Jump to content


Photo

Problem with CG5 Dec

  • Please log in to reply
8 replies to this topic

#1 Domerman

Domerman

    Just Lucky, I Guess.

  • *****
  • Posts: 1331
  • Joined: 21 Jul 2007
  • Loc: PA

Posted 06 July 2009 - 02:45 AM

The dec on my CG5 appears to be out of whack. Several months ago I received a brand new CG5 which operated wonderfully out of the box. I was able to get longer than 20min subs with my 80ED and CG5 combo... and of course PHD guiding. Now, for whatever reason, PHD shows major fluctuations in my dec tracking. The tracking in the RA is still very smooth and easily guided out, but not so in dec. Everything is drifting severally south in dec. I use the all star polar alignment routine with the CG5 and using this same routine with the same scope several months ago, I was able to take 20 min subs with ease. For some reason now, I can only take 10 minute subs, but that is exceedingly rare now. Often, I have issues even taking two minute subs. My setup is very well balanced in both RA and dec (and light weight even for the CG5), so I don't believe balance is an issue. Also, the mount is powered by an outlet coming from my house, so power is not an issue either. Anybody here can help me with the problem? :confused:

#2 rmollise

rmollise

    Hubble

  • *****
  • Posts: 15688
  • Joined: 06 Jul 2007

Posted 06 July 2009 - 07:04 AM

The dec on my CG5 appears to be out of whack. Several months ago I received a brand new CG5 which operated wonderfully out of the box. I was able to get longer than 20min subs with my 80ED and CG5 combo... and of course PHD guiding. Now, for whatever reason, PHD shows major fluctuations in my dec tracking. The tracking in the RA is still very smooth and easily guided out, but not so in dec. Everything is drifting severally south in dec. I use the all star polar alignment routine with the CG5 and using this same routine with the same scope several months ago, I was able to take 20 min subs with ease. For some reason now, I can only take 10 minute subs, but that is exceedingly rare now. Often, I have issues even taking two minute subs. My setup is very well balanced in both RA and dec (and light weight even for the CG5), so I don't believe balance is an issue. Also, the mount is powered by an outlet coming from my house, so power is not an issue either. Anybody here can help me with the problem? :confused:


Ok...firstly, how good is your polar alignment? Check for declination drift. If that's not good, tighten up with a drift alignment. Can you describe how you are doing the alignment? If you are off enough, PHD will not be able to keep up.

Suspect 2 is PHD. check/verify your setup. If you are guiding through the Autoguide port, doublecheck your ST4 cable. Have you changed any settings? Computer changes? Are you shooting in a different part of the sky than you used to? If you are using ST4 style guiding, there is a small chance the problem is your guide port. Can you move the scope in declination manually from the computer using your guide program (or Shoestring's port checking program)? What's the guide rate setting in your HC?

DO NOT discount power as a problem. These mounts are very sensitive in that regard. I suggest you try the mount with a 12 volt BATTERY.

Final suspect (and probably the least likely) would be the declination axis. Will it respond normally to HC button presses?

#3 wsuriano

wsuriano

    Vostok 1

  • -----
  • Posts: 146
  • Joined: 13 Nov 2007

Posted 06 July 2009 - 10:17 AM

What version of PHD are you using? Did you recently upodate the version? Some have recently reported problems with the most recent versions of PHD guiding in DEC. You can check it out by joining the Stark-Labs group on Yahoo. If you have a recent version, try going back to version 1.8.2 and see if the problem persists.

#4 Domerman

Domerman

    Just Lucky, I Guess.

  • *****
  • Posts: 1331
  • Joined: 21 Jul 2007
  • Loc: PA

Posted 06 July 2009 - 10:38 AM

Where can I download the older version of PHD?

#5 wsuriano

wsuriano

    Vostok 1

  • -----
  • Posts: 146
  • Joined: 13 Nov 2007

Posted 06 July 2009 - 01:13 PM

Steve:

Craig posted them at:

http://www.stark-labs.com/OldVersions

Bill

#6 Domerman

Domerman

    Just Lucky, I Guess.

  • *****
  • Posts: 1331
  • Joined: 21 Jul 2007
  • Loc: PA

Posted 06 July 2009 - 02:50 PM

Ok...firstly, how good is your polar alignment? Check for declination drift. If that's not good, tighten up with a drift alignment. Can you describe how you are doing the alignment? If you are off enough, PHD will not be able to keep up.


As I said the first time around, the alignment is done using the all star alignment routine which has been perfect before. Drift align is really not necessary with a scope that has a focal length of 480mm. I was able to get 20 min subs easily before.

Suspect 2 is PHD. check/verify your setup. If you are guiding through the Autoguide port, doublecheck your ST4 cable. Have you changed any settings? Computer changes? Are you shooting in a different part of the sky than you used to? If you are using ST4 style guiding, there is a small chance the problem is your guide port. Can you move the scope in declination manually from the computer using your guide program (or Shoestring's port checking program)? What's the guide rate setting in your HC?

I guide through the HC using ASCOM drivers. I can control the scope manually through the computer in both dec and RA.

DO NOT discount power as a problem. These mounts are very sensitive in that regard. I suggest you try the mount with a 12 volt BATTERY.

Never had any issues before with the power. I don't have a battery to try with.

Final suspect (and probably the least likely) would be the declination axis. Will it respond normally to HC button presses?


Yes.


I might just have to accept that something is fatally wrong with the dec. Bummer.

#7 rmollise

rmollise

    Hubble

  • *****
  • Posts: 15688
  • Joined: 06 Jul 2007

Posted 06 July 2009 - 04:35 PM

As I said the first time around, the alignment is done using the all star alignment routine which has been perfect before. Drift align is really not necessary with a scope that has a focal length of 480mm. I was able to get 20 min subs easily before.


I asked about polar alignment because it sounds like you are drifting in dec. Never assume that what once worked still does. What do you think is going to cause constant drift in declination (if that is what you are describing) if not poor polar alignment?

How do you figure something is "fatally wrong" with the dec if it responds normally to the HC and the computer? Check your PHD settings AND YOUR PROCEDURE most of these things amount to PILOT ERROR, which can happen after you start feeling comfortable with the setup. ;)

I'd also recommend reseting the HC to factory defaults and re-entering your settings.

Don't forget to check the guide rate in the HC--that will apply to either serial or ST4 guiding.

#8 Domerman

Domerman

    Just Lucky, I Guess.

  • *****
  • Posts: 1331
  • Joined: 21 Jul 2007
  • Loc: PA

Posted 06 July 2009 - 09:45 PM

Perhaps with my all star polar alignment routine I am using a star that is too close to zenith. How far away should the star be from zenith, celestial pole, and the horizons to be good enough for use with the polar alignment routine?

#9 rmollise

rmollise

    Hubble

  • *****
  • Posts: 15688
  • Joined: 06 Jul 2007

Posted 07 July 2009 - 06:50 AM

Perhaps with my all star polar alignment routine I am using a star that is too close to zenith. How far away should the star be from zenith, celestial pole, and the horizons to be good enough for use with the polar alignment routine?


Don't use a star at zenith. Use one to the south, about at the point where the celestial equator and meridian intersect. You can also use Polaris with AllStar--I've done that quite successfully.






Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics