Help needed with my new Pegasus Astro NYX-88 mount, also an issue with calibration

[Philippe ANGERS]

Hello,

I've aquired an RC 6 and assembled an optical chain made of an OAG Zwo Large, with a ToupTek GPCAM 662M, a Zwo mini filter wheel and a Zwo ASI 183MM Pro.

I'm using my mount on a robust AZ EQ 6 tripod, and I'm connected to my mains.

Yeserday and the day before there was no wind, my sky is Bortle 5.

I use a Mele 4C N150, 16 GB and 512 SSD, with Windows 11 Pro up to date, and NINA v3.2 as well as PHD2 v2.6.14.

Focal length and camera pixel size have been adjusted to the exepected values.

I do 3 or 4 Polar alignements with TPPA from NINA and stop at less than 1' of precision.

Then I use the caibration assistant and let it manage the slew and just press "Calibrate".

I've been doing this many many times as I also have an observatory with an AZ EQ6 and some other setups, and among them an RC 8 !

But I've spent more than a month trying desperately to calibrate, and all of my calibrations ended with the same error message and all of them failed .

Here's the link to the zip files of my last 2 nights :

- https://openphdguiding.org/logs/dl/PHD2_logs_GhB2.zip

You can also take a look at a video I did about one among many failed attempts and I defintely consider the behaviour of trhe mount really weird :

-  https://drive.google.com/file/d/1ubKmo8_epWiiT9ZFtj6-ALDbugLXdDQL/view?usp=drive_link

Beware, the first night I was using the RC 6 with my optical chain WITHOUT the CCD47, and last night I had installed the CCD47 and spent a long time finding the focal distance, therefore, this is not an error of figures regarding F/L and F/D !

I went so far to find out if it was the focal length or F/D that was at the origin of my issue.

Pegasus support has no real explanation and tells me the mount is ok, and that I probably did something wrong...

They advised, in one last message to just increase calibration steps from 12 to 16 or 20 and that would make it, what it didn't...

Thanks for your help

Philippe

[Bruce Waddington]

Sorry, this seems like quite a mess, I don't think we can do much with it.  To make any progress, I think you need to be getting better quality guide camera images for PHD2 to work with.  Start by doing this:

1.  Work to get a better focus on the guide camera.  It's regrettable that the camera can't be binned, guiding at 0.65 arc-sec/px is going to be challenging.

2.  Fix the saturation-adu setting in PHD2.  Even though the camera may use 12-bit electronics internally, the data returned by the driver is being scaled to 16-bit (a good thing).  So your saturation level is actually 65K, not 4K.  That said, it really looks to me like the camera isn't well-focused - the stars are too large and faint.  Also, turn off the star-mass-detection feature in PHD2.

3.  Leave your mount guide speed at 1.0x sidereal and don't fiddle around with it while trouble-shooting

4.  Get a measurement baseline using the attached procedure.  In addition to what's in that document, get a 20-minute guiding session on each side of the pier without a bunch of lost-star events.  And don't fiddle around with any of the guiding parameters.

Looking ahead, I thing you are probably right about the mount having problems.  The inability to get a clean calibration is a definite pointer in that direction.  Here's just one example (RA in red, Dec in green):

You can see the RA axis isn't moving smoothly or consistently during calibration.  The 3 arrows to the left point to times when the data points are bunched up and the axis isn't responding well.  The arrow to the right shows the Dec points wandering around because of what is probably a large amount of periodic error in RA.  But until you can get a cleaner dataset with longer periods of guiding, we can't say much more.

Good luck,

Bruce

[Philippe ANGERS]

Hello Bruce,

Thank you so much for your quick analysis!

I do know this is a mess, I've tried only to calibrate, therefore almost no data is available regarding true guiding attempts! :-(

May I ask your a few explanation regarding your reply, just to be sure I got it right!?

1 - Better focus : I'm using a ToupTek GPCAM 662M with an I.R filter and tried focusing as best as I could with the helicoidal focuser and I find it hard to geta better result, but mayb I could...

2 drivers exist one is labeled '"ASCOM" but produce weir result, and I used the second one, not quite sure of the difference but the background is not very clear !

You said : "It's regrettable that the camera can't be binned, guiding at 0.65 arc-sec/px is going to be challenging" : I can ! I mean I didn't choose to do it, thinking it would be ok witout it, but unless the camera doesn't allow it, I can and will BIN to 2 if it can help!!!

I'll apply anything required to get out of this mess !!!

So do you advise me to BIN to 2 ?

2 -  Fix the saturation-adu setting in PHD2 : what do you mean ? Should I change the value I simply computed for the 12 bits depth at 4 095, and change it to 65 535 or leave it as is??

3 -  Leave your mount guide speed at 1.0x sidereal : you mean the guiding speed from my mount ? I don't remmeber having change this i PHD2, if so I did it accidentally, where would it be located in the menus if so?

Thanks for your confirmation

Philippe

[Brian Valente]

Philippe

here are my own clarifications 

1 - Better focus : yes, try to focus the camera better. You may also try without the IR filter just to confirm it isn't the filter itself. 

2 drivers exist one is labeled '"ASCOM" but produce weir result, and I used the second one, not quite sure of the difference but the background is not very clear. Not sure what drivers you are referring to, maybe you can clarify? What do you mean by "produced weird result"? ASCOM should work fine here, but specific driver is not critical if the camera is working. Make sure the camera and ascom driver are both up to date.


So do you advise me to BIN to 2 ? Yes, if it can be binned, bin 2

2 -  Fix the saturation-adu setting in PHD2 : set it to 16 bit or 65,535. 

3 -  Leave your mount guide speed at 1.0x sidereal : you mean the guiding speed from my mount ? I don't remmeber having change this i PHD2, if so I did it accidentally, where would it be located in the menus if so? In other words, don't experiment with the guide speed, leave it at 1.0x

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Brian Valente

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[Philippe ANGERS]

Hello Brian,

Thanks very much for all these clarification.

I'll indeed test with and without the IR filter.

I chose a ring corresponding specifically to this ToupTek camera and some other brands with the same standards.

But as said, windows in PHD2 are way too small, even enlarging it to finetune focus.

Usually, I open ToupSky which is an app just like Zwo's ASI Studio and I can enlarge, set precisely the settings.

And visually, I had the feeling that it didn't change that much regarding the few stars available when trying to do it.

Sometimes I get a gull wings shape, sometimes something more or less round, the cam is locked by a couple of screws on the helical focuser pressing the body and the resulting shape of satrs is very sensitive to this...

Regarding the ToupTek drivers, a few more explanation : if you install the lastest drivers available (2025), you can select between 2 versions of the driver :

- ASCOM ToupTek Camera

- ToupTek Camera

The first one looks more detailed with many options that can be set (see joined file named "G3M662M(USB2.0)", while the second just offers the possibility to select between 8 or 16 bits (see file joined named "ToupTek Camera") !

I also join the PHD 2 dropdown menu to select the camera but the second choice being way down the list cannot be seen at the same time...

ToupTek support urged me to use the first one  when I asked them which one was advised, but, the background was very clear, very grainy, I could hardly distinguish stars flooded in this "soup" even setting the display with the rulers in PHD2!

Therefore I soon decided to use the second one, and I got back a more common, slightly grainy background!

The point is, that in between, I had discovered that getting rid of a calibration attempetd with it, noticeably improved the quality!!

Very surprising, a coincidence, I don't know, but I never got back to this driver since then...

But i could give it a new try!

I'm open to any other advice ! :-)

Philippe

[Tom van Peer]

I use that same Touptek camera with an IR pass filter and the Ascom driver without issues. But I have the gain set at 0, not 45, and I use 16 bit. If you want to focus better, don't use the display of the camera but the Star Profile tool, as suggested in the documentation.

[Philippe ANGERS]

Hello Tom,

Thanks for this feedback!

So if you can use it with this driver, I will try again, and indeed set the gain to 0 (I didn't dare try this back then).

And of course select 16 bits.

I'll also use the star profile and find out if I was that far from the optimal setting...

Philippe

[Philippe ANGERS]

Hello,

@Brian Valente : I didn't remember, but selecting again the ToupTek ASCOM driver, I realized  that something was very annoying, reason why I gave up this driver, don't know how you came around this, but I can't change the camera gain as the field is grayed out in PHD2 !

Taking  a look at the image when the camera is connected, there's a very grainy image and of course you can't distinguish stars and faint stars :

And I can't change anything, even though I set to "0" in the ASCOM driver, it doesn't make any difference !

How did you do ??

Philippe

[Brian Valente]

Philippe

You should contact ToupTek for questions about their camera driver. The camera driver is shown in PHD, but it is provided by ToupTek.  They may have recommendations on settings for guide cameras. 

the one thing you can control in PHD is the visibility gain slider, but that is only for visual appearance, it does not alter the data.

Brian

To view this discussion visit https://groups.google.com/d/msgid/open-phd-guiding/91d41c78-dc9c-472c-843c-9e41337eba4dn%40googlegroups.com.

[Philippe ANGERS]

Hello,

I did, but they were unable to help me, they didn't give any explanation when I asked them how to go around this issue...

Support is less reactive and high level compared to Zwo or Player One or ToupTek...

Philippe