Eyepiece question

[Sbohana]

I recently bought my first telescope.  A Celestron 130.  To get the hang of things, obviously I pointed the telescope at the moon using a 35mm eyepiece and everything looked fine.  I then switched to the 9mm and I could never get the moon in focus.  Am I doing something wrong or is the moon just to big and bright for a 9mm?

[Putaendo Patrick]

First question: is your low power eyepiece 35mm? Generally they come with 25mm or 20mm in the box.

Second & third questions: what model is this telescope? Astromaster, NexStar etc. And, is it new?

Fourth question: align your telescope on a bright star, does the 9mm eyepiece come to focus? The star should appear as a sharp point of light.

The Celestron 9mm is not the greatest eyepiece, but you shouldn't have any problem using it on the Moon. The Moon's brightness may make viewing it uncomfortable for you, but won't have any impact on focusing. The Moon's size won't effect focus either. Depending on the magnification that the 9mm gives (which in turn depends on the focal length of your scope), you may not see the whole Moon - but the detail you do see should be in sharp focus.

[Mak the Night]

I'm guessing your scope is a 130mm Newtonian with a 650mm focal length. A 9mm eyepiece would give you about a 72x magnification. I was viewing the Moon earlier with a 130mm Newtonian scope with a 4mm eyepiece for 225x. I have a helical fine focuser and the image was a bit hazy even fine focusing. In good conditions I can often get a sharp 300x on the Moon, but at this time of year in the northern hemisphere there is a lot of convected heat in the atmosphere, plus the overall conditions and hazy cloud wasn't contributing to a really sharp image. As the Moon was setting I didn't have time to experiment with magnifications so I stayed with the 4mm eyepiece for the duration. I put it down to atmospheric conditions. It may be that your 9mm eyepiece was giving you too high a magnification on that particular night for the conditions.

 

[iPeace]

I concur with Mak; last night I was sat out with my 15x50 IS binoculars and the Moon kept drifting in and out of focus so I can imagine having problems at higher power.

There will be better nights.

[ronin]

Need to know the scope details. But eyepieces as specified should have been reasonable - maybe the shorter one just happens to be a poor example. THe supplied items are now often very inexpensive designs. So it could just be a case of a poor design that happens to be not very good also. Any markings - letters - on the eyepiece  Like MA, K  besides the focal length?

[Linda]

No what what scope you have, I think you need an additional eyepiece in the range between 9 and 35 mm. I can often not use my shortest eyepiece because of atmospheric issues and often use only the low power and an in-between power. Maybe a 16mm or 20mm would be suitable for you.