Jump to content


Photo

Nexstar 8SE mount GO-TO alignment is inaccurate

  • Please log in to reply
7 replies to this topic

#1 Shaunavon

Shaunavon

    Explorer 1

  • *****
  • Posts: 56
  • Joined: 13 Jul 2013
  • Loc: Wauwatosa, WI, USA

Posted 10 October 2013 - 10:39 AM

Hello,

I have a used Nexstar 8SE Alt/Az mount which lacks accuracy regardless what alignment method is used. I tried the Solar System, SkyAlign (3 stars), Two stars and North EQ alignment methods and after alignment the GO-TO is far from locating the object. For example, if I enter M31 the mount slews and stops at Sirrah in Pegasus. If I enter the Moon or Venus it goes south of its intended object. The mount is level and the OTA is attached properly. I think this mount is ready to be boxed up and bury 6 ft under. Does anyone have any suggestion/s on making this mount usable. It is frustrating to take this mount to a public night event and cannot rely on it when lots of people standing nearby waiting on you to find DSO to see.

#2 WarmWeatherGuy

WarmWeatherGuy

    Surveyor 1

  • *****
  • Posts: 1886
  • Joined: 27 Aug 2011
  • Loc: Orlando, FL 28° N, 81° W

Posted 10 October 2013 - 01:40 PM

Try the auto 2-star align. Use Polaris as the first star and let it pick the second star.

If you don't have an eyepiece with a crosshair reticle then try defocusing the star so it becomes a large doughnut. This will allow you to more accurately center the star in the eyepiece which should result in more accurate alignment.

You might want to check out the NexStar forum. There are lots of pros there with answers.

http://www.cloudynig...0/Board/nexstar

#3 rmollise

rmollise

    Hubble

  • *****
  • Posts: 15373
  • Joined: 06 Jul 2007

Posted 10 October 2013 - 04:36 PM

Hello,

I have a used Nexstar 8SE Alt/Az mount which lacks accuracy regardless what alignment method is used. I tried the Solar System, SkyAlign (3 stars), Two stars and North EQ alignment methods and after alignment the GO-TO is far from locating the object. For example, if I enter M31 the mount slews and stops at Sirrah in Pegasus. If I enter the Moon or Venus it goes south of its intended object. The mount is level and the OTA is attached properly. I think this mount is ready to be boxed up and bury 6 ft under. Does anyone have any suggestion/s on making this mount usable. It is frustrating to take this mount to a public night event and cannot rely on it when lots of people standing nearby waiting on you to find DSO to see.


Likely pilot error...but maybe not. When symptoms like these appear and you are SURE you are doing the alignment correctly, do a factory reset in the hand controller.

I assume...

You are doing final centering with the up and right keys.

You are centering the CORRECT stars.

You are using a medium power eyepiece.

#4 mclewis1

mclewis1

    Thread Killer

  • *****
  • Posts: 10742
  • Joined: 25 Feb 2006
  • Loc: New Brunswick, Canada

Posted 10 October 2013 - 06:17 PM

In addition to Uncle Rod's great suggestions ...

- what type of power source are you using for your mount? If it's internal batteries get something more substantial, AA batteries don't last more than a few hours (and sometimes less when it's cold) and low power can cause exactly the symptoms you've described.
- have you read up on alignment tips and guidelines in the Nexstar forum?
http://www.cloudynig...4057680/page...

#5 Shaunavon

Shaunavon

    Explorer 1

  • *****
  • Posts: 56
  • Joined: 13 Jul 2013
  • Loc: Wauwatosa, WI, USA

Posted 10 October 2013 - 06:30 PM

Steve, Uncle Rod & Mark,

You have provided very promising ideas that may solve my problem. I do have my AA batteries in but my power tank is what I usually use. I will remove the batteries just in case they are not been used accidentally. In regards to the eyepiece, I usually start with my 25mm so maybe I should try with the 17mm or 10mm. I will try all your suggestions before attempting the factory reset. Tonight seems very cloudy but tomorrow night will be a better night to try all options.

I will inform you after all options have been exercised.

#6 Nippon

Nippon

    Viking 1

  • *****
  • Posts: 969
  • Joined: 22 Oct 2009
  • Loc: Central Florida

Posted 11 October 2013 - 01:51 PM

When you set up are you setting it up for daylight savings time or standard. This baffled me for at least an hour once right after a time change when we went back to standard after daylight savings. I would align, get an align success and all my gotos were off about 15 degrees.

#7 jrbarnett

jrbarnett

    Eyepiece Hooligan

  • *****
  • Posts: 19761
  • Joined: 28 Feb 2006
  • Loc: Petaluma, CA

Posted 12 October 2013 - 04:58 PM

Are you sure you're aligning on the stars indicated on the HC? Mistaking one star for another will kill your alignment every time. Also, are you carefully centering each alignment star (such as by using a reticle eyepiece)? Accuracy will be much better if each star is consistently centered during alignment.

Regards,

Jim

#8 Stelios

Stelios

    Surveyor 1

  • *****
  • Posts: 1971
  • Joined: 04 Oct 2003
  • Loc: West Hills, CA

Posted 12 October 2013 - 07:12 PM

Also, are you carefully centering each alignment star (such as by using a reticle eyepiece)?


Amen to that. I *thought* I could 'eyeball' it, but ever since starting to use an illuminated reticle EP, my GoTo's have gone from decent to totally sensational.

Uncle Rod's key advice of finishing the alignment with the UP and RIGHT keys (if seemingly not possible, go the other way and come back) is also something that is frequently overlooked.

As for time... it's still DAYLIGHT SAVINGS TIME, till first week of November.






Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics