Question about Telescopes

2 Answers

Fuzzy bright stars with my Celestron CPC 1100 XLT

When looking at the brighter stars I cannot focus them to a sharp image. They appear fuzzy. Image of a star test on Vega attached (taken with a Watec 120N webcam). Diffraction rings are sparse and mottled. Does not really indicate that scope needs collimation. Can you help please.?


Mike Brightmore

Posted by on

  • Anonymous Dec 20, 2008


    All objects seem out of focus no matter how I adjust the focus knob.

    The images of stars look similar to your picturs. The moon's craters can be seen, but they do not have the sharp definition I was used to with other telescopes I have used. I was told that this could be an issue of the telescope needing to be collimated (sp?) correctly. I noticed that the stars are slightly tear drop shaped which leads me to believe that the optics are misaligned. How is this done? I had a reflector and the process was easy. How is it done on a Celestron Schmidt-Cassegrain?


2 Answers

  • Level 3:

    An expert who has achieved level 3 by getting 1000 points


    An expert that got 10 achievements.


    An expert that got 5 achievements.


    An expert who has answered 1,000 questions.

  • Master
  • 1,027 Answers

The image shows that the optics are not centered properly. The secondary may be tilted slightly to the 2 o'clock position. When not centered, a focused star will have an astigmatic shape, and not come to a full focus. Also check the mirror and corrector plate for dewing, that will also affect the views.

Posted on Nov 08, 2008

  • Level 1:

    An expert who has achieved level 1.

  • Contributor
  • 1 Answer

I have had the same problem, but when I got used to the collimation process and which way to turn the adjuster screws life has been much easier for photographing, usung a 7.5mm eye piece for adjusting the perfice circle.

Posted on Aug 20, 2010

Add Your Answer

Uploading: 0%


Complete. Click "Add" to insert your video. Add



Related Questions:

1 Answer

I have a Celestron C-90. When I turn the focus barre; it goes through focus but never getgs a sharp inage

Your friend may have dropped it, causing it to go out of collimation (optical alignment).
To test this, set it up outside and allow it about an hour to cool to the surrounding temperature. Then point it at a star of low to moderate brightness, and defocus slightly. You should see something like one of these images

If the rings are not concentric, shown in the bottom row, the scope needs collimation. These scopes were not meant to be collimated by the user, being glued together, so you will probably have to send it to Meade.
If concentric, as in the top row, it is OK. In that case, seeing conditions were just not good, or your lenses need a clean, or there was dew on them.

Apr 03, 2012 | Telescopes

1 Answer

Am I supposed to see the cross in the centre of image on celestron 76eq

You will see diffrection spikes when focused on a very bright object

and this can also appear around a bright planet. However it is very irritating, and to minimise it, make sure your scope is well collimated (optically aligned).

There is too much to collimation to include here, but there are many guides on the Net

Feb 22, 2012 | Celestron FirstScope 76EQ (180 x 76mm)...

1 Answer

Is there a fuse inside a CPC1100?

Yes and several circuit boards-- usually but not always-- any electrical issues are on the BOARDS and not the fuse.

Time to return it to Celestron- call them for tech advice here--

Jul 29, 2011 | Celestron CPC 1100 GPS (XLT) (70 x 280mm)...

1 Answer

Need to replace GPS module on celestron CPC 1100 xlt. Where can I find this part? Thanks

Contact Celestron at this web site-- best to call them--

Jul 29, 2011 | Celestron CPC 1100 with Standard Coatings...

1 Answer

When I look in all I see is my eye??

Did you put an eyepiece into the focuser? You are NOT in focus -- practice focusing during the day time on a distant object. TURN the focusing knob to either the left or the right until you get a sharp image.

Jan 19, 2011 | Celestron AstroMaster 114 AZ (50 x 114mm)...

1 Answer

I have a new Celestron 114M Newtonian telescope that when trying to look at Jupiter all I see is a smear of light and when I focus in I see the black cross bows of my telescope on top of a bright white...

USE only the eyepieces do not use the 2x barlow. Try again with just the eyepieces starting with the one with the largest number written on it. Focus slowly until you get a sharp image-- you can practice during the day time on a distant object.

Read my tips on my profile page.

Jan 10, 2011 | Celestron Telescopes

1 Answer

I just purchased a Celestron 127MM reflector AstroScope telescope, for my son. He assembled the scope, put on the 39mm. eye piece on the telescope, and know he says is "all I see through the eye piece is...

It is NOT in focus.

Take the scope outside during the daytime and practice focusing on a distant object. Turn the focusing knob until you get a sharp image in the eyepiece.

Aug 30, 2010 | Celestron PowerSeeker 127 EQ 21049 (750 x...

1 Answer

Obscured view through telescope

You can slow down dew forming on the mirror by NOT pointing the telescope toward the sky during cool-down-- just leave it parallel to the ground. Same goes for your eyepieces -- leave them covered, or inside a case.

Dec 26, 2008 | Celestron AstroMaster 130EQ Telescope

Not finding what you are looking for?
Telescopes Logo

Related Topics:

891 people viewed this question

Ask a Question

Usually answered in minutes!

Top Telescopes Experts

Joe Lalumia aka...
Joe Lalumia aka...

Level 3 Expert

3185 Answers

Geoffrey White
Geoffrey White

Level 3 Expert

3961 Answers

kenneth njonjo

Level 3 Expert

1575 Answers

Are you a Telescope Expert? Answer questions, earn points and help others

Answer questions

Manuals & User Guides