Test for Solar Filter

[Passerby-B]

Is there any simple test(s) that could be carried out at home to varify the density of solar filter sheets? It could be disastrous if there is one mix up during the supply chain of the sheets.

[TONGKW]

I think you are referring to the two types of Baader solar film of density 3.8 and 5. I believe the density 3.8 Baader solar film is used for photographing the sun in the old days using photographic films. The density 5 Baader solar film can be used for viewing as well as photographing the sun with nowaday’s digital cameras.
Proving it is not defective (cracked or with too many pin holes),it is not really harmful if using the density 3.8 Baader solar film for viewing the sun, the view would just be too bright but this excessive brightness can be toned down to a comfortable level by polarizing filter or neutral density filter. A safe and comfortable level of brightness for viewing the sun is a reduction of 100,000:1, which is equivalent to density 5.
The easiest way to find out is to do a side by side comparison under the sun.

[observer]

I think you are referring to the two types of Baader solar film of density 3.8 and 5. I believe the density 3.8 Baader solar film is used for photographing the sun in the old days using photographic films. The density 5 Baader solar film can be used for viewing as well as photographing the sun with nowaday’s digital cameras.
Proving it is not defective (cracked or with too many pin holes),it is not really harmful if using the density 3.8 Baader solar film for viewing the sun, the view would just be too bright but this excessive brightness can be toned down to a comfortable level by polarizing filter or neutral density filter. A safe and comfortable level of brightness for viewing the sun is a reduction of 100,000:1, which is equivalent to density 5.
The easiest way to find out is to do a side by side comparison under the sun.

用 3.8 目視是有害的!

http://www.agenaastro.com/Baader-AstroS ... bp-bfp.htm

"The photo film listed on this page CANNOT be used for ANY visual work - not even briefly to focus the Sun through your camera. "

[Passerby-B]

Making 5 solar filter holders on Saturday. They created smog clouding over my head
The photographic filter was tested this noon and it should be a 5.0 density. The exposure was 1/1000 sec at F8 with ISO100.