Watching an eclipse
On Mon, 21 Aug 2017 22:24:13 +0100, Andy Burns
I've watched two through (arc) welding filters.
Quite a chunk of the ISO/BS standard is lifted from section 4.1 of this
exposed B&W film provided you know it's a silver-based film
I was going to ask if such safe methods existed in the 1960s then I
realised there was probably more welding (in the UK) and more
monochorme film in these days :-)