Guiding a Mach 2 in PHD2 ( and NINA)


Andrea Lucchetti
 

Hello,
I had to quickly move to NINA because my skyx doesn't cooperate well with APCC Pro after 1.9.

I almost used the standard setting in PHD2 and saved the night but guiding was bad.
I noticed the corrections were 4 times the magnitude of the reported errors.
in skyx I have values suggest by Roland in the past and they worked well:
-minimum move:0,03 sec
-maximum move:0.2 sec
-delay after correction:0.1 sec
-simultaneous corrections: off

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?

Thank you very much,
Andrea


ap@CaptivePhotons.com
 

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.

 

Linwood


Andrea Lucchetti
 

Thanks Linwood,
very helpful.

Yesterday I was in hurry and very lucky to understand the basics for saving the night, the calibration happened almost by chance as I couldn't find a calibrate button :-)
will try the assistant.
I was lucky with some setting, flip worked nicely and I used the same setting you have for "reverse DEC after meridian".
If I got it, I can run the calibration before the sequence in PHD and NINA will recognize it and use it, or clear calibration before the sequence and NINA will take care of this in the sequence but at the target DEC.

I would be grateful if you can point me to the advanced sequencer that I couldn't find.

The direct guide setting I am referring to is in NINA Options- equipment- guider setting section. I think it is related with dithering only but I don't understand it.

Thank you
Andrea


ap@CaptivePhotons.com
 

Andrea Lucchetti wrote:

 

  • Yesterday I was in hurry and very lucky to understand the basics for saving the night, the calibration happened almost by chance as I couldn't find a calibrate button :-)
    will try the assistant.
    I was lucky with some setting, flip worked nicely and I used the same setting you have for "reverse DEC after meridian".
    If I got it, I can run the calibration before the sequence in PHD and NINA will recognize it and use it, or clear calibration before the sequence and NINA will take care of this in the sequence but at the target DEC.

    I would be grateful if you can point me to the advanced sequencer that I couldn't find.

    The direct guide setting I am referring to is in NINA Options- equipment- guider setting section. I think it is related with dithering only but I don't understand it.

 

So first: NINA has three versions, released, beta and preview/nightly.  The advanced sequencer is only in the nightly.  It’s under rapid development, a new version every few days, and occasionally has some issues, but I and many other find it stable enough to use. Each need to decide on their own tolerance for stability.  But all the new fancy stuff is there.  It can also convert basic sequences to advanced.

 

The advanced sequencer is a drag-and-drop “programmer” for your sequence, whereas the basic sequencer in the beta and released is more of a declarative one – you tell it what to do, and it figures out when.  For example you can tell it to auto focus after meridian flip and it will, but in the advanced sequencer you can also just stick in a step that says “auto focus now” (you can still AF after flip as well, or AF after HFR change, or AF after filter change, etc.).   But it brings in concepts like “loop until nautical dawn” or “wait until target altitude above X”.

 

I’m guessing the direct guide you are seeing is only in an older version.  Or you are connecting to the Direct Guider “equipment” which is a way you can dither on a mount without actually having a guider, it just periodically moves the mount.   I don’t have an old version handy to see what it shows.

 

Calibration only needs to occur if something changes in the imaging train to affect image scale or rotation, or maybe in a gross sense polar alignment though small difference there should not matter.  If you have a semi-permanent setup, where everything stays the same, you can set PHD2 to restore the prior calibration each time it starts.  If not set, or if you change other things (rotation being my main issue) you need to recalibrate.  You can do that with just s shift click on the green guide button.  Or it happens automagically if you didn’t restore as soon as you start guiding.

 

I used TSX with my MyT.  I am VERY glad to let it go now that APCC 1.9 supports NINA.  TSX has some incredible features, but it also has some ancient software paradigms that to me make it flakey, and weighed down with a lot of baggage.  It’s just not needed with APCC IMO, now that NINA can control the camera.

 

Oh… The new sequencer also supports plugins which include a Three Point Polar alignment that is very fast, and very accurate (especially since Ray fixed MoveAxis, thanks!), much easier than Sharpcap or Pempro.   So one less need to step outside for another tool.   There’s also some APCC specific stuff, notably supporting counterweight up flips, but I have not used it – I find flipping at transit is simple and safe and just plain works.

 

Linwood

 


Andrea Lucchetti
 

Linwood, thank you.
I agree on skyx vs NINA. I run for years a PME with skyx and CCDAP so my first instinct has been to just continue.
I was studying NINA in the background, yesterday I had to step to it to save the day. It worked (almost) at the first run.
Now I have a nomad set up that can use on average every two months, so I am worried about beta or similar (nightly?).

if I got it, with the advanced scheduler I could also do things such as "Focus now" and "plate solve and sync".
I am finding these are very helpful in the field if something doesn't work as expected.
Andrea 


ap@CaptivePhotons.com
 

With the exception of plate solving (well, mostly) and focus, you can do almost anything else inside in daylight with the real mount hooked up to experiment.  There’s a simulated camera which will download sky survey images for your coordinates, so even plate solving sort of works (though I had trouble using it with APPM for reasons unclear, whereas real images worked fine).

 

I found this particular useful for testing meridian flips, since you can just do them over and over to check.

 

I get the worry about the nightly version.  I’ve been pleasantly surprised how stable it is, but of course the first time out with it, it may fail you.  Doubtful, but always possible.  Each has to decide.

 

 

From: main@ap-gto.groups.io <main@ap-gto.groups.io> On Behalf Of Andrea Lucchetti via groups.io
Sent: Sunday, September 12, 2021 4:40 PM
To: main@ap-gto.groups.io
Subject: Re: [ap-gto] Guiding a Mach 2 in PHD2 ( and NINA)

 

Linwood, thank you.
I agree on skyx vs NINA. I run for years a PME with skyx and CCDAP so my first instinct has been to just continue.
I was studying NINA in the background, yesterday I had to step to it to save the day. It worked (almost) at the first run.
Now I have a nomad set up that can use on average every two months, so I am worried about beta or similar (nightly?).

if I got it, with the advanced scheduler I could also do things such as "Focus now" and "plate solve and sync".
I am finding these are very helpful in the field if something doesn't work as expected.
Andrea