Initial Settings with a Scope on a Wedge

[Rick Eisenmann]

     I would like to try some guiding tests with PHD2 and I am looking for some suggestions on the initial settings to start my tests. I have a Celestron Evolution 8 on a wedge.

     I have read quite a few posts in this forum and have done some google searches but I am still not sure what values I should start with. In particular, there are three areas that I believe will have the biggest impact on my tests (assuming I have taken care of the basics - level tripod, balanced scope, no cord wrap, etc).

     1) In PHD2, in the Advanced Settings - Algorithms, can you tell me what algorithm you would suggest for Right Ascension and Declination (I think I should start with Hysteresis - Lowpass2)?

     2) Also in PHD2 in the Advanced Settings - Algorithms, should I have Backlash Compensation Enabled and if so, to what Amount?

     3) On my mount, from the Hand Control, under Menu - Scope Setup - Anti Backlash, there are 4 settings for backlash (Azm Positive, Azm Negative, Alt Positive and Alt Negative). Should I have all of these set to Zero or should I test different values for any/all of them?

I realize there are other parameters in PHD2 that I will need to adjust but are there any other parameters that I need to pay "special attention" to when using a wedge?

Thanks for your help,

Rick

[bw_m...@earthlink.net]

There is nothing special about using a wedge with PHD2.  With the scope mounted on a wedge, its right ascension axis will point at the celestial pole, just as it does with a German equatorial mount. You should follow all the usual instructions for getting started with PHD2 – start by running the new-profile-wizard being careful to provide correct values for the properties the wizard asks about.  Make sure the guide speed in the mount is at least 0.5x sidereal.  Disable all backlash compensation features in the mount controller and leave them at zero. Then leave things alone, the wizard will set the guiding properties to values that should deliver reasonable results.  Leave the algorithm choices and everything at their default values.  Fiddling around with the guiding parameters is only done to counteract peculiarities and weaknesses in the equipment, and until you know exactly what those are, there is no basis for changing anything. 

 

It’s important to study the User Guide and the various support documents like ‘Best Practices’.  You will need to get a good focus on the guide camera, a reasonable physical alignment of your mount on the celestial pole, and a reasonable calibration of the guiding system.  When those basics are mastered, you can move on to run the Guiding Assistant and start to get a feel for how well your system can track with no assistance from guiding.  That is where things like backlash compensation and other settings will come into play – but the Guiding Assistant will help you to make those adjustments.

 

Documentation:

https://openphdguiding.org/documentation/

 

Best practices:

https://openphdguiding.org/phd2-best-practices/

 

Measuring baseline mount performance:

https://www.dropbox.com/s/zrf0au7jaisvt85/How%20to%20create%20a%20baseline%20for%20guiding%20results%20using%20OpenPHD2.pdf?dl=0

 

Good luck,

Bruce

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[Rick Eisenmann]

Thanks for the quick reply Bruce!

As soon as we get a clear night I'll give it a shot.

Rick