Cloudy weather prevented an outdoor observing session (RACOBS), so a dozen members & guests attended an informal meeting at the Museum. The evening’s roundtable topic was ‘cleaning optics’. Following on the theme of the previous weekend’s optics cleaning session at NCSU, techniques were shared for cleaning eyepieces, mirrors and Schmidt-Cassegrain corrector plates.
First, Phyllis Lang demonstrated Jim Pressley’s technique for cleaning eyepieces. In just 10 minutes, Mark Lang’s dirty 25 mm Celestron Erfle became a clean, happy Erfle. Jim’s method depended on cotton swabs (i.e., Q-tips), acetone and a lens cleaner named Residual Oil Remover (ROR).
Next, Pat Moore described his method of cleaning mirrors. On his 16 inch mirror, he used nothing more exotic than a garden hose, Dawn dish liquid, distilled water and sterile cotton batting. He recommended NOT using any isopropyl alcohol as it could damage the aluminum coating if there were any holes in the overcoatings.
Lastly, Mark Lang discussed removing and cleaning the corrector plate on a Schmidt-Cassegrain telescope. His technique was the same as Jim Pressley’s method for eyepieces.
This technique was employed during last weekend’s cleaning session at NCSU on several C-8 telescopes used in the astronomy lab classes. These correctors had dirt, oils and mold, all of which responded very well to cleaning. Mark mentioned the importance of marking the position of the corrector before removing it from the tube assembly so that it could be reinstalled after cleaning in exactly the same position.
– Phyllis Lang
