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Cleaned My C9.25 Optics Today - Thoughts

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#1 KTAZ

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Posted 09 July 2020 - 07:09 PM

For a 5 month old scope, I was surprised to find dust and dirt inside the tube, on the back of the corrector and on the mirror. The front side was pretty dirty just because I live in the desert. Surprisingly, the primary mirror had a finger smudge and some other sort of residue on an area about 1" square. So I decided to pull the corrector off my C9.25 today and gave it and the primary mirror a bath.

 

I know, I know, I didn't HAVE to clean it. But as a new scope I decided now was the time and then I'll leave it for a few years.

 

I used the mix from ASO http://arksky.org/as...cleaning-system as my baseline but did not include the windex and increased the amount of 99% isopropyl. Probably about a 25% solution. Nor did I filter the distilled water; it's laboratory reagent grade, for crying out loud. I didn't buy it at Safeway.

 

The initial cleaning left some streaks which would not come off using the ASO rinse formula. That just left more streaks. I decided that the PhotoFlo must be the culprit, so I used cotton to lightly swab pure distilled water followed by a very light buffing with the cotton afterwards to remove any remaining haze or discoloration. Very nice.

 

IMHO, PhotoFlo might be good if you have a large optic and are really using a lot of fluid for rinse. But for just a dab and clean, it seems to me to do more harm than good. So now I have a big bottle of PhotoFlo to sell; with only 2 drops used!

 

One other thought. Once I pulled the corrector retaining ring, I was surprised to find that the little nylon allen screws around the perimeter aren't long enough to "retain" it. They seem to be more for protecting the edge of the corrector by ensuring that it never comes into contact with the housing. BE SURE to have your scope tilted sightly skywards because those little screws will not retain the corrector and it could fall forward.


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#2 Beeham

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Posted 09 July 2020 - 08:39 PM

Glad to hear that everything went well for you.  I was a little apprehensive the first time I opened up my SCT, but it's a good experience, because once you've done it, there's no more "magic" - the operation of the device is clearly evident.

 

It's kind of beautiful how such a simple machine works, isn't it?

 

Cheers!



#3 Cpk133

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Posted 12 July 2020 - 08:16 PM

Good grief, try a little research before taking it apart.  I hope you didn't go and snug the centering screws when you put it back together or your corrector might go pop in cold weather or it might show signs of pinched optics.


Edited by Cpk133, 12 July 2020 - 08:18 PM.


#4 KTAZ

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Posted 12 July 2020 - 09:28 PM

Good grief, try a little research before taking it apart.  I hope you didn't go and snug the centering screws when you put it back together or your corrector might go pop in cold weather or it might show signs of pinched optics.

I’m not sure what you are talking about. Are you?


Edited by KTAZ, 12 July 2020 - 09:29 PM.


#5 smccully

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Posted 12 July 2020 - 11:17 PM

Be careful tightening the retaining ring, the first time I took it off my EdgeHD 11 I wasn't paying attention and tightened the screws a little too hard and the correct plate cracked like a lightning bolt going through it. 

 

 

Had to be returned to Celestron for a new one. 



#6 mrki233

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Posted 14 July 2020 - 04:51 PM

I recently cleaned my 6SE corrector, front and back.  There was some haze on the inside of the corrector.  Removing the ring and corrector for the first time was a little nerve wracking, but it all turned out okay.  As others have said, be careful tightening the retainer ring screws.  I made a note of how tight they were before taking them out and put them back in to what felt like the same tension.  I also made an index mark on the corrector and the end collar to put the glass back in the same orientation.  I've had the 6SE for over nine years and have cleaned it once.  Next time will be more familiar and less scary.

 

Good advice to have the scope tilted slightly up, keeping the corrector in place.  Gravity is a, well, you know...

 

Now if I can only summon the courage to open up my CPC 1100.  That seems like a different beast altogether!

 

"dab dab dab, blot blot blot" repeat.


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#7 KTAZ

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Posted 14 July 2020 - 05:24 PM

I recently cleaned my 6SE corrector, front and back.  There was some haze on the inside of the corrector.  Removing the ring and corrector for the first time was a little nerve wracking, but it all turned out okay.  As others have said, be careful tightening the retainer ring screws.  I made a note of how tight they were before taking them out and put them back in to what felt like the same tension.  I also made an index mark on the corrector and the end collar to put the glass back in the same orientation.  I've had the 6SE for over nine years and have cleaned it once.  Next time will be more familiar and less scary.

 

Good advice to have the scope tilted slightly up, keeping the corrector in place.  Gravity is a, well, you know...

 

Now if I can only summon the courage to open up my CPC 1100.  That seems like a different beast altogether!

 

"dab dab dab, blot blot blot" repeat.

I guess that was the strange thing...there literally was zero contact between the nylon heads and the edge of the corrector. Now, I am cetain that they are just there for spacing and protection, not really for retention, but having 1/16" of play between pretty much all of them was a surprise. Heck, if i'm transporting it and hit a nasty bump in the road, that plate could even shift a bit.

 

And you make a point that I forgot about. My corrector was also NOT indexed. I used painters tape and cut it with a razor before removing the corrector, and I also used a permanent black marker to further index the edge of the corrector and the housing. In the old days you could depend on there being an index mark put there by the bench tech. No more.



#8 John Miele

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Posted 14 July 2020 - 05:25 PM

Why does everyone think he is going to destroy his corrector? I don't think he ever said he was planning to substitute longer screws. And besides did he not say this

 

"   little nylon allen screws around the perimeter aren't long enough to "retain" it....

 

So it is impossible for him to even put any pressure at all on the corrector....ya'll chill out a bit...


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#9 KTAZ

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Posted 14 July 2020 - 05:47 PM

Why does everyone think he is going to destroy his corrector? I don't think he ever said he was planning to substitute longer screws. And besides did he not say this

 

"   little nylon allen screws around the perimeter aren't long enough to "retain" it....

 

So it is impossible for him to even put any pressure at all on the corrector....ya'll chill out a bit...

It's actually a little humorous at times...some folks seem to think that a fly running into their corrector plate is poing to leave sleeks and wing prints in the coatings. lol.gif

 

Be careful tightening the retaining ring, the first time I took it off my EdgeHD 11 I wasn't paying attention and tightened the screws a little too hard and the correct plate cracked like a lightning bolt going through it. 

 

 

Had to be returned to Celestron for a new one. 

That is a major bitc....

 

Was that ring steel? Mine is plastic, has a thin rubber gasket adhered to it and goes against a fiber washer before it touches the plate. Plus, the tappings for those little screws are not very deep, so I would think I'd strip them before I crack a corrector. I try not to put too much torque on those as it is.



#10 Cpk133

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Posted 17 July 2020 - 08:51 AM

It's actually a little humorous at times...some folks seem to think that a fly running into their corrector plate is poing to leave sleeks and wing prints in the coatings. lol.gif

 

That is a major bitc....

 

Was that ring steel? Mine is plastic, has a thin rubber gasket adhered to it and goes against a fiber washer before it touches the plate. Plus, the tappings for those little screws are not very deep, so I would think I'd strip them before I crack a corrector. I try not to put too much torque on those as it is.

What's funny is you were surprised the centering screws weren't making contact and warning people not to remove the retaining ring with the scope pointed down.



#11 KTAZ

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Posted 17 July 2020 - 09:40 AM

What's funny is you were surprised the centering screws weren't making contact and warning people not to remove the retaining ring with the scope pointed down.

What’s funny is your inability to read or provide anything of value to the folks in this discussion. This is twice now you’ve made inaccurate and out of context statements regarding what I did or said.

 

Why don’t you troll another thread?



#12 Cpk133

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Posted 17 July 2020 - 10:47 AM

 

One other thought. Once I pulled the corrector retaining ring, I was surprised to find that the little nylon allen screws around the perimeter aren't long enough to "retain" it. They seem to be more for protecting the edge of the corrector by ensuring that it never comes into contact with the housing. BE SURE to have your scope tilted sightly skywards because those little screws will not retain the corrector and it could fall forward.

I'm sorry for "trolling" you and taking things out of context.  Perhaps it would have been better had I I just said that the centering screws need to have a gap to the lens to allow for thermal expansion.  If the screws were making contact at room temperature, under a clear winter sky, they would be pinching the optics.  The centering screws may have been metal when this vid was shot (not mine)

 

https://m.youtube.co...h?v=amXDRYs25xs

 

The screws around the retaining ring and resultant compression are enough to keep the corrector from sliding to and fro. 



#13 Andrew Brown

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Posted 17 July 2020 - 11:34 AM

Good grief, try a little research before taking it apart.  I hope you didn't go and snug the centering screws when you put it back together or your corrector might go pop in cold weather or it might show signs of pinched optics.

Or nothing of the sort might happen.

 

Interesting thing those centring screws, what if they have been factory set to give an offset for a less then central secondary hole or secondary holder that is not in line with optical axis or, or, or, or......

 

One thing for sure.

 

I felt blessed not having the farstar gubbins to add into the [miss] alignment mix post rebuild..especially since even if I did have it I have no intention of ever using it ...


Edited by Andrew Brown, 17 July 2020 - 11:38 AM.

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#14 Cpk133

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Posted 17 July 2020 - 01:32 PM

Or nothing of the sort might happen.

 

Interesting thing those centring screws, what if they have been factory set to give an offset for a less then central secondary hole or secondary holder that is not in line with optical axis or, or, or, or......

 

One thing for sure.

 

I felt blessed not having the farstar gubbins to add into the [miss] alignment mix post rebuild..especially since even if I did have it I have no intention of ever using it ...

Exactly what they're for, especially the edge scopes where optical centering is more demanding.



#15 KTAZ

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Posted 29 July 2020 - 02:02 PM

Or nothing of the sort might happen.

 

Interesting thing those centring screws, what if they have been factory set to give an offset for a less then central secondary hole or secondary holder that is not in line with optical axis or, or, or, or......

 

One thing for sure.

 

I felt blessed not having the farstar gubbins to add into the [miss] alignment mix post rebuild..especially since even if I did have it I have no intention of ever using it ...

I did finally get a response from Celestron; they did confirm that they are to be used for centering the corrector.

 

However, that did not solve my issue of not being able to adjust them since all but 1 of mine were NOT touching the corrector at all. Tightening or loosening did not move the nylon tip. After a bit more fiddling I found this:

mdC8EM7.jpg

I did not know that there were actually 2 screws in there; one for the tip itself and the other to "lock" the tip in place. Nor did Celestron tech support mention this. Mystery solved. All I had to do was center the plate with them, leave them just barely in contact with it, and then lock down the other screws.




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