[photo-3d] Sorry about long lines

[<donaldparks@xxxxxxxxxx>]

   Sorry folks about the recent messages having no word
wrap.

   My reply software apparently resets its settings to match
the message I'm replying to.
If I reply to this list and the post I am reading has any
long line messages, it erroneously sends a reply message
with the same problem.  I've learned something.  Hopefully,
I'll do better.

I'm going to try attaching one of the long line messages to
this post to see if I've fixed the problem.

Subject: Re: focus and convergence

>    From: "Chuck Holzner"
> My son, who is 25, has good 20/20, can see far and up
close without
> glasses, could not free view the picture.  I checked and
rechecked
> alignment, rotation and window and kept trying to get him
to see the
> depth with no success.  I then figured that he may have
his
> convergence and focus linked and tried something else:  I
had him put
> on my reading glasses and try again.  It worked.

    I'm also a believer that there is a link between focus
and convergence distance that can be a source of discomfort
when broken.  When I was younger I could not parallel free
view.  I could relax my convergence to fuse the pictures but
my brain
would not let me focus the near images while my eyes were
converged at infinity.  My young eyes could easily focus on
near pictures as long as they were converged at the same
distance as the picture.  Now my older eyes can't focus that
close.  I have
to wear reading glasses to make near objects seem to be at
the distance my eyes are able to focus.  I can now parallel
free view with relative comfort as long as I'm wearing my
reading glasses.

      I went to a 3D Imax film recently that I believe was
called "Into the Deep".  It was mostly underwater scenes
that appeared to have fish swimming from 1 to 5 feet from my
face.  Needless to say my eyes were strongly converged to
follow these fish
swimming right in front of my nose for nearly the entire 40
minutes.  The polarization provided very good extinction so
there was almost no ghosting and there was no vertical
misalignment between the left and right eye images.  I found
this viewing to
be very uncomfortable, however, because the true focus for
the projected images was on the screen, about 50 to 100 feet
away but my eyes were being forced to converge at only a few
feet. -  Don

Dr. Donald J. Parks
Mechanical Engineering Dept.
Boise State University