Re: [photo-3d] Re: Nu-View as Video Beamsplitter

["John A. Rupkalvis" <stereoscope@xxxxxxxxxxxxx>]

Yes, "tendency" more accurately describes this relationship.

Regarding "3-D" movies in general, many of these (especially
other-than-Imax) were shot incorrectly (even individual shots in some Imax
films).  Even if they were shot correctly, they were sometimes (read
"often") projected incorrectly.  Those of you who have seen the same 3-D
film at different theaters (or even different showings at the same theater,
where complaints resulted in corrections) can testify to that.

JR

----- Original Message -----
From: "Jim Crowell" <jcrowell@xxxxxxxxxxxxxxxxxxxxxxxxxxxxx>
To: <photo-3d@xxxxxxxxxxx>
Sent: Monday, October 16, 2000 8:05 AM
Subject: [photo-3d] Re: Nu-View as Video Beamsplitter


> > from:
> > Ian P. Howard, Brian J. Rogers "Binocular Vision
> > and Stereopsis" New York and Oxford 1995, page 398,
> >
> > which shows the zone of clear single binocular vision.
> > The figure was adapted from:
> > G.A. Fry (1939) "Further experiments on the accommodation-
> > convergence relationship" Amer J of Optometry, vol 16, pp
> > 325-334.
> >
> >> From the figure you can read for example that with one diopter
> > of accommodation (looking at one meter distance) convergence
> > is possible from zero (infinity) to about 10 degrees (about 40
> > cm or 15 inch distance, with 65 mm interpupillary).
> > This might give an idea about the elasticity of the AC-link!
> > Compared to this bungy jumping is nothing...
> >
> > Abram Klooswyk
> >
>
> I think perhaps "link" is too strong a term.  "Tendency" might be better;
> when their eyes are accommodating to a given distance, most people have a
> tendency to converge at a particular distance (which may or may not be the
> same as the distance they are accommodating to; people who tend to
> overconverge are referred to as esophores, those who tend to underconverge
> as exophores).  Converging at other distances than the preferred one is
> believed to require some effort and, if excessive or maintained over an
> extended period of time, may lead to eyestrain; phoria measurement is
> becoming a fairly common component of eye exams.
>
> That said, I've never gotten eyestrain from a viewer, but have gotten
severe
> headaches (as someone else said) from some of the earlier IMAX movies.
> "Into the deep" was particularly bad, as it required quite near
convergence
> for a good part of the movie.  The more recent ones seem to be a lot
better
> in that regard.
>
> -Jim C.
>
> -------------------------------------
> Jim Crowell, Ph.D.
> Dept. of Psychology
> Cognitive/Experimental Group
> Townshend Hall
> 1885 Neil Ave. Mall
> Ohio State University
> Columbus, OH 43210
> mailto:crowell@xxxxxxxxxxxxxxxxx
> mailto:crowell@xxxxxxxxxxxxxxxxxxxxxxxxxxxxx
> mailto:crowell.20@xxxxxxx
> http://vision-lab.psy.ohio-state.edu/crowell/
>
>
>
>
>