I have been told by several opticians only clean if you absolutely have to. The micro scratches that can result from aggressive cleaning can cause more optical degradation than dust and film on the surface of the optic. -----Original Message----- From: utah-astronomy-bounces@mailman.xmission.com [mailto:utah-astronomy-bounces@mailman.xmission.com] On Behalf Of Rodger C. Fry Sent: Friday, February 06, 2009 1:56 PM To: Utah Astronomy Subject: Re: [Utah-astronomy] Frosty the Telescope Joe, Let me know how you clean your corrector plate and how it comes out. My 10" is three years old and I have yet to clean it but someday I will need to. With the UHTC coating I am hesitant to do anything. Good Luck in cleaning this. Rodger Fry ----- Original Message ----- From: "Joe Bauman" <josephmbauman@yahoo.com> To: "Utah Astronomy" <utah-astronomy@mailman.xmission.com> Sent: Friday, February 06, 2009 1:29 PM Subject: Re: [Utah-astronomy] Frosty the Telescope Take a look at it close up: http://www.slas.us/gallery2/main.php?g2_itemId=968&g2_imageViewsIndex=1 -- Best wishes, Joe --- On Fri, 2/6/09, Canopus56 <canopus56@yahoo.com> wrote: From: Canopus56 <canopus56@yahoo.com> Subject: [Utah-astronomy] Frosty the Telescope To: "Utah Astronomy List Serv" <utah-astronomy@mailman.xmission.com> Date: Friday, February 6, 2009, 1:11 PM That's one frosty corrector plate. I've never seen anything like it! - Kurt http://deseretnews.com/media/images/blog/10000030-1233936496.jpg _______________________________________________ Utah-Astronomy mailing list Utah-Astronomy@mailman.xmission.com http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Visit the Photo Gallery: http://gallery.utahastronomy.com Visit the Wiki: http://www.utahastronomy.com _______________________________________________ Utah-Astronomy mailing list Utah-Astronomy@mailman.xmission.com http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Visit the Photo Gallery: http://gallery.utahastronomy.com Visit the Wiki: http://www.utahastronomy.com _______________________________________________ Utah-Astronomy mailing list Utah-Astronomy@mailman.xmission.com http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Visit the Photo Gallery: http://gallery.utahastronomy.com Visit the Wiki: http://www.utahastronomy.com

PS: I felt I had to clean it because the glass was covered with the kind of marks that dirty rain leaves on a car's window. And I mean covered. -- Joe --- On Fri, 2/6/09, Rodger C. Fry <rcfry@comcast.net> wrote: From: Rodger C. Fry <rcfry@comcast.net> Subject: Re: [Utah-astronomy] Frosty the Telescope To: "Utah Astronomy" <utah-astronomy@mailman.xmission.com> Date: Friday, February 6, 2009, 2:40 PM Don, Thanks for the info. This is exactly what my feeling is. Thanks Rodger ----- Original Message ----- From: "Don J. Colton" <djcolton@piol.com> To: "'Utah Astronomy'" <utah-astronomy@mailman.xmission.com> Sent: Friday, February 06, 2009 2:17 PM Subject: Re: [Utah-astronomy] Frosty the Telescope

I have been told by several opticians only clean if you absolutely have to. The micro scratches that can result from aggressive cleaning can cause more optical degradation than dust and film on the surface of the optic.

-----Original Message----- From: utah-astronomy-bounces@mailman.xmission.com [mailto:utah-astronomy-bounces@mailman.xmission.com] On Behalf Of Rodger C. Fry Sent: Friday, February 06, 2009 1:56 PM To: Utah Astronomy Subject: Re: [Utah-astronomy] Frosty the Telescope

Joe, Let me know how you clean your corrector plate and how it comes out. My 10" is three years old and I have yet to clean it but someday I will need

to. With the UHTC coating I am hesitant to do anything.

Good Luck in cleaning this.

Rodger Fry ----- Original Message ----- From: "Joe Bauman" <josephmbauman@yahoo.com> To: "Utah Astronomy" <utah-astronomy@mailman.xmission.com> Sent: Friday, February 06, 2009 1:29 PM Subject: Re: [Utah-astronomy] Frosty the Telescope

Take a look at it close up:

http://www.slas.us/gallery2/main.php?g2_itemId=968&g2_imageViewsIndex=1

-- Best wishes, Joe

--- On Fri, 2/6/09, Canopus56 <canopus56@yahoo.com> wrote: From: Canopus56 <canopus56@yahoo.com> Subject: [Utah-astronomy] Frosty the Telescope To: "Utah Astronomy List Serv" <utah-astronomy@mailman.xmission.com> Date: Friday, February 6, 2009, 1:11 PM

That's one frosty corrector plate. I've never seen anything like it! - Kurt

http://deseretnews.com/media/images/blog/10000030-1233936496.jpg

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Hi all, I did clean it, but I was exceptionally careful and did not detect any scratches, even  using my magnifying glass. After the plate was dry I used a camel-hair brush and a soft t-shirt to git rid of grit, brushing very lightly. Then I cleaned the with something called Shield Lens Cleaner, a set of pre-moistened towelettes. They are advertised for "scopes, binoculars, cameras." Whether I actually did harm the optics I won't know until I use the telescope again, but I feel pretty good about it. I can't see any damage to coating or glass. Thanks, Joe --- On Fri, 2/6/09, Don J. Colton <djcolton@piol.com> wrote: From: Don J. Colton <djcolton@piol.com> Subject: Re: [Utah-astronomy] Frosty the Telescope To: "'Utah Astronomy'" <utah-astronomy@mailman.xmission.com> Date: Friday, February 6, 2009, 2:17 PM I have been told by several opticians only clean if you absolutely have to. The micro scratches that can result from aggressive cleaning can cause more optical degradation than dust and film on the surface of the optic. -----Original Message----- From: utah-astronomy-bounces@mailman.xmission.com [mailto:utah-astronomy-bounces@mailman.xmission.com] On Behalf Of Rodger C. Fry Sent: Friday, February 06, 2009 1:56 PM To: Utah Astronomy Subject: Re: [Utah-astronomy] Frosty the Telescope Joe, Let me know how you clean your corrector plate and how it comes out. My 10" is three years old and I have yet to clean it but someday I will need to. With the UHTC coating I am hesitant to do anything. Good Luck in cleaning this. Rodger Fry ----- Original Message ----- From: "Joe Bauman" <josephmbauman@yahoo.com> To: "Utah Astronomy" <utah-astronomy@mailman.xmission.com> Sent: Friday, February 06, 2009 1:29 PM Subject: Re: [Utah-astronomy] Frosty the Telescope Take a look at it close up: http://www.slas.us/gallery2/main.php?g2_itemId=968&g2_imageViewsIndex=1 -- Best wishes, Joe --- On Fri, 2/6/09, Canopus56 <canopus56@yahoo.com> wrote: From: Canopus56 <canopus56@yahoo.com> Subject: [Utah-astronomy] Frosty the Telescope To: "Utah Astronomy List Serv" <utah-astronomy@mailman.xmission.com> Date: Friday, February 6, 2009, 1:11 PM That's one frosty corrector plate. I've never seen anything like it! - Kurt http://deseretnews.com/media/images/blog/10000030-1233936496.jpg _______________________________________________ Utah-Astronomy mailing list Utah-Astronomy@mailman.xmission.com http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Visit the Photo Gallery: http://gallery.utahastronomy.com Visit the Wiki: http://www.utahastronomy.com _______________________________________________ Utah-Astronomy mailing list Utah-Astronomy@mailman.xmission.com http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Visit the Photo Gallery: http://gallery.utahastronomy.com Visit the Wiki: http://www.utahastronomy.com _______________________________________________ Utah-Astronomy mailing list Utah-Astronomy@mailman.xmission.com http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Visit the Photo Gallery: http://gallery.utahastronomy.com Visit the Wiki: http://www.utahastronomy.com _______________________________________________ Utah-Astronomy mailing list Utah-Astronomy@mailman.xmission.com http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Visit the Photo Gallery: http://gallery.utahastronomy.com Visit the Wiki: http://www.utahastronomy.com

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