Danger Will Robinson. Make sure that you get a specific solar filter. Neutral density is only defined over the visual spectrum so can let through IR and UV. Also, I couldn't find anything over 4.0, and I've always seen 5.0 OD is the minimum for direct observation of the sun and probably more if you are looking through any lens. (remember, always filter the input of the camera/telescope/binoculars not the output)
Now where have I hidden my welding goggles. I don't want to have to buy another pair today.
