Hi--

>Great article. I came to your site for info on digital camcorders and saw
>the page "On Seeing and Perspective". I am an optometrist and have studied
>the physiology and psychology of visual perception, though long ago. I have
>practiced for 22 years and, like most practitioners, I have concentrated on
>clinical issues and forgotten many of the details of the basic visual
>sciences. You obviously have given the issue much thought and seem to have a
>very good grasp of how it works.

Thanks for the comments!

>A couple of points to consider. There is a fundamental difference in sight
>and vision. Sight is the physical process which is often described as
>analagous to the photographic process. Vision is what the brain makes of it.
> It is amazing what the brain can do in terms of interpreting and
>extrapolating from visual input.

Yes - th' ol' brain fills in lotsa holes, but I don't think it does
what people think it does convert a spherical-perspective into a
rectangular-type. Most people just aren't very aware of their
off-center vision...

>On a physical level, the difference between central and peripheral vision is
>primarily a function of distribution of rods and cones. The cones are
>concentrated in the central area, becoming less densely packed toward the
>periphery. Rods are lacking in the central area, but become more numerous
>peripherally. Only the cones can provide high resolution and color vision.
>The rods are useful for low light levels and detecting movement. Also, the
>rods are "wired" in a manner that allows form recognition.

Yes - but "looking" at it the other way, I observe acceptable shape-
recognition out to about 180 degrees, and acceptable color out to somewhat
less, but not all that far from 180 degrees (I see the green "VIDEO"
on a black Sony TV screen right now as distinctly green out to maybe 140-
150 degrees). Objects can be seen beyond 180 degrees, but not very sharply
for me - but out to nearly 180 degrees, I have fairly good sight (I can easily
see what people are doing, recognize people, see reasonable color, etc.).
(Horizontal-direction...)

>Another important point is that the retina is essentially sperical, whereas
>the film is flat. This has a huge bearing on peripheral vision and accounts
>for the ability to see around 100 degrees laterally.
>You have probably already considered all this as it is obvious you have done
>your homework. I just thought I'd add my thoughts.

Yes - the eye is wonderfully designed to see a very wide angle of view
(I place my "reasonably good vision" at something approaching 180 degrees,
rather than 100 degrees, but one can quibble about the quality...;-),
and the brain to "signal-process" to improve what is there. I think most
people don't take advantage of the width available, though (and settle for
those horrid narrow-angle "Verilux" lenses...

>This is a refreshing change from dealing with the everyday handling of eye
>diseases and injuries. Back to the workings of a healthy eye.
>Have a merry Christmas.
>Ed White MWhite4981@aol.com

Thanks, again, for writing!
One person asked why I didn't give a direct link to the camcorder
article - I answered that there is more on the page than that, and
I hoped people would find other things of interest...
BTW, check out the article on 4-way glasses - this has worked well
for me (not really "mono-vision", since the alternate "mis-corrections"
are so small...), but no-one has responded that they have tried such an
obvious solution to age-related narrowed focus range. It sure beats
tri-focals for me, and also optimizes sight for still-camera viewfinders.