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Old 2021-06-10, 17:15   #34
Uncwilly
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Quote:
Originally Posted by Viliam Furik View Post
I watched it too, with homemade eclipse glasses,
This is how people damage their vision.
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Old 2021-06-10, 17:26   #35
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Quote:
Originally Posted by Uncwilly View Post
This is how people damage their vision.
Open air carbon arcs are pretty effective at close range too. (center electrodes from 2 dead zinc dry cells, on a 110v AC power cord; do not try this at home or elsewhere, alone, or without proper ventilation and protective gear. Or at all.)

Last fiddled with by kriesel on 2021-06-10 at 17:27
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Old 2021-06-10, 17:47   #36
chalsall
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Quote:
Originally Posted by Uncwilly View Post
This is how people damage their vision.
LOL... I was wondering who was going to bat that ball first!

Hand-held pin-hole cameras are taught in elementary school.

And yet a certain POTUS looked at an eclipse without any eye protection recently (fortunately it was cloudy at the time; the US.SS security detail didn't fully understand the risk profile)...
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Old 2021-06-10, 18:03   #37
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Quote:
Originally Posted by Uncwilly View Post
This is how people damage their vision.
In my defense, they are very efficient. The sunlight going through was dimmer than my monitor's light, and I have measured the UV-B light coming through to be about 0% (our school physics teacher has a device for measuring UV-B radiation.). Measurement was done using real sunlight on a two-layer version in March, I think, so three layers should be plenty for June. They seem to only let through a bit of red-to-yellow mix because the sun looked orange through them.
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Old 2021-06-10, 18:16   #38
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Quote:
Originally Posted by Viliam Furik View Post
I have measured the UV-B light coming through to be about 0% (our school physics teacher has a device for measuring UV-B radiation.)
0% of what? Don't you know that 0% (0.4% rounded) of the radiation inside the containment at Chernobyl is still bad for you? For reference the Sun's apparent magnitude is −26.7, that of the full Moon is about −11, and that of the bright star Sirius, −1.5. And that is a log scale. -23 will still hurt you.
And the UV-A, C, and IR values? The IR is just one part that will get you.
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Old 2021-06-10, 18:48   #39
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Nice shots from Pittsburgh on twitter.
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Old 2021-06-10, 18:55   #40
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Quote:
Originally Posted by Uncwilly View Post
0% of what?

And the UV-A, C, and IR values? The IR is just one part that will get you.
About 0% of sunlight's UV-B, as I mentioned. For other UVs, I don't think the amount is much different. About IR, I don't think it can stop it, but neither can many things. For exposure as short as taking a look at an eclipse, I think even if I looked directly I would be ok after few minutes of seeing one big blur.
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Old 2021-06-10, 19:30   #41
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1/4000 f/36 through cloud, after a short drive to get a bit south of Cambridge where the cloud cover was less complete:

https://www.chiark.greenend.org.uk/~twomack/eclipse.jpg

Last fiddled with by fivemack on 2021-06-10 at 19:33
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Old 2021-06-11, 08:11   #42
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Quote:
Originally Posted by fivemack View Post
1/4000 f/36 through cloud, after a short drive to get a bit south of Cambridge where the cloud cover was less complete:
A great shot!
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Old 2021-06-12, 08:01   #43
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Courtesy of Astronomy Picture of the Day

https://apod.nasa.gov/apod/archivepix.html

Enjoy
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