Re: Guiding a Mach 2 in PHD2 ( and NINA)

Andrea Lucchetti wrote:


  • I'll be very grateful if you can share PHD2 settings for AP mounts and Mach2 in particular (algorithm, settings, etc).
    Also, For NINA Users:
    -(Dale, if you see the message), in NINA there is a parameter called "direct guide duration" that was preset at 2 and I don't know if it must be changed and how.
    -the calibration in PHD must be done before the sequnce start or NINA wait for PHD calibrating, so Idon't do anything in PHD?


I’m not Dale, but I would suggest a couple things.


In PHD2, if  you didn’t, it is useful to run the wizard to create the profile, then slew high and near DEC 0 and calibrate, then run the guiding assistant and consider its recommendations.  It may not recommend algorithms however, if you go to the that tab I’ve found that the less aggressive algorithms work best since the AP mounts track very well; I use lowpass2 for both RA and DEC.


Guiding assistant will also check backlash in DEC, which I would assume is near zero, and on that same tab you probably want backlash compensation off (if it doesn’t say it is near zero, on a mount with encoders, something else is going on).


I have found it does not matter much if I use short (say 2s) or long (7s) guide period/exposures, it just works, but generally if you can long is better especially if seeing degrades since otherwise you can chase seeing.  Experimentation is needed there.  I do set it to 1s for calibration just so it is faster to calibrate, then reset for later.  On the AP1100 you do not want “Reverse DEC after meridian”, I assume the same on the Mach 2.


Calibration in NINA is a bit clunky if you want to calibrate somewhere other than your target, and you might want that if the target is too low at the start of the evening, or is at too high of a DEC angle.   It’s always best to calibrate at low DEC and high altitude, provided the low DEC is not too low in altitude for your latitude.  So rarely am I calibrating on my actual target, which is why I say it is a bit clunky in NINA.


So what I do is find a target high in altitude and as low DEC as I can, slew to it, plate solve to ensure I’m at the right rotation, set exposure (in PHD2) to 1s and calibrate.  Once I’m happy with calibration I go back to NINA for everything else.  I’ve also written sequences to do all this in NINA – in Sequence 2 you can – but you have to customize the calibration script to match the rotation of your eventual target.  I find it easier to just do by hand as part of the setup, it takes much longer to describe than to actually do.   I also calibrate each night even if I do not move my imaging train because I tear down and set up each night, and “did not move” is sometimes a surprise in that process.   So in PHD2 I turn off its memory of calibration (Guiding tab, auto-restore).


That said, if PHD2 calibrates inside NINA then NINA should wait.  In the advanced sequencer there is even an instruction to force calibration (you might need that if you have an electronic rotator for example, as you would need to calibrate after rotation).


Direct Guider is something else, it’s not part of PHD2 to my knowledge. 


Take all with a grain of salt, despite having the mount for 2 months it’s been outside only about 5 times due to weather.



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