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C9.25 focus problems

markyt1

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markyt1

markyt1

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This is the rear of the scope so just the standard focuser.  I'll check the screws as I did have a another shoe for a finder scope on it and removed it the other week but I'm sure it was working of after that.  

DSC_0413.JPG

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Phil Fargaze

Phil Fargaze

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I see some expensive ornaments on Antiques Roadshow but a C9.25 is too good to not be used as a scope! Have you considered the secondary, (or has it already been mentioned) I see that the scope has the fastar conversion device. I`m not familiar with it myself but maybe this has been disturbed, turned or twisted somehow.

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markyt1

markyt1

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Well had some time to try out several of the suggestions mentioned.  Still no luck.  I've taken the focuser on and off, checked for screws that may be impeding the mirror.  The scope moves up and down the baffle when I turn the focuser with no obvious problems.  The baffle is secure and dosent move when I install the visual back.  The secondary appears fine. There is no observable damage to the OTA either,  I've used different eyepieces and diagonals.  Im truly gutted.  This has stumped me and I think I'll be making enquiry with my insurance as there seems to be something catastrophically wrong with the scope. Thanks for all the info people it's appreciated.  ?

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nddeyne

nddeyne

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On 29 May 2016 at 18:35, markyt1 said:

I've attached a pic of the scope showing the view down the ota.

At what distance did you take this picture (posted Sunday at 18:35)? Did you take it with a mobile phone?

Just asking, 'cause I can't seem to be able to reproduce the same when I try it with my iPhone on my scope, unless I'm 60 cm away... And at this distance I only see the OTA, not the complete setup including the tripod. Your picture looks like it's been taken at a far greater distance. At 1m and more, the reflection of the secondary mirror assembly is almost completely filling the surface of the primary mirror, regardless of the position of the focuser. Your picture only shows a fraction of that.

It's indeed a very strange issue, more so as it just seemed to appear after the scope being "at rest" for some time. It goes in against all root cause problem solving techniques... (I'm in technical maintenance). Are you absolutely sure that it didn't got kicked, bumped or tampered with unbeknown to you? Someone fiddling with it while you were out? Certainly the issue you mentioned about the image "jumping" to the side of the viewing field has me puzzled! Something should be loose for that to occur in my honest opinion...

Oh man... I surely hope you can pinpoint the problem somehow, it's a far to nice scope to serve as an ornament!!!

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Willie

Willie

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Hi , just a thought, it has been mentioned before, check out your screws, etc.. I had a C11, and had the same probleme..One of the screws was in too far, therefore gently touching the Mirror..

 

Going back to what you mentioned before, "as I did have a another shoe for a finder scope on it and removed it the other week".. your scope was fine before, since you have made a slight change... whay may be happening, is that the mirror is yes moving, but rubbing against a srew, as we say (its squinty:icon_biggrin:)  common Jimmy , I would completly remove the new  shoe, & screws, and try again..

We want to see your scope working..

 

Cu John..

 

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markyt1

markyt1

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Between work not had much chance to fiddle about more withheld scope. Attached are a couple of pictures with the mirror at each end of the focus range.  If anyone can see any problems??  There are definitely no screws impeding the mirror as I have checked this fully now

  

  

DSC_0415.JPG

DSC_0416.JPG

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SkyGibbon

SkyGibbon

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I am not sure you can come to focus without a diagonal, unless you add an extension to the visual back. I could be wrong on that though. Which way are you turning the focuser when you feel it is coming closer to focus? The sudden moving to the outer edge sounds like major mirror flop.

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michael8554

michael8554

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Just general googling of your problem with a Celestron SCT (not necessarily the 9.25) suggests that your primary baffle, that the primary slides on, may be loose:

"some noted that the lock down collar for the primary was loose, causing gross tilting on the baffle".

Though how this would suddenly happen between viewings isn't clear....

Can you describe again what happened way back when you first noticed the problem?

Were you using exactly the same arrangement of micro focuser, diagonal, and eyepiece?

Only this time focus was totally out, although you hadn't altered the coarse focus between times?

Michael

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markyt1

markyt1

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Haven't updated this as I haven't had any time to get outside with the scope plus this summer weather is slightly hindering any opportunities.  I took off all the screws along the bottom cell the other week and reinstalled them.  The scope then sat in the kitchen for a while before I got a chance to take it out.  Pinpoint focusing!  Now I've had scopes for a few years and there was no user error in my problem.  I honestly don't know what the heck was going on but it's back to a fully functioning scope.  Thanks to all that posted advice.  Go figure??? 

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  • 2 months later...
usingen1

usingen1

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On 8.6.2016 at 22:36, michael8554 said:

Just general googling of your problem with a Celestron SCT (not necessarily the 9.25) suggests that your primary baffle, that the primary slides on, may be loose:

"some noted that the lock down collar for the primary was loose, causing gross tilting on the baffle".

Though how this would suddenly happen between viewings isn't clear....

Can you describe again what happened way back when you first noticed the problem?

Were you using exactly the same arrangement of micro focuser, diagonal, and eyepiece?

Only this time focus was totally out, although you hadn't altered the coarse focus between times?

Michael

I just got a brand new 925 visually with 2 in celestron diag. and FR 6.3 and baader mk III was great, AP was out of focus big time got some advice and will try this next, in AP mode use a t adapter at first i will try the 50 mm from cel. will fill you in on the outcome...Ernest

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