On 8/7/2012 12:46 PM, Beloved Leader wrote:

Thanks for the information. When I observed the transit of Venus back
in June, I used a really dark piece of glass from a welder's mask.
Whatever the number was, it was dark enough that I could not see
surrounding terrain.

Humph! Even an 8 or 10 is "dark enough that I could not see surrounding
terrain."...but that is not a high enough number.

The recommended number is #14...and they are additive if you can't find
a 14.

For the recent transit, my welding supply shop did not have a #14 but
they did have a #10 and #4, which I taped together.

Additional note: Put the #14 glass in FRONT (input side) of your
binoculars. If you put it on the output side, the concentrated heat
could leave you with a face full of shattered glass.