focusing my telescope

[johnp51]

Hi, I have just bought a Celestron C9.25 XLT ota, I was using it last night, and I noticed that I could not focus to a sharp image, on the moon or a star, does this mean my culmination is out, or some thing else ????

[ronin]

Not sure about Barnstable but the sky was never quite clear here over the last few nights, and that means you never quite achieve a good focus. You can see the stars by eye but the scope is more critical.

You may also have had dew/moisture on the front corrector, although that tends to be more apparent.

[hobsey]

How long did you allow it to cool down for as these scopes need quite a long cooling down period.

It could have been the thermals in side the scope.

[Owmuchonomy]

Hi, I have just bought a Celestron C9.25 XLT ota, I was using it last night, and I noticed that I could not focus to a sharp image, on the moon or a star, does this mean my culmination is out, or some thing else ????

I have this scope.  I think you are asking if it needs collimating.  I would be very surprised if that is the case.  Mine is 7 years old and these scopes generally hold collimation.  How much could you actually see?  Can you let us know what is in your viewing train.  For example are you using a diagonal and what eyepieces have you tried?  As Anthony says you need to leave these scopes for 60 to 90 minutes outside to cool off.  Leave the main objective cap on whilst you do this but remove the smaller cap from the visual back.

[Cornelius Varley]

Hi, I have just bought a Celestron C9.25 XLT ota, I was using it last night, and I noticed that I could not focus to a sharp image, on the moon or a star, does this mean my culmination is out, or some thing else ????

Have you released the mirror locking screws ?  http://www.celestron.com/support/manuals-software page 31

[rwilkey]

Hi there, you will need a dew shield for the front of the scope as this is the first bit that mists up, found here: http://www.firstlightoptics.com/dew-prevention/astrozap-flexible-dew-shield.html

[Moonshane]

what magnification were you using? more often that not, this is limited to 200x approx in the UK for planets although I do regularly use more. this assumes a fully cool and well collimated scope. even then, the image is not 'solid' at 200x (sometimes even lower) as the seeing means it waxes and wanes around a central 'best focus point'. This best focus point is where you want to leave the focuser and wait for moments of good seeing.

200x in your scope would (I think) equate to a 12mm eyepiece. if you were using a lot more, this will be the problem I reckon.