NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Eye problems and IE, IC
From: Bill Noyce
Date: 2006 Jul 12, 16:08 -0500
One of the questions someone asked in trying to diagnose Bill's
varying IE measurements was "does the position of the tangency
vary" between left & right eyes, or between horizontal and vertical
orientations. Bill interpreted that as questioning whether the
tangency was actually touching, or had some overlap or gap, but
I interpreted the question differently.
Are all the measurements being made with the objects brought to
tangency *in the center of the optical field*, rather than off to one
side or the other, or toward the higher or lower part? To a first order
it should not matter, but if the mirrors are not perfectly flat then it
makes a difference, and I think side error might also vary across the
optical field.
Like George, I have a hard time understanding how anything in the
optical path after the horizon mirror can change whether the two
images seem to be touching. If they appear to be touching, then
they emerge from the horizon mirror in parallel. What then can
separate them? Even flaws in telescope or eyes should not be
able to do that -- at least if the horizon mirror and index mirror are
flat.
-- Bill N. 42d 44' N 72d 24' W
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To post to this group, send email to NavList@fer3.com
To , send email to NavList-@fer3.com
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From: Bill Noyce
Date: 2006 Jul 12, 16:08 -0500
One of the questions someone asked in trying to diagnose Bill's
varying IE measurements was "does the position of the tangency
vary" between left & right eyes, or between horizontal and vertical
orientations. Bill interpreted that as questioning whether the
tangency was actually touching, or had some overlap or gap, but
I interpreted the question differently.
Are all the measurements being made with the objects brought to
tangency *in the center of the optical field*, rather than off to one
side or the other, or toward the higher or lower part? To a first order
it should not matter, but if the mirrors are not perfectly flat then it
makes a difference, and I think side error might also vary across the
optical field.
Like George, I have a hard time understanding how anything in the
optical path after the horizon mirror can change whether the two
images seem to be touching. If they appear to be touching, then
they emerge from the horizon mirror in parallel. What then can
separate them? Even flaws in telescope or eyes should not be
able to do that -- at least if the horizon mirror and index mirror are
flat.
-- Bill N. 42d 44' N 72d 24' W
--~--~---------~--~----~------------~-------~--~----~
To post to this group, send email to NavList@fer3.com
To , send email to NavList-@fer3.com
-~----------~----~----~----~------~----~------~--~---
