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Autoguider guide scope and tracking question

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#1 bananaheim

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Posted 19 October 2013 - 07:08 AM

I recently purchased an orion starshoot autoguider to replace the celestron Nexguide autoguider. I have had some limited success with the orion, but mostly when I start to track the green box in PHD follows the star during calibration but losses it shortly thereafter. The scope is polar aligned within a few degrees and I am using Starsense for alignment if that matters. I am using the guide scope that came with the Nexguide (Celestron 80mm Guidescope with 600 mm (23.62 in) Focal Length with 7.5 Focal Ratio) rather than buying the one that comes with the Orion starshoot (80mm f/5.0). I am wondering if others have used this Celestron guide scope with the Orion starshoot and if so have the changed the settings in PHD?

Also, I was looking at the tracking setup in my scope (CGEM DX 1100 HD) Does the tracking setup there matter? Right now I have it set to "sidereal tracking" and "RA only", but I noticed there is an option to change "sidereal" to "disable" or change "RA only" to "RA and Dec." Does that matter? Is there a "correct" setting when imaging and using an autoguider?

Any help would be appreciated!

Steve

#2 rigel123

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Posted 19 October 2013 - 10:09 AM

I recently purchased an orion starshoot autoguider to replace the celestron Nexguide autoguider. I have had some limited success with the orion, but mostly when I start to track the green box in PHD follows the star during calibration but losses it shortly thereafter. The scope is polar aligned within a few degrees and I am using Starsense for alignment if that matters. I am using the guide scope that came with the Nexguide (Celestron 80mm Guidescope with 600 mm (23.62 in) Focal Length with 7.5 Focal Ratio) rather than buying the one that comes with the Orion starshoot (80mm f/5.0). I am wondering if others have used this Celestron guide scope with the Orion starshoot and if so have the changed the settings in PHD?

Also, I was looking at the tracking setup in my scope (CGEM DX 1100 HD) Does the tracking setup there matter? Right now I have it set to "sidereal tracking" and "RA only", but I noticed there is an option to change "sidereal" to "disable" or change "RA only" to "RA and Dec." Does that matter? Is there a "correct" setting when imaging and using an autoguider?

Any help would be appreciated!

Steve


If you are truly within a few degrees on your polar alignment I would think you need to be quite a bit closer to allow the guider to do its job. That would be a lot of movement for the guider to correct for. If you meant minutes of degrees within alignment that's a different story. It could be losing the star if your exposures are too short, seeing is extremely bad, etc. Also make sure it is a star you are locking on and not a hot pixel, that has happened to many of us as well.

What are your settings in PHD?

#3 bananaheim

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Posted 19 October 2013 - 10:29 AM

I'm using 1 of 2 second exposures and the default settings (see screen shot). The seeing conditions are good for Orange County California. I've done the hot pixel dance before, so I'm avoiding them now. I meant minutes of degrees. Do I need to change the defaulting settings for the type of guide scope perhaps?

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#4 fmhill

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Posted 19 October 2013 - 10:48 AM

Hi Steve,

I have been through the exact same situation you are going through and that I have a CGEM DX mount and that I originally purchased a Celestron Nextguide, and after being frustrated by it, I purchased the Orion SSAG guiding camera which I use with a Celestron 80 mm guide scope very successfully. It's a much better system than the Celestron Nexguide autoguider setup. I use this auto guiding system very successfully on a couple of different mounts.

1st of all in the mount settings you want both RA and DEC guiding enabled and you should use the Sidereal tracking mode, you don't need to change any settings from the default settings in mount control. But you do need to change the settings in PHD.

In PHD, sets RA aggressiveness to 100, Max RA to 250, Max DEC to 1000, RA hysteresis to 50. Be sure to select a star for calibration that is below 60° declination.

I will private message my email address so that we can exchange PHD log files, screen captures of the parameter settings, and images so that I can analyze and advise you as to adjustments that may be needed

The Orion Star Shoot Auto Guiding works very well for me with the Celestron 80 mm guide scope, and I think you will be very happy with this 2 once we get your parameters set so it's working for you.

I'll be very glad to help you work your way through getting this working as expected

#5 Aquarist

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Posted 20 October 2013 - 04:31 AM

Wow, Mitch (fmhill) what a great informative post! Very well done!!!!

#6 rigel123

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Posted 22 October 2013 - 02:59 PM

My settings are a little different when guiding with my 80mm, RA Aggressiveness = 95
RA Hysteresis = 10
Min Motion = .25
Depending upon the area of the sky I would increase the Calibration Steps so that you get calibration in about 10 - 12 steps. With the 80 mm I have that on 2500, nearer the pole I decrease them.

I also run my gain around 50%.

#7 GlennLeDrew

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Posted 22 October 2013 - 05:45 PM

My potential concern is this. You state a polar alignment to within a few degrees, but are applying corrections in RA only. Might the fairly rapid declination drift induced by your not-close polar alignment be the cause if the problem? (A friend has the SSAG, but I've had no need to look into the details of the PHD software, as his setup using default settings worked just fine the first time in use.)

#8 tomcody

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Posted 22 October 2013 - 06:03 PM

A lot of " loosing the guide star" problems are caused by using a too dim guide star or having high level clouds cross in front of the guide star and loose the lock for a few seconds.
Before changing a lot of settings, I suggest you try guiding on a very bright star on a clear night. If it tracks? you have one of the above issues and you can adjust the exposure setting as needed.
Rex

#9 Sniemiec

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Posted 23 October 2013 - 06:59 AM

I have just started using the Orion StarShoot auto guider. I have several nights of fun setting up on an old Meade 2080 OTA, that I mounted on a new Celestron AVX mount. But that is another story.

I found exactly the same issue. But then I looked at the numbers at the bottom of the PHD window. They seemed to be displaying the guide pulse duration. Both RA and DEC.

I checked the settings, and found the pulse duration was almost always the same as the maximum set in the settings panel.

I kept on increasing the Max Duration until the guide pulses were not all reaching the max. It worked!

Not pretty. But for a test of the gear it was impressive. With only a planetary align on Venus, and no alignment stars. I was able to get 5 min subs with no trailing! :) :)






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