P3D Re: Projection problem

[Tom Hubin <thubin@xxxxxxxxx>]

Oliver Dean wrote:
> 
> Hi, Tom!

<snip>

> Sorry, Tom! You have it just backwards!  To make sure, I just tested
> this with both my Compco 500 and my TDC 716 projectors. What you say
> sounds logical, but it doesn't work that way!  What you're forgetting is
> that, because the slide must be projected inverted, this also switches
> the position of the left and right views in the projector, so that the
> right-eye view is being projected through the left lens, and the left
> eye view is being projected through the right lens.  With the glasses
> oriented as you describe, the left polarizer of the glasses is being
> positioned in front of the lens projecting the right-eye view, and
> vice-versa.

<snip>

> Cordially,
> Oliver Dean

Hello Oliver,

Thanx for the info. You are right in suggesting that I should have tried
the idea first. I have a borrowed TDC116 here. I should have tried it
out but my explanation seemed so reasonable to me. Always good to have
somebody check your work.

I have very little practical experience in stereo, or in photography or
projection for that matter. But as an optical engineer I can usually
make some sense out of the necessary optical arrangement.

So, now I am puzzled. I would expect the stereo slides to be mounted for
a handheld viewer. Not inverted, emulsion surface toward the viewer's
eye, right slide directly in front of the right eye. Eyepiece lens
allows viewer to focus on slide only a couple of inches away. No image
inversion. Light source behind the slide.

Then the slide should be inverted for projection but not right/left
swapped if you still want the emulsion surface on the image (screen)
side.

So what part do I have wrong? Do you mount in a handheld viewer with
emulsion side toward the light source? This would not produce the best
image quality due to viewing through the slide thickness. 

Also, I would expect that if the screen were very close to the projector
that the 62mm image seperation would require that the right image be in
the right projector so that it is on the right side for any distance
from 0 (screen at projector) to infinity. Inversion is not a problem
here. But you would want the emulsion side of the slides toward the
projection lenses to avoid spherical aberration due to slide thickness.

Tom Hubin
thubin@xxxxxxxxx