On Thursday, May 17, 2012 at 6:29:31 PM UTC-7, Steve B wrote:
"mike" wrote in message
...
I want to look at the eclipse this weekend.
Everybody says a #14 welding shade is good.
I don't have one.

So, how do the numbers stack up when you use 2?
I'm guessing it's not linear, so 7+7 doesn't = 14???

What's the math for stacking welding shades?


Thanks, mike

Sent my wife today for two 4 x 5 shade 14 lenses. They said they were out,
and had sold 14,000 lenses. We are SMACK DAB in the middle of the path here
in Toquerville, Utah. My NexGen only goes up to 13. What's up with that?

Steve

The NASA site says that between 12 and 14 is safe but that some find 12 to bright and other 14 to dark but you can't really get 13. There are a lot of "internet experts" who just run with 14 and spout it as gospel.