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.
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.
