did you make it yourself or is it designed for photographic use?
It's originally a telescope accessory, designed for watching the sun. http://anders.hultman.nu/kamera/solfilter.jpeg
Pieter Nagel:
I think a 20 stop filter would be dangerous to use for solar photgraphy. It might block 20 stops of visible light, but let through enough other wavelengths to fry your eye through the viewfinder. Even if you can't see the sun at all.
Yes, probably. Focused sunlight is a dangerous thing indeed. I have a friend who accidentally burned a hole in his camera shutter while setting up his gear for a sun shot.
I once was given a piece of solar filter that looked just like very thin aluminium foil. It was a sheet of metal manufactured so thin that it became transparent enough for solar viewing. The image through this was noticably whiter than through another Mylar (?) filter, whose image was more muddy and yellow.
The filter I have looks just like aluminium foil and it gives a blueish colour.
Unfortunately, I do not remember the make. I suggest you ask at a place that sells telescopes.
My filter is from such a place, but your tip is useful anyway: Thinking about it now, I might find a better filter by looking again. I was in quite a hurry when I bought it, since the eclipse I planned to shoot was imminent, and I had to settle for what they had in stock.
anders ------------------------- http://anders.hultman.nu/
