Observing Basics web extra: Tales of screw-in solar filters

The dangers of these accessories cracking from the Sun's heat proved to be more than just a cosmic legend.

Contributed by Glenn Chaple

Published: November 23, 2009

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

Last July, I asked for reader input to help me document the risk of using solar filters that screw into the eyepiece. They commonly accessorized low-budget telescopes made in the 1960s and 1970s — mostly 2.4-inch (60 millimeters) refractors and 4.5-inch (114mm) reflectors, the latter stopped down with 2-inch (50mm) aperture reducers. Here are the e-mail responses I received.

Subscriber-Only Content

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!

	Sun	Sun	Moon
RISE	—		—	PHASE	—
SET	—		—	DISK	—

	Mercury	Mercury	Venus	Venus
RISE	—		—
SET	—		—
		—		—