NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Looking at the Sun through a telescope
From: Frank Reed CT
Date: 2006 Aug 6, 22:07 -0500
Ken, you wrote:
"Well, I didn't mean to make light of the dangers of looking at the sun
through a telescope on a sextant. However, as someone involved with the
manufacture of sextants, I am aware of the possibility on product liability
litigation in this area. So, I have collected any and all anecdotes and
opinions on the subject in order to arm ourselves for this possibility.
Apart from the scientific discussion of light, lenses and retinas, I am not
aware of any instances of actual eye damage occurring from use of a modern
day sextant (or for that matter, an astronomical telescope). If any list
members know of such things, I would appreciate any leads they may have."
Some of the reports I've read on eclipse blindness suggest that it takes
"minutes" of viewing time to get to the level of permanent damage. But temporary
vision impairment lasting for days or weeks --long enough to be scary, long
enough to require medical attention, and probably long enough to get the
attention of some lawyer-- I do believe that that's a very real possibility when
using a sextant telescope.
The last time this topic was discussed, I couldn't remember where I had read
an account of eye damage from sextant use, but I knew it was out there
somewhere. I found it again last fall when we were discussing the "proper" method
for swinging the arc. It's in Letcher's "Self-Contained Celestial Navigation"
on page 30 (opposite his nice little diagram on swinging the arc). He
recounts a story while cruising off the coast of Mexico in 1970 when he
accidentally flipped all the shades up and looked right at the Sun through the sextant.
He writes: "I suffered severe eyestrain and had a partially blind spot in the
center of my right eye for several months afterward". He saw a doctor months
later who suggested that the visual impairment might get worse, but he adds
"the spot slowly disappeared".
-FER
42.0N 87.7W, or 41.4N 72.1W.
www.HistoricalAtlas.com/lunars
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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: Frank Reed CT
Date: 2006 Aug 6, 22:07 -0500
Ken, you wrote:
"Well, I didn't mean to make light of the dangers of looking at the sun
through a telescope on a sextant. However, as someone involved with the
manufacture of sextants, I am aware of the possibility on product liability
litigation in this area. So, I have collected any and all anecdotes and
opinions on the subject in order to arm ourselves for this possibility.
Apart from the scientific discussion of light, lenses and retinas, I am not
aware of any instances of actual eye damage occurring from use of a modern
day sextant (or for that matter, an astronomical telescope). If any list
members know of such things, I would appreciate any leads they may have."
Some of the reports I've read on eclipse blindness suggest that it takes
"minutes" of viewing time to get to the level of permanent damage. But temporary
vision impairment lasting for days or weeks --long enough to be scary, long
enough to require medical attention, and probably long enough to get the
attention of some lawyer-- I do believe that that's a very real possibility when
using a sextant telescope.
The last time this topic was discussed, I couldn't remember where I had read
an account of eye damage from sextant use, but I knew it was out there
somewhere. I found it again last fall when we were discussing the "proper" method
for swinging the arc. It's in Letcher's "Self-Contained Celestial Navigation"
on page 30 (opposite his nice little diagram on swinging the arc). He
recounts a story while cruising off the coast of Mexico in 1970 when he
accidentally flipped all the shades up and looked right at the Sun through the sextant.
He writes: "I suffered severe eyestrain and had a partially blind spot in the
center of my right eye for several months afterward". He saw a doctor months
later who suggested that the visual impairment might get worse, but he adds
"the spot slowly disappeared".
-FER
42.0N 87.7W, or 41.4N 72.1W.
www.HistoricalAtlas.com/lunars
--~--~---------~--~----~------------~-------~--~----~
To post to this group, send email to NavList@fer3.com
To , send email to NavList-@fer3.com
-~----------~----~----~----~------~----~------~--~---
