On 06 Feb 2009, at 14:49, Chuck Hards wrote:
That's the nice thing about "old school" methods. In a Newtonian, you can remove the mirror from the telescope, and submerge it in tepid water. Soaking it for a while loosens up surface contaminates and most can then be washed away without actually touching the surface. Worst case, a little tender cotton-ball action takes care of the stubborn stuff, but even then there is a "lifting" technique you need to learn to minimize abrasion.
Tough to do with a SCT or Mak corrector on a commercial scope. Or a Newtonian mirror glued to it's wooden cell, lol.
A while back I sent my OTA to Celestron to have it converted to a Fastar-14 (that's where the secondary is made removable and a bracket and lens put in its place that hold a camera making it a very fast f/2 imaging system). It never did work. And to Celestron's credit they didn't charge me anything, let me keep the parts and quit offering retrofits. However, the fact that I now have a removable secondary makes it a fairly straightforward process to clean the corrector plate. I just remove the secondary and put it away and then remove the corrector plate and soak it in warm sudsy water. That gets rid of most of the dirt but, as Chuck notes, a little light work with a cotton ball gets the rest. After rinsing I hold it vertically and spray it with a 50/50 mix of distilled water and Everclear and set it aside to dry. patrick