T3D two projection questions

["Richard M. Koolish" <koolish@xxxxxxx>]

Let's say I take out my trusty Realist and stand 7 feet from my favorite
subject and take a picture with infinity in the background.  I mount the
slide with the foreground subject at the window, so the infinity difference
between the chips is 1.2 mm.

Now imagine that I project the slide in two different locations, one is
at home on a 4' screen and the other is at a club meeting on an 8' screen.
In both cases, I sit in the ortho seat, so the angle of view is the same.

Question 1:

Assume that in both cases, the projector is adjusted to align the windows
of both images.  On the small screen, the infinity points are 57.6 mm apart.
I assume this is fine.  On the large screen, the infinity points are 115.2 mm
apart.  I assume that this isn't good because I would need to diverge my eyes.
If this is true, it says to me that even when the viewing angle is the same,
the size of the image makes a difference that we might have to take into
account.

Question 2:

If we have a 'window-at-the-screen' effect, where it appears that the stereo
window is at the screen, does this interact with the distance to the screen?
For example: on the small screen, the ortho seat is about 6' from the screen,
not too different from the original 7' shooting distance, so the image should
look pretty much life size.  On the large screen, the angle of view is the same,
but you are now 12' from the screen, almost twice the original shooting
distance.  Does this cause your brain any trouble, seeing an image at 12'
that looks like it should be at 7'?  You might conclude that the mounting
should take into account the screen distance, so you could place the subject
at the same point in space that it had when you took the picture.


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