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A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Star sparkle in sextant image
From: Jared Sherman
Date: 2004 Sep 27, 13:34 -0400
From: Jared Sherman
Date: 2004 Sep 27, 13:34 -0400
Jim, what you call "sparkle" is similar to the
lasik damage I have, which is a combination of increased glare (never had
problems with that before), residual astigmatism, and double/triple vision from
"ghosting" in each eye. This from what is called successful lasik surgery. As I
told my optometrist afterwards, "And they let people drive who can see like
this?!"
The glare/ghosting apparently are not unique to
lasik complications, but are "normal" eye defects in the population. A single
LED light looks like a small dot to me in daylight, against a similarly bright
background. But at night, set against a dark field, it has a "crown" around it
similar to your images. That's a glare problem, in my case compounded by the
multiple vision--which can come from physical aberrations in the normal
eye.
You might want to play with the interactive vision
simulator at http://www.surgicaleyes.com to see the
effects of glare, etc., and how they are defined, and change vision. Especially
the vision involved with a bright point against a dark field.
Astigmatism can be corrected by glasses, of course.
A pinhole patch (an eyepatch or black paper with only a pinhole in the center)
in front of your eye may also help, since it confines the image to the center of
the eye, and there are fewer ways it can get distorted. (The lens, the cornea
itself, is far from regular in most people. The latest technology literally
draws topographic maps of both surfaces--and they don't form neat bull'seye
images!)
