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Scratche on a used celestron edge hd 11'' corrector plate...

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#1 aeroseb

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Posted 12 October 2019 - 12:51 PM

 Hello, 

I've just bought a used CPC deluxe edge hd 1100. I haven't seen it with the seller the day of the purchase but there's a scratche inside de the corrector plate. I know that I better should to leave this in place but it's some kind disturbing me.  What's your opinion ? It looks like a sharpie pencil but i'm afraid it could be worst...  

Thanks very much!

20191011_023537.jpg


Edited by aeroseb, 12 October 2019 - 12:56 PM.


#2 Jon Isaacs

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Posted 12 October 2019 - 12:55 PM

Hello, 

I've just bought a used CPC deluxe edge hd 1100. I haven't seen it with the seller the day of the purchase but there's a scratche inside de the corrector plate. I know that I better should to leave this in place but it's some kind disturbing me.  What's your opinion ? It looks like a sharpie pencil but i'm afraid it could be worst...  

Thanks very much!

Can you provide a photo?

 

Jon



#3 aeroseb

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Posted 12 October 2019 - 12:58 PM

yes, another one more here :
20191011_022501.jpg
 



#4 pyrasanth

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Posted 12 October 2019 - 12:58 PM

I doubt a scratch of that size is going to make any difference. However it is somewhat of a mystery how the corrector got scratched on the inside- are you sure the corrector is genuine- have you star tested the telescope?

 

Note- there does appear to be a coating being shown so perhaps it is a genuine plate.


Edited by pyrasanth, 12 October 2019 - 01:01 PM.


#5 aeroseb

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Posted 12 October 2019 - 01:03 PM

as it's from the inside of the CP my guess is it was made during the factory process but i'm curious about the nature of this scratch and how to possibly getting off it!  smile.gif thks!


Edited by aeroseb, 12 October 2019 - 01:03 PM.


#6 Stevegeo

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Posted 12 October 2019 - 01:25 PM

I highly doubt first that it was a factory scratch...though I suppose it could happen..

Second a scratch that small would not affect the view that much unless it's Deep and wide .

 

I have seen correctors that were cracked nearly across yet not noticable when looking through the eyepiece..unless comparing to a new scope ..

 

Had a C8 with a chip in corrector on the edge, thumbnail size, hardly noticable view..bought a new corrector from eBay from a dropped C8 ( busted primary)...cheap.. did a swap...and the result a near perfect C8 I still have .



#7 pyrasanth

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Posted 12 October 2019 - 01:27 PM

If it is determined that it impacts no problems to the images the telescope produces then it is not worth the cost of repair. I remember a story where one of the primary mirrors of an observatory telescope was damaged by gunshots- the mirror was damaged https://www.nytimes....irror-by-7.html The image quality was unaffected.


Edited by pyrasanth, 12 October 2019 - 01:33 PM.


#8 Mitrovarr

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Posted 12 October 2019 - 01:28 PM

You can't fix a real scratch. However, sometimes streaks of grease or other contaminants can look exactly like scratches. I came into an old-style rubber armored C90 about 15 years ago that had a screw bouncing around inside the scope. I got it out, but despaired of ever fixing the scope because it looked exactly like it had been scratched like crazy by the screw. But, eventually, just messing around, I tried cleaning it. All the 'scratches' came right off (also the baffle tube tongue2.gif). They were just grease from the focusing mechanism, transferred onto the inside of the lens and the primary mirror by the screw.


Edited by Mitrovarr, 12 October 2019 - 01:29 PM.

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#9 Erik Bakker

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Posted 12 October 2019 - 01:34 PM

I can see why this discomforts you. I would carefully take the corrector out, make sure to have alignment marks so you can put the corrector back in the proper way. Clean inside and outside with pure alcohol and see how it looks after that. After putting the corrector back in, make sure that you start using the scope in the way you intended to when you purchased it: observing the heavens. Just take it from there ....



#10 aeroseb

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Posted 12 October 2019 - 01:45 PM

wow so much answers in a short time, I really appreciate your help guys!  Mitrovarr, interesting story... Indeed, regarding the scratch on my CP, it looks like it has been made with somekind of rubber material...   

Btw, the seller knew this issue... The day of the purchase (3 days ago) I found in the stock packaging a letter from him to the merchand explaining a ''scratch'' issue... It suddenly took off of my hands the letter and said it wasn't my affair... he just swore to me that  the edge OTA has never been opened... 


Edited by aeroseb, 13 October 2019 - 12:19 AM.


#11 Mitrovarr

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Posted 12 October 2019 - 01:49 PM

If it helps, the scratch (or mark if it isn't really a scratch) almost certainly makes next to no difference in the images.



#12 aeroseb

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Posted 13 October 2019 - 12:15 AM

Is there something specific to the edge hd 11'' OTA to know regarding the best way to take off the CP, a part that put it back in his right way ? (I mean, is there a silicone or special shim (cork) in this model)

I don't want to make things worse than it be...



#13 Joe1950

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Posted 13 October 2019 - 12:48 AM

I know nothing of the Edge 11”, but on some SCTs and MCTs, you can take the entire corrector housing off and get at the back surface that way.  It avoids taking the glass out of its cell and risking more damage like a clam chip or returning it in the wrong orientation or tilted.

 

Myself, if you have to remove the naked glass, I’d pass on that. There are too many things that can go wrong with a large thin piece of glass to be concerned. I don’t think there would be any advantage at all by getting the mark removed.



#14 cturek

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Posted 13 October 2019 - 07:08 AM

I wouldn't do anything with that scratch. This is a pic of an EdgeHD8 that I purchased for parts from a CN member. When he had it shipped to him, the secondary mirror came of it's base plate and was sliding all over the inside of the OTA during shipment. These are scratches. They go all the way around the primary. The corrector plate had numerous scrapes along with a lot of the reflective coating on the secondary getting rubbed off. You can see the reflection of the secondary (along with a red dot that I center marked for playing with the TAK collimating scope.

 

Just for grins, I set this up and viewed Jupiter. Believe it or not, the image wasn't that bad. Got a sharp focus with multiple bands visible.

 

I'm only posting this to agree with some of the other posters that your scratch isn't going to make any difference in the quality of view. I'd leave it alone for sure. 

 

 

 

Carl 

Attached Thumbnails

  • EdgeHD 8 Scratches.jpg

Edited by cturek, 13 October 2019 - 07:10 AM.

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#15 Migwan

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Posted 13 October 2019 - 09:10 AM

Doesn't look like a scratch to me.  Even if it is, it will not likely effect the apparent view thru the scope.   Personally, I don't think its all that big a deal to clean the optics of an SCT and somehow, they can eventually get gunky.      Here's a video

 

jd



#16 aeroseb

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Posted 13 October 2019 - 10:38 AM

ok! thks everyone for your recommandations....I'll leave it in place and won't try to remove or clean the CP...for now, at least :)
Clear Skies.


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#17 Joe Eiers

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Posted 13 October 2019 - 02:00 PM

  I used to think that a scratch like that was a catastrophic event to my corrector plate and would ruin otherwise excellent views.  After doing this my whole life I can tell you definitively there are very, very, very few people that could, if ever, be able to spot the difference on a planet.  For DSO's it's just not going to to do a thing.

   Enjoy!

     Joe


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#18 Joe1950

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Posted 13 October 2019 - 03:20 PM

I’ve taken optics apart to clean them and with dust getting on them and a blue like film from the cleaning agent, etc, they ended up worse!

 

I once bought a very early model ETX-90. Really good optics and clean as a whistle. Except for one small smudge on the primary mirror. 

 

That small smudge just bothered the heck out of me until I decided to clean it off. I used the prescribed solution of alcohol and distilled water and gently wiped the smudge.

 

Well, I got the smudge off okay... all the way down to the bare glass. The cleaning took the aluminum off too. It was about 1/8” x 3/8” bare glass. I never noticed any difference in the views. None at all. It’s still there. 

 

My my motto has become: When in doubt, don’t!


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#19 aeroseb

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Posted 13 October 2019 - 03:49 PM

usefull advises, wisdom has spoken smile.gif

Cheers


Edited by aeroseb, 13 October 2019 - 08:06 PM.

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#20 BravoFoxtrot

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Posted 13 October 2019 - 03:57 PM

I wouldn't do anything with that scratch. This is a pic of an EdgeHD8 that I purchased for parts from a CN member. When he had it shipped to him, the secondary mirror came of it's base plate and was sliding all over the inside of the OTA during shipment. These are scratches. They go all the way around the primary. The corrector plate had numerous scrapes along with a lot of the reflective coating on the secondary getting rubbed off. You can see the reflection of the secondary (along with a red dot that I center marked for playing with the TAK collimating scope.

 

Just for grins, I set this up and viewed Jupiter. Believe it or not, the image wasn't that bad. Got a sharp focus with multiple bands visible.

 

I'm only posting this to agree with some of the other posters that your scratch isn't going to make any difference in the quality of view. I'd leave it alone for sure. 

 

 

 

Carl 

Holy cow!  That is hard to look at, Carl!  

 

I agree with Carl and other posters.  I suspect there is no discernible difference in performance. Cosmetic flaws have a psychological way of making us believe performance is degraded. We then feel compelled to take corrective action.  This is usually a bad idea.  

 

I will say this after being in the optical field for 20 years, I see a ton of problems introduced with improper cleaning.  Field, lab...doesn’t matter...I’ve seen many optics degraded or even destroyed with improper cleaning techniques.  Stay away unless performance is unacceptably degraded.


Edited by BravoFoxtrot, 13 October 2019 - 03:58 PM.

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#21 aeroseb

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Posted 13 October 2019 - 05:09 PM

I was also afraid for the reselling value... 



#22 BravoFoxtrot

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Posted 13 October 2019 - 05:17 PM

I was also afraid for the reselling value... 

Good point and the crux of the matter, IMO.



#23 Tyson M

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Posted 13 October 2019 - 06:56 PM

My guess is that a scratch like that, if on the outside is likely from someone slipping with an Allen key to collimate it in the dark.

Shouldn't affect the views but definitely hurts resale value and I would not be happy looking at it all the time.

#24 aeroseb

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Posted 13 October 2019 - 08:15 PM

My guess is that a scratch like that, if on the outside is likely from someone slipping with an Allen key to collimate it in the dark.

Shouldn't affect the views but definitely hurts resale value and I would not be happy looking at it all the time.

Yes, but the fact is this scratch's inside the CP! 
However I can't believe that Celestron QC didn't see it and let this OTA leave the factory with a CP in this state... It would have been very surprising, don't you think ?


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#25 Joe1950

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Posted 13 October 2019 - 10:14 PM

It would be very surprising, but not impossible.

 

I can’t speak for others, but if I were buying the scope from you I’d be much, much more concerned with how it performed optically than with that mark.

 

If you said it shows a very good star test or some other description of optical quality, I’d rather have it with the mark than a scope with soft optics and a perfectly clean corrector.

 

If you have used the scope and feel it’s a real performer, especially on planets, that would be another reason not to disassemble it. To me, anyway. 

 

Again I no nothing of how the scope is put together, but taking it apart and getting it back exactly as it was might be difficult. Would you be sure the corrector is centered exactly as it originally was? Would you tighten the retaining mechanism the same? Could it go back slightly tilted to as it was before? These would be things I’d be more concerned with, but that’s just me.

 

And believe me, I know how such a thing can stick in your mind and never get out.

 

But from experience working on scopes and ham radios as well, there are too many variables and pitfalls that can and do happen when you ‘open it up.’

 

Again, just my approach, having been there.

 

 

- I assume when the scope is moved on its mount, you don’t hear anything rolling around?

- If you take the visual back hardware off the scope, can you see the mark from the back of the scope through the primary baffle - next to the secondary? 




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