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Solar Eclipse 2017 Countdown: 500 days from today, a total solar eclipse will be seen across the entire breadth of the continental United States for the first time in nearly a century. (xpost from /r/solareclipse)(r/space)
If you plan on viewing this, order your equipment now. Once you get to within about 3-4 months of the eclipse, viewing equipment is very hard to find, even through online retailers.
In particular, No. 14 (or darker) welder’s glass is great for viewing. Buy some generic welders goggles with 50mm round lenses. Those lenses are typically No. 5 glass. Order two replacement lenses of No. 14 glass. Then just unscrew the lenscaps on the goggles and replace the stock No. 5 lenses with the No. 14 lenses. You can get the goggles and two No. 14 lenses on Amazon for about $20 shipped with Prime.
Edit: To all those asking, here are links to goggles and lenses. These are the goggle and lenses I bought. The goggles have screw-off caps, so the lenses are easily replaceable. You must order 2 replacement lenses, as the price is just for a single lens. This goggle/lens combo is under $20 (though you have to spend $25 total to get free shipping on those lenses, so buy a book or something). I make no money off either of these. Also note, No. 14 lenses are very dark. You can’t really see much but the sun when you have them on. You can easily see the difference between the No. 5 lenses that come with the goggles (which tint about as much as sunglasses) vs. the No. 14 lenses you buy separately (which are dark as night unless staring directly at a bright light or the sun).
~~Lenses (order two): www.amazon.com/50mm-Circular-Welding-Green-Shade/d…
Lenses are out stock at Amazon. You can buy the same 50mm round lenses here: www.phillips-safety.com/welding-safety/green-weldi… Make sure you get Green Shade 14. You will need two of them.
A lot of people have asked me about different kind of eclipse viewers, such as the ones below. If you get those, at a minimum make sure they are ISO certified. The reason I wouldn’t recommend something like those is because, while the lens materials may be certified, the design of the glasses is not. Those glasses (depending on the design) may let in a lot of light around their periphery. Remember: you are using these to stare at the sun, so it’s not something you want to fuck around with. You can’t un-damage your eyes. I like the welding goggles because they fully enclose your eyes and block all light from getting in on the periphery.
Here are some ISO certified (lens) eclipse viewers. As noted above, I don’t recommend these type of devices for eclipses.
2nd Edit: Well, you all gave those lenses the reddit hug of death and they are now out of stock. As an alternative, you can use a rectangular set of goggles and lens.