Glenn Chaple's Observing Basics: Screw-in solar filter hazards
January 2010: Readers provide firsthand evidence that these filters crack under the Sun's heat.
November 23, 2009
Last July, I asked readers to help me document the risk of using solar filters that screw into the eyepiece. For decades I crusaded against screw-ins, warning people to avoid them at all cost. Yet I never heard of one actually failing, so I began to wonder if I might be passing along an urban (or, in this case, cosmic) legend. I wanted firsthand evidence.
This screw-in solar filter cracked while Dennis O’Connell was turned away from the eyepiece of his secondhand 60-millimeter refractor some 40 years ago.
Photo by Dennis O’Connell
You are currently not logged in. This article is only available to Astronomy magazine subscribers.
Already a subscriber to Astronomy magazine?
If you are already a subscriber to Astronomy magazine you must log into your account to view this article. If you do not have an account you will
need to regsiter for one. Registration is FREE and only takes a couple minutes.
Non-subscribers, Subscribe TODAY and save!
Get instant access to subscriber content on Astronomy.com!
- Access our interactive Atlas of the Stars
- Get full access to StarDome PLUS
- Columnist articles
- Search and view our equipment review archive
- Receive full access to our Ask Astro answers
- BONUS web extras not included in the magazine
- Much more!