C14 Corrector in bad shape! Pls help!!!

[Kodo65]

Hi!

I have the opportunity to buy a C14 OTA. However the corrector seems to have "small silvery spots", "marks of running fluid" now dried, and an attempt to wipe of the dew with "something"... I'm mostly concerned about the silvery spots which seem to be both in/outside of the OTA! Is this a lost case OR can it be restored???

Many thanks in advance!!!

Peter

[PeterCPC]

I recently cleaned the corrector plate on my C9.25 - quite easy to do as long as you are methodical and have the right materials to hand. Give it a go. Nothing ventured...

[Kodo65]

Thanks for your encouraging words! Do you have any clue what the "silvery spots" might be??? It looks almost like small aluminium "lakes"...

[PeterCPC]

Impossible to tell from the photos but I suspect a dried fluid of some sort.

[rrb24]

It doesn't look like fungus which is good news.  As Peter says, correctors are not that difficult to clean if you are methodical and have the (clean) space and materials to do it properly. 

I clean the corrector of my 10" f/20 Maksutov regularly (twice a year) and once every two years take it off completely from the scope to clean the inside as well.   For the more regular cleaning I start  by blowing off any hard residue, dust before using distilled (or good filtered) water with a single drop of cleaning fluid/soap.  Using cotton balls dripping wet from the water, I go over the whole corrector in circular motion and replace cottons often (never reuse).  I tend to do this with the scope pointing down so that any excess water naturally falls on the floor and doesn't make it to the inside of the OTA.  Then dry up with kitchen towel by touching the glass only - no rubbing.  Then use isopropyl alcohol or Baader optics cleaning fluid and go over any areas that have not cleaned thoroughly.   Lastly, I use nail polish (100% acetone) as a final pass all over the glass.  This last one evaporates really quickly and does not leave any streaks.  Contrary to old wives' tales you'll hear, acetone will not remove any coatings that may have been applied to the glass; just keep it away from painted parts.  It is recommended by top opticians such as Roland Christen of Astro-Physics.

Take your time and do it once!

Good luck

Roberto

Edited December 31, 2020 by rrb24

[Nakedgun]

3 hours ago, rrb24 said:

   Lastly, I use nail polish (100% acetone) as a final pass all over the glass. 

Roberto

 

Nail polish remover I think you meant to say, Roberto.

[kirkster501]

Photos taken with a flash make any dust and marks that are present seem much worse than they are.  From the evidence of those pictures I would leave it alone, I have seen very much worse that that.

As and when you do clean it, it is simple - Just as Willie does here.  I did exactly this with my C925.

 

[Kodo65]

Thank you all for your suggestions and help!

[rrb24]

29 minutes ago, Nakedgun said:

 

Nail polish remover I think you meant to say, Roberto.

Indeed!😅

[ngwillym]

Or there's this guy

Telescope Repair - SC Telescopes.com service repair.

 

Did  a great job on reviving my15 year old Celestron C11

[Voyager 3]

12 hours ago, rrb24 said:

Indeed!😅

Phew ! 

[ollypenrice]

While worrying about the blemishes on the corrector plate, take another look at that vast black thing smack in the middle of the light path and totally opaque.  The secondary mirror. Think about it!!

😁lly

[dan_adi]

Don't mind me asking but why buy such a big SCT? In my case (with the 12 inch SCT)  it was aperture fever, and lack of knowledge, and lack of experience .. :)) . I am at the point when the only thing I would use it for is planetary imaging. Perhaps I am just curious why we buy SCTs..?!

On topic. I didn't need to clean my corrector plate, but the youtube videos are very informative. You should give it a try

[Kodo65]

Hi!

Thank you all for your kind suggestions! I decided to let the OTA "pass on"...