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Old 21-08-2017, 05:21   #1
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Eclipse Viewing with a Sextant

For those located in an area of the US that will be within a portion of the umbra of the Eclipse today, one's Sextant gives one a good instrument for viewing the event. The Sextant's selectable shades are designed to deal with the intensity of solar viewing and the telescope will allow one a good view of the Sun's outer atmosphere/corona. It should be interesting.
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Old 21-08-2017, 09:11   #2
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Re: Eclipse Viewing with a Sextant

Took mine to work with me.
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Old 22-08-2017, 07:14   #3
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Re: Eclipse Viewing with a Sextant

Well--The "Experiment" worked pretty well here in southwest Florida although the altitude of the sun at the time of the eclipse was pretty high so it was a tad difficult to maintain the image. Fortunately, the azimuth put the reflected image of the sun, though our whole horizon" glass, opposite my neighbors garage wall which was somewhat shaded so the image was pretty clear. What surprised me was the fact that although, from here, 80% of the sun was occluded, the brightness of the day did not seem to decrease appreciably although I learned somewhat later that local air temps dropped by 3º during the event. The event did have an effect on the animals, however, because, as the shading progressed, our dog seemed to be under the impression that it was her dinner time!

FWIW...
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Old 23-08-2017, 10:59   #4
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Re: Eclipse Viewing with a Sextant

With the recent eclipse there has been a ton of information about how to safely view the sun, such as using a #14 welders glass. And also how damaging the sun can be to your eyes. So my Sextant has 3 or 4 filters to move in front of the lens and mirror. But there are no instructions about the density of these filters or how to use them. How do I know that I am not damaging my eyes while taking a sun sight? Has anyone come across some instructions on how to properly use the sun filters on a sextant?
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Old 24-08-2017, 11:54   #5
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Re: Eclipse Viewing with a Sextant

We made the drive to the lake, and then the 20 mile (chip shot for most of you) boat ride to get into the path of totality. My daughter was pretty excited about it, but I didn't buy into the hype. Boy was I wrong. That was one of the neatest experiences I've had. I wasn't satisfied with a #14 shade, so I taped #10's over #8's for the whole family. The photo of the partial was taken with my phone through that welding hood setup. The photo of the engagement ring and the total eclipse are pictures of my laptop screen (sorry, I'll work on some quality stills) from a video I shot with no filter. Obviously, the gear was thoroughly tested. lol Click image for larger version

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Old 24-08-2017, 11:55   #6
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Re: Eclipse Viewing with a Sextant

Sideways pics.
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Old 24-08-2017, 12:23   #7
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Re: Eclipse Viewing with a Sextant

Quote:
Originally Posted by AaronT View Post
With the recent eclipse there has been a ton of information about how to safely view the sun, such as using a #14 welders glass. And also how damaging the sun can be to your eyes. So my Sextant has 3 or 4 filters to move in front of the lens and mirror. But there are no instructions about the density of these filters or how to use them. How do I know that I am not damaging my eyes while taking a sun sight? Has anyone come across some instructions on how to properly use the sun filters on a sextant?
Yes, I've wondered the same thing myself.
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Old 24-08-2017, 12:45   #8
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Re: Eclipse Viewing with a Sextant

I would use a systematic appraoch:
1. Put on all filters and watch the sun.
2. If no view, remove weakest/lightest filter.
3. If no view, put back filter of step 2, remove 2nd weakest filter.
4. If no view, repeat step 2 and 3
5. etc

Maybe labourious, but you don't put your eyes at risk
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Old 24-08-2017, 13:23   #9
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Re: Eclipse Viewing with a Sextant

This should not be taken as proper advice, but I do have quite a bit of experience under a welding hood. If you glance at the sun with a filter, and have any spots in your vision when you look away, I would assume that you need a "darker" filter. Also, I read that using a magnifying device will amplify the possible UV damage to your eyes.....Something to the effect of looking at the LCD screen and not the viewfinder while videoing type of thing. For the record, I did glance at the sun with a #8, #10, and a #14 welding shade. No immediate discomfort with the #14, but I could instantly tell that the #8 and #10 were a no go.
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Old 24-08-2017, 13:59   #10
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Re: Eclipse Viewing with a Sextant

Jealous of you guys, I remember as a small boy a total eclipse, we must have been in an area close to the total path and I remember it went dusk dark in the middle of the afternoon.

We had a partial a few years back and you could hardly tell.
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Old 24-08-2017, 16:53   #11
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Re: Eclipse Viewing with a Sextant

I would think that part of the problem is that eye (or skin) damage isn't caused by just visible frequencies of light alone. So that you could have a filter that "feels" sufficiently protective, but that is still allowing wavelengths of light in the UV & IR spectrums to reach your eye(s) & cause damage.
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Old 24-08-2017, 18:22   #12
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Re: Eclipse Viewing with a Sextant

Quote:
Originally Posted by AaronT View Post
With the recent eclipse there has been a ton of information about how to safely view the sun, such as using a #14 welders glass. And also how damaging the sun can be to your eyes. So my Sextant has 3 or 4 filters to move in front of the lens and mirror. But there are no instructions about the density of these filters or how to use them. How do I know that I am not damaging my eyes while taking a sun sight? Has anyone come across some instructions on how to properly use the sun filters on a sextant?
Properly used, the filters will so dim the sun that you need not fear eye damage. I filter until the image of the sun is crisp and round and dim with no corona. Remove one filter, and the edge gets impossible to see clearly, and thus impossible to precisely put on the horizon.
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Old 29-08-2017, 06:07   #13
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Re: Eclipse Viewing with a Sextant

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Originally Posted by Benz View Post
Properly used, the filters will so dim the sun that you need not fear eye damage. I filter until the image of the sun is crisp and round and dim with no corona. Remove one filter, and the edge gets impossible to see clearly, and thus impossible to precisely put on the horizon.
Thanks for that explanation Benz. That makes sense.

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