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Cat owners - don’t do this!

cassegrain Celestron SCT
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#1 Rgwood88

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Posted 31 May 2020 - 06:29 PM

Well after a two year absence from observing  I pulled out my Celestron CPC 800 this weekend. I was preparing to place it back in its case and as I have always done in the past, I was turning the focuser to bring the mirror all the way back. The tube was pointing down.....and the mirror came loose and broke the corrector. I remember reading about this, probably here on Cloudy Nights. I am not real sure what happened mechanically to cause this but as a rule, don’t adjust the focuser if the scope is pointing down! 

Any body have any idea what Celestron charges to replace the corrector, and if the results were acceptable?


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#2 RichA

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Posted 31 May 2020 - 07:11 PM

That's terrible.  I had no idea they had no retainer for the primary mirror.  I think they need to replace the whole optics set, at least that's what they said before, the mirrors were ground to match the corrector.  I broke a corrector decades ago and that's what they did.  Then it cost $450 for a C8 repair.  Probably more now.



#3 skybsd

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Posted 31 May 2020 - 07:23 PM

Hello. 

 

Well after a two year absence from observing  I pulled out my Celestron CPC 800 this weekend. I was preparing to place it back in its case and as I have always done in the past, I was turning the focuser to bring the mirror all the way back. The tube was pointing down.....and the mirror came loose and broke the corrector. I remember reading about this, probably here on Cloudy Nights. I am not real sure what happened mechanically to cause this but as a rule, don’t adjust the focuser if the scope is pointing down! 

Any body have any idea what Celestron charges to replace the corrector, and if the results were acceptable?

Too bad about your scope there., 

 

I'd suggest your contacting Celestron directly to get facts and up to date information and guidance on options currently available for your situation., 

 

Best.., and good luck! 

 

skybsd 



#4 jwheel

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Posted 01 June 2020 - 07:22 AM

bawling.gif


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#5 EXT64

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Posted 01 June 2020 - 07:31 AM

Wow, that is horrible.  There are retainers for the primary, so very strange.  Did just the mirror come loose, or the entire mirror and mirror holder?

 

C8 scopes are fairly cheap - so a full optics swap or OTA swap may be the most cost effective approach.



#6 elwaine

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Posted 01 June 2020 - 09:00 AM

So sorry that happened. 
 

Why were you attempting to retract the primary mirror prior to putting the scope away? That’s something I never did and don’t remember reading about. Did I miss something? Is that a recommended act prior to storage?



#7 Jon Isaacs

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Posted 01 June 2020 - 09:17 AM

I'm very sorry to hear of this mishap. :(

 

I'm wondering if a retainer was missing or if this is just how it is??

 

Jon



#8 RalphMeisterTigerMan

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Posted 01 June 2020 - 09:30 AM

Yes, I agree. 

 

I will have to add several to the DO NOT do to your Cat:

 

- Pick your Cat up by the tail! They really hate that so never, ever do that!

- Compare your Cat to your Dog while they are both there in front of you! 

- Dress your Cat in cute outfits. I know lots of people do this and post videos on youtube but think about your cat's self-esteem. His cat friends may watch those videos and your cat will be humiliated.

- Make him/her walk a treadmill, unless they really need to lose weight.

- Force him/her to watch YOUR favourite TV shows or movies. Perhaps give your cat the option to choose something on TV/Netflix or what-ever you have.

- Threaten to replace him/her with a NEW cat with all the new upgrades and options...

- Hide a Rubber Chicken in the liter box.

- Try to get your cat to sit on a Woo-pee cushion.

- Shake his/her paw with a joy-buzzer.

- Take your Cat to a fish-market.

 

Do take very good care of your Cat and treat him/her with love and respect!

 

Now, as to the optical kinds of cats. When you are doing public outreach Astronomy, make sure to the spectators NOT to touch any of the equipment. One time a lady decided to touch the corrector plate of my old Meade 2120 LX5. I said seriously lady, you should never touch optical glass of any kind. 

 

Do NOT leave your Cat unattended during public events, especially when observing the Sun with a white light solar filter. Believe it or not, a member of the public, while viewing thru my friends scope, demanded that he "remove" the solar filter so that he could get a "real-life" view not hindered by a Solar Filter!

 

So, let's hear it for Cats, both the furry-quadrapeds and the optical kind! Yeah Cats!

 

LOL! Clear skies!

RalphMeisterTigerMan


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#9 Paul Skee

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Posted 01 June 2020 - 11:29 AM

Someone asked about reason for retracting the primary for storage, here is a link to a document that has a little info:https://www.celestro...91f609348&_ss=r  The last 2 bullet points are relevant. I personally retract the mirror every time prior to putting it away. I also occasionally cycle the mirror to the extreme ends of travel. It keeps the grease spread on the baffle. My C-11 had horrible mirror shift when it was new. I was advised to run the focuser all the way in and out a few times. This action virtually eliminated the shift. I've never heard of a mirror dropping out like that, perhaps there was a pre-existing issue with the mechanism. I pretty much keep mine horizontal when stored.


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#10 WadeH237

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Posted 01 June 2020 - 01:51 PM

Ouch!  Sorry that happened.

 

For what it's worth, that should not happen.  There is a retainer that keeps the mirror from falling forward like yours did, so it sounds like there was a problem with the retainer.  Also, on the smaller SCTs, I don't bother to set the mirror to a specific position for storage.

 

With my C14, there are shipping lock screws that require the mirror to be all the way back to engage.  So for my C14, my routine is to pull the mirror all the way back and tighten the shipping screws.  When I set it up the next time, I release the screws, turn the focuser to move the mirror all the way forward and then half way back.  That distributes the grease on the focus shaft and gets me to a starting place for focus.

 

With a C8, I don't think that the mirror is heavy enough to be a concern for storage and shipping.  It is a good idea to run the mirror fully back and fully forward periodically, though, to ensure that the grease is distributed.  The focuser is essentially a long, threaded shaft that pushes or pulls on the mirror when you turn it.  It you keep it near focus all the time, it can get a bit sticky, hence the suggestion to rack it all the way back and forth once in a while.

 

As for replacement, the last I heard, Celestron does not replace individual correctors, primary mirrors or secondary mirrors.  They replace the whole set of optics.  But do be sure to contact them, as my information is many years old, and things might have changed.



#11 Ettu

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Posted 01 June 2020 - 06:34 PM

Ouch! is right...!

I DID have a laugh though, (sorry)

When my wife, looking over my shoulder, read the title to your thread, and said, I bet that's going to be about cat hair getting into their scope!  I wondered, hmmm, she might be right!?

 

As it happens, I had just opened and cleaned my C11 Edge mirror and blew out all the dust, so you see where my head was at,

With the Edge there's a snap ring on the end of the baffle tube to prevent this kind of thing from happening. Is there by chance provision for such on your scope?, and it just wasn't there?

And would you believe, after reassembling my scope, guess what I noticed lying on the bench, having forgotten to put it back on the baffle tube?

 

As others have mentioned, the optics are sold or replaced as matched sets. I don't know, but doubt if they'd sell them to you, to replace yourself, probably a policy for replacing them only in house. But I don't know. The good (?) news is that you'd effectively get a new scope with pristine optics.



#12 RichA

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Posted 01 June 2020 - 11:30 PM

Someone asked about reason for retracting the primary for storage, here is a link to a document that has a little info:https://www.celestro...91f609348&_ss=r  The last 2 bullet points are relevant. I personally retract the mirror every time prior to putting it away. I also occasionally cycle the mirror to the extreme ends of travel. It keeps the grease spread on the baffle. My C-11 had horrible mirror shift when it was new. I was advised to run the focuser all the way in and out a few times. This action virtually eliminated the shift. I've never heard of a mirror dropping out like that, perhaps there was a pre-existing issue with the mechanism. I pretty much keep mine horizontal when stored.

If mirror shift is say 1 Jupiter diameter, you are doing well.  This is downright weird.  There has to be some kind of c-clip or other retainer on the focus rod at least.


Edited by RichA, 01 June 2020 - 11:30 PM.


#13 EXT64

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Posted 02 June 2020 - 07:26 AM

My older C9.25 had a screw in the focuser threaded rod to stop it but no C-clip on the baffle tube.  I bought it used though, so it is possible someone else lost it.



#14 TG

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Posted 02 June 2020 - 09:57 PM

The one SCT I disassembled completely, a C9.25, had a rubber O ring in a groove to prevent the mirror assembly from falling off. I wonder if the OPs scope was missing such an O ring. Might get a lower repair price from Celestron if that’s the case.

#15 Astrojedi

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Posted 03 June 2020 - 09:39 AM

Rgwood, sorry to hear about your scope. I have owned multiple SCTs (15 over the past 20yrs and never had an issue. I feel this might be a defect with the scope.

 

Someone asked about reason for retracting the primary for storage, here is a link to a document that has a little info:https://www.celestro...91f609348&_ss=r  The last 2 bullet points are relevant. I personally retract the mirror every time prior to putting it away. I also occasionally cycle the mirror to the extreme ends of travel. It keeps the grease spread on the baffle. My C-11 had horrible mirror shift when it was new. I was advised to run the focuser all the way in and out a few times. This action virtually eliminated the shift. I've never heard of a mirror dropping out like that, perhaps there was a pre-existing issue with the mechanism. I pretty much keep mine horizontal when stored.

This guidance from Celestron is interesting. I was not aware of it and have never followed it (maybe I should?). These days my large SCTs are permanently mounted on a pier in my observatory. Storing vertically is not really an option.

 

These seem like long term storage instructions to me. Also note that moving the focuser and pointing the scope downward (or upward?) probably should not be done at the same time. In my experience the focuser is typically most stable in non vertical orientations. 
 

Hope you get this resolved with Celestron.


Edited by Astrojedi, 03 June 2020 - 09:41 AM.


#16 charlesgeiger

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Posted 07 June 2020 - 12:50 AM

Not funny at all.  Sorry this happened.  As others have said, there should be a C-clip on the baffle tube that you could see from the front of the telescope.  There should be a grove in the baffle tube (I am speaking of the integral baffle tube which is a direct connection to the rear cell).  Your mirror assembly with its baffle tube rides over the central tube.  And, again, it is prevented from coming off because of the focuser and the C-clip.  If the focuser rod should somehow come loose and the mirror slip forward due to the tube being pointed down, the C-clip would stop it from crashing down.  Make sure there is a C-clip in the remains.  If there is not, then Celestron should be liable for the damage.  If you purchased this new from any dealer, this should be investigated.  

Now I am speaking of the Celestron's that were made prior to 2005.  I will check my C11 Nexstar and see for sure.  My old C14 has the C-clip.  I hope you have it insured and can have the optics replaced.  Please let us know how things turn out.

Charlie




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