[photo-3d] Re: again those figures!!!

["Oleg Vorobyoff" <olegv@xxxxxxxxxxxxx>]

Focus/convergence coupling is such a reasonable explanation of why it is
difficult to view a stereo pair demanding more than a 2 degree convergence
range.  But I am skeptical.  I am reading a book at 12 degrees convergence.
I relax my eyes.  They naturally assume about a 3 degree convergence.  The
two overlapping images of print I see remain in perfect focus.  I feel no
inclination to refocus.  So, at least in this 9 degree range, there seems to
be no coupling whatsoever.

I continue to suspect that the problem is in the shape of the images in a
photographic stereo pair.  The discomfort I feel at over 2 degrees is very
much like what I feel when one chip is rotated or has slightly different
magnification relative to the other.  My guess is that at over 2 degrees
convergence the optical characteristics of a photographic lens do not follow
the characteristics of the eye very well.  On a stereo pair, maybe the eyes
are not presented with what they expect to see when actually looking at a
nearby object.

Oleg Vorobyoff


Owen Pearn wrote:

>for the purposes of talking about the limits to fusion, our eyes do 2
>things:
>1) they accommodate (focus) so we see things clearly, and
>2) they converge so we see things singly (ie. both eyes see the same
>thing)
...
>this disassociation of the accomodation and convergence ocular reflex is
>a cause of stereoscopic viewing discomfort.