep 
into this and I'd like to hear what they have to say.  I see four 
possibilites:

Projection
     mounting to the window
     mounting to infinity

Hand held viewer
     mounting to the window
     mounting to infinity

I'll kick it off with my totally biased and totally unfounded 
opinions. 

For my medium format viewer, I set the lenses and infinity at 67. 
The apertures in the mounts are made at 62.  This gives a window 
distance of 1.1 m.  I don't find that to be a problem at all.  The 
lenses are 80, closely matching the camera's lenses.  This is a 
very comfortable setup to view.  Vergence matches distance and 
although vergence is a fairly weak indicator of distance for most 
people, I think it's a plus  on the comfort scale to have it match 
distance.  If you mount to the window you lose that, but I think 
probably nothing else.  If I took a view that had objects closer 
than 1.1 m, I'd be forced to mount to the window or cut up a mount 
for the purpose if I wanted to maintain "Purity of Essence" as the 
good general said.  8-)

Projection is generally so horsed up I think this may be the least 
of one's worries.  (Projection viewing is badly stretched unless 
the photographer follows Ferwerda's advice and uses 70 mm taking 
lenses in a miniature format.  Have such lenses ever been put on a 
miniature format camera?)  So here it's probably best to mount for 
maximum viewing comfort.  When I project, I try to seat the 
audience as near to ortho as I can.  In this case, I think 
mounting to infinity is again useful.  I presently use a 4' screen 
so there are no problems with the window floating off the screen.  
When I get my 6' screen, things will be different.  Sitting at the 
ortho seat, you don't feel like you're looking at a stereo 
projection; you feel like you could just up and walk right through 
that window; it's that natural.

John B


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