[ATM] Re: ATM visual size difference

["Bob May" <bobmay@nethere.com>]

Yes, I've got the same problem with my eyes.  At 60 years of age, I've
already goine through most of the freezing of the eye curvature and, while I
now need to wear glasses for driving, I don't need them for the more
leisurely activity of reading and watching TV when it is close.
I know that there is a definite size difference in the two images that I now
integrate (never had stereo vision at any distance before!) and I find that
I really don't use it as much as my "normal" size rate estimation of
distance to an object.  I wouldn't be supprised if the size difference
between the two images that the eyes can still integrate is larger than what
is commonly realized.  Does anybody know of any investigations on this??
Bob May
bobmay@nethere.com
http://nav.to/bobmay
http://bobmay.astronomy.net
----- Original Message -----
From: The Alarm Co. <tac@i1.net>
To: <bobmay@nethere.com>
Sent: Sunday, February 06, 2005 11:01 AM
Subject: ATM visual size difference


An interesting observation (so to speak).  I too have such a difference
between my eyes.  I don't recall the actual numbers, but I have one nearly
normal eye, while the other is extremely nearsighted.  I have never been
aware of a difference in image size, even to this day, looking for it.
However, when I started wearing glasses, the negative correction for the
nearsighted eye caused a BIG differnce in image size.  By big, I mean
holding my glasses a arm's length. the image size in one is no more than 2/3
the size in the other!  This was extremely disconcerting at first, but I got
used to it after wearing them constantly for several days.  I had a similar,
though longer, period of adjustment when, decades later, I switched to
progressive bifocals.  At first, it was just about impossible to walk down a
flight of stairs.  The positive correction in the lower part of the glasses
made the stairs look closer and therefore less steep than the rest of my
senses told me they were.  That took a couple of months to pass.
So, I think that indicates some boundaries for mismatch;  30% difference
takes a LOT of getting used to, but can be done.  This would clearly be
impractical for a scope intended to be used by the general public.  I'm
guessing the 2% difference you mention would 'pass quite unnoticed while
observing a star at focus'.  Somewhere in between should be 'momentarily
confusing, but okay in a few seconds'.

Interestingly enough, the laser eye docs are now making folks like us on
purpose.  I was in my mid-late thirties when laser eye surgery became truly
practical and routine, and I seriously considered it.  Glasses were a bit of
a hindrance to my career as a photographer.  Back then, the standard
technique was to do both eyes to 20/20 or better.  But, surprise!  people
continued to age, and in their 40's lose their ability to focus close, just
like always.  I would have had only 5 or so years without glasses, and then
would have been wearing reading glasses.  Finally, the eyedocs realized that
people like us have the best of both worlds: one near eye and one far eye.
Takes a little getting used to, but works fine for most people.  Finally,
medical science catches up with nature.  Now that I'm out of photography, if
my distant eye were just a bit better, I wouldn't wear glasses at all.

 *  Best regards, Bob
*
         *           *   *

            *         *

_______________________________________________
ATM mailing list http://www.atmlist.net/