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Annular solar eclipse on 20 May 2012

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  • Annular solar eclipse on 20 May 2012

    We have had a discussion of this subject here http://bbs.homeshopmachinist.net/sho...nnular+eclipse, but the title of that thread is no longer pertinent.

    Ctein advises using a 3.0 ND filter for viewing it, or a totally fogged strip of 35mm film.

    http://theonlinephotographer.typepad...y-20-2012.html
    Allan Ostling

    Phoenix, Arizona

  • #2
    I disagree with the advice to use fogged film. It isn't safe with most current film. The only fogged 35mm film that is safe to use is black/white film since it is the silver that provides the protection. Even then Ilford black/white isn't safe because it is a dye process. Colour films have no silver remaining after developing. A strip of fogged colour film will look and seem like sufficient protection but the IR transmission just below the visible spectrum is about 90%. It is not suitable.
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    • #3
      It's good that you noted this. I mis-characterized what Ctein stated in his article:
      For just viewing, fully-fogged B&W silver film is safe

      I once would have to look no further than the waste basket in my darkroom for a strip of B&W film. Now, I might get a 3.0 ND filter (for which I can find other uses).
      Allan Ostling

      Phoenix, Arizona

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