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Evolution 9.25 corrector plate bad seal?

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#1 nrcapes

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Posted 14 October 2021 - 02:10 PM

I have had several episodes of liquid water inside my OTA even though it is securely covered. Now there is this white substance coming from the corrector plate. Is this a bad seal? Should it go to Celestron for warranty service?76D26C31-EFFA-402D-A2C2-95E2F80A1250.jpeg



#2 Mike G.

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Posted 14 October 2021 - 02:27 PM

My guess would be that you are getting some significant condensation on the inside and it is wetting whatever Celestron is using for a gasket on the secondary holder.  then, debris from the wet gasket is dripping down with the water and collecting on the inside of the corrector.  if it's a new scope, I would probably return it for cleaning/gasket replacement, then go out and buy a good dew strap and make sure I use it all the time.



#3 Seiten

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Posted 14 October 2021 - 07:55 PM

"securely covered"  

 

Are you saying the moisture is building up while its in covered storage outdoors?  If so, are you using any desiccant near the OTA to try and absorb moisture in the vicinity under the cover?



#4 nrcapes

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Posted 14 October 2021 - 10:49 PM

"securely covered"  

 

Are you saying the moisture is building up while its in covered storage outdoors?  If so, are you using any desiccant near the OTA to try and absorb moisture in the vicinity under the cover?

Yes. Please see duplicate post with same title 



#5 Seiten

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Posted 14 October 2021 - 10:57 PM

Ounces???  WTH?!?  Im assuming you're leaving out there covered with Orion scope cover and during some significant rain.  I have a Telegizmos that I use to cover, but if there is rain in the forecast, Im sure to bring the OTA inside.

 

If you're getting that much water, I gotta think the scope cloak is leaking.  That residue has therefore got to be coming from the cover as well.  

 

Are you absolutely sure that cover is not leaking/seeping?



#6 mlord

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Posted 15 October 2021 - 07:26 AM

If the scope is on soft ground, the cover can act as a moisture collection unit on the inside..



#7 spacemunkee

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Posted 15 October 2021 - 07:50 AM

Thinking of my 9.25 and how the secondary cover rotates to expose the collimation screws, I have to wonder if it is truly sealed or if there is a path for moisture under at the center point to the inside.



#8 nrcapes

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Posted 15 October 2021 - 08:56 AM

If the scope is on soft ground, the cover can act as a moisture collection unit on the inside..

Scope is on a wood deck, but maybe the cover collects moisture anyway.



#9 mclewis1

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Posted 15 October 2021 - 09:44 AM

Meade and Celestron SCTs are not "sealed". There is air flow from various points. Aside from the obvious rear baffle tube opening, and around the corrector for another as the gaskets for the contact between the corrector and tube are often only small and placed in various points around the lip that supports the corrector. 

 

Never rely on the construction of the SCT to keep moisture laden air out ... always work to keep the humidity levels down around your scope in storage. Air movement, keeping the ambient air temps above the dew point, and the use of desiccants are the most popular steps.



#10 nrcapes

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Posted 15 October 2021 - 10:53 AM

Thanks, everyone, for some very helpful thoughts, although it is still a mystery to me how this happens.  I know that the cover is not leaking - I turned it inside out and checked all of the sewn seals. Perhaps the cover just traps humidity, but it's hard to believe that it could trap as much as I have seen. I realize now that Celestron and Meade scopes are not "sealed" but this doesn't explain the accumulation of this white substance on the inside of the OTA near the corrector plate.  For now, I'm going to use a dew heater all of the time the scope is outside and maybe take it inside when rain is forecast.   This does, however, seem overkill so I am going to open a new topic about this.



#11 ddouble518

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Posted 15 October 2021 - 11:29 PM

You need ventilation. Look for boat cover solar powered vents. Your cover is acting like a greenhouse, trapping than condensing the moister onto your scope and corrector plate.

#12 Noah4x4

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Posted 16 October 2021 - 12:01 AM

This won't assist the OP, but CN members in the UK should note that high end manufacturer, Orion Optics UK, based near Stoke on Trent will clean and service any telescope. Prices are listed on the OOUK website.

They stripped down and cleaned my primary SCT mirror (in mild acid), my secondary mirror and corrector plate. They fitted a Starizona Hyperstar gasket which prevents the Fastar fitting coming loose (as mine had), realigned all optics and collimated. They replaced my Phillips collimation screws with easier and safer to use Allen Bolts. They (unprompted) even lined my dust cap with a belt of felt to make it fit more snugly. The process took seven days.

Best £120 I have ever spent on astronomy gear as they corrected some aberations that had evidently existed ever since it left Celestron. It is now so precise that I never have to independent collimate Hyperstar which I leave permanently locked together. Key to this is alignment of primary mirror, corrector plate and Fastar fitting (e.g. Secondary mirror holder). I suspect no amateur/DIY can ever replicate a properly factory aligned and collimated optical train. I highly recommend.

Edited by Noah4x4, 16 October 2021 - 12:05 AM.

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