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I know it is not safe when viewing a solar eclipse to look directly at the sun. I know you can purchase solar eclipse glasses online but how do you make your own solar eclipse glasses that are safe to use for solar eclipse viewing (and let us throw in the transit of Venus)?

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Shopping recommendation are off-topic for the site, so I stripped out the last sentence. I don't know how much expertise we have, but the rest is a good question. –  dmckee May 16 '12 at 19:15
    
@dmckee - That is fine, I would of asked this on the Astronomy SE Site but unfortunately that was shut down, hope someone can help here. => –  Lynda May 16 '12 at 19:45
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Most of Astro.SE was migrated here, and this is the right place to ask in the post-Astro.SE era. However, I don't know how many of the regulars from astro are visiting this site consistently. –  dmckee May 16 '12 at 19:47

3 Answers 3

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Making your own eyewear for direct viewing of the sun is probably not too practical. You essentially need a filter that blocks well over 99% of the incoming light. You can use #14 or #16 welder's goggles for this, or obtain specialized filters designed for this purpose. These filters are a glass substrate with a metal deposition layer on them that is designed to transmit only a small fraction of the light.

As an alternative to direct viewing, it is much easier to make a system for projection viewing of the sun. In this case, you would create a projected image of the sun on a surface, and observe the image. You can look up "solar pinhole viewer" or check out these instructions for details on how to put together a simple solar viewing system with stuff you may have around the house (cardboard, paper and aluminum foil): http://www.exploratorium.edu/eclipse/how.html

For more on observing the sun, see this article: http://www.skyandtelescope.com/observing/objects/sun/Viewing_the_Sun_Safely.html

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A pinhole device is what I used for the partial (total in parts of Mexico) eclipse visible in the south western US in the 90's. Cheep, easy and effective. –  dmckee May 16 '12 at 20:20
    
@dmckee you mean watching the image from a pinhole on an A4 paper? That is what I have used anyway. When I was a child my mother blackened well a piece of glass with soot from a candle.So well you can see nothing through it. The sun shows up. It is also interesting to watch the shadows, particularly of leaves as the eclipse progresses. –  anna v May 20 '12 at 3:38
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@anna: I cut a hole in the end of a shoebox and stretched aluminium foil across it so I could make a set of holes in graded sizes (to optimize the focus/light tradeoff) and projected on a sheet of paper at the other end. –  dmckee May 20 '12 at 3:59

I don't think I would recommend any of the traditional ways of making them - it's too easy to make a mistake and hurt your eyes.

The best way to view an eclipse is with a pinhole camera use telescopes/binoculars to project the image onto a wall.

If you want to look at it directly a piece of welding glass (the screen from a welding mask) is probably the cheapest easiest safest way - you should be able to get it from a car parts / machine store.

edit - just for the lawyers: Welding glass for electric arc welders strongly blocks UV, the wavelengths you have to worry about. Older gas welding masks might not have good UV blocking.

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If you have a camera on your phone point it at the sun and look at the screen. any camera with a screen will do. this way you can take pictures too

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How sure are you that this won't damage your camera? –  Keith Thompson May 20 '12 at 4:43
    
Don't use your camera phone. Yes, it would work for viewing. But it would probably damage the image sensor since it doesn't have the correct lens. –  user9313 May 20 '12 at 6:56

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