Was: Transit of the sun. RE: SAFE SOLAR VIEWING

From: DJLaszlo@aol.com
Date: Sun Apr 21 2002 - 14:24:47 EDT

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    In a message dated 4/20/02 1:52:22 PM Mountain Daylight Time, 
    rmcconahy@earthlink.net writes:
    
    << About 30 minutes before the transit I set off with a Meade ETX-90 telescope
     with a doubled-over piece of silverized Mylar over the front for a solar
     filter . . .  One other problem was that the sun was
     still a little too bright in the scope, but I solved that problem by making
     a poor-man's neutral density filter by holding a pair of clip-on sunglasses
     between my eye and the ocular. >>
    
    Ralph --
    
    I got chills reading this.  I hope no one else attempts to watch a solar 
    transit with a homebrew Mylar filter like this.  Your eye is telling you 
    something, I think, if there is too much light to view in comfort.  Even if 
    you are comfortable with a homemade filter, you can damage your eye and feel 
    no pain, if IR and UV are excessive, as they easily could have been.  
    
    Eyepiece mounted solar filters, exposed photographic film, smoked glass, 
    pieces of compact disk, foil-coated wrappers: all are inappropriate in a 
    solar telescope.
    
    Please spend the nominal $ to obtain a safe solar filter with a securely 
    attached cell, and spare yourself the risk of of a scotoma in the middle of 
    your visual field.
    
    Baader Astro-Solar film is inexpensive, available in sheets or mounted, and 
    gives a solar image markedly superior to typical glass and Mylar filters.  My 
    view of sunspot detail and solar granulation markedly improved when I 
    switched to the Baader film from a US-made glass unit.  The sharpness and 
    contrast are much better, and the color is neutral.
    
    In the US, it can be obtained from Astro-Physics;  Jim Kendrick in Canada 
    supplies it in cells.  Perhaps Markus Ludes carries it Germany, or can 
    recommend a source.
    
    Dan Laszlo
    Fort Collins CO
    
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