Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Path: utzoo!mnetor!seismo!columbia!rutgers!ll-xn!mit-eddie!genrad!decvax!tektronix!orca!tekecs!star!markm
From: markm@star.UUCP
Newsgroups: sci.astro
Subject: Re: Solar filters
Message-ID: <7791@tekecs.TEK.COM>
Date: Tue, 21-Oct-86 15:32:21 EDT
Article-I.D.: tekecs.7791
Posted: Tue Oct 21 15:32:21 1986
Date-Received: Wed, 22-Oct-86 22:30:17 EDT
References: <779@ur-tut.UUCP>
Sender: news@tekecs.TEK.COM
Reply-To: markm@star.UUCP (Mark Mehall)
Organization: Tektronix, Inc., Wilsonville, OR
Lines: 36
Summary: Safe Solar Filters

In article <779@ur-tut.UUCP> lutz@ur-tut.UUCP (Dave Lutz) writes:
>   A few people said that there was an article in Sky and Telescope
> concerning the issue of solar filters and viewing the sun.  It is
>supposed to be a very good article and it even deals with the question
>of using welders glass for this purpose.  I'm sorry to say that none
>of them could remember what issue it was in.  
>
The article is "Safe Solar Filters" by B. Ralph Chou, School of Optometry,
Univ. of Waterloo, Ontario.  It was published in the August, 1981 issue
of SKY AND TELESCOPE.  The author states "...that metal-coated glass or
Mylar filters are safe for visual and photographic work.  Properly
treated black-and-white film is safe when two layers are used.  And
welder's glass shade No. 14 is also safe for visual use but it is
not uniform enough for use over a telescope objective, and such a filter
may crack if placed at the eye end.  Less dense shades (lower numbers)
are not suitable for direct solar observing.  Under no circumstances
should color film, smoked glass, or gelatin neutral-density filters be
used for direct solar observation."

Roger W. Tuthill, Inc. will send a copy of the article with their product
literature (they sell the "Solar Skreen", a mylar sun filter), if you
send them a stamped ($1.24 U.S.), self addressed, large envelope. The
address is 11 Tanglewood Lane, Mountainside, New Jersey 07092.  Another
company to contact is Thousand Oaks Optical, Box 314, Wyandotte, Michigan
48192.  They sell both mylar and metal-coated glass filters in a variety
of sizes.


Explicit Disclaimers:  I am speaking for myself, not Tektronix.
		       I am not affiliated with any of the companies
			mentioned in this article.
Mark Mehall			uucp:	{ucbvax,decvax,ihnp4}!
Tektronix Inc.				tektronix!tekecs!markm
P.O. Box 1000  60-770		CSnet:	tekecs!markm@tek
Wilsonville, Oregon 97070	ARPAnet: tekecs!markm.tek@csnet-relay
Phone (503) 685-2275		FAX: (503) 682-3408 GRP III, II Auto