Annular Eclipse May 20,2012

[Kayaker72]

Thanks Pat. I have seen that you need Shade No. 14 for solar viewing. I've been looking, but haven't yet found what the basis is for the shade numbers. I actually have ordered some shade number 12 from mcmaster.com, but had trouble finding shade number 14. Most welding glass out there seems to be shade #5-8. So, be careful if using welding glass.

For comparison, the Baader filter/film for photography is rated at ND 3.8 (12 2/3 stops). But when I talked to the people at astro-physics they really emphasized that was for photography only and if there was any chance of me looking through the viewfinder, to use the filter/film rated "visual" which is ND 5.0, so 16 2/3 stops.

I am a complete novice about this, so I am being conservative. But it also seems to be about more than just number of stops and that you have to be very careful about blocking non-visible light, both IR and UV.