Problem with autoguiding in PHD

[Wael Omar]

Hello,

I just bought Eq 35 skywatcher mount, I couldn't make any appropriate auto guidingfor a week till now. Problem First was that PHD didn't send any corrections to my mount although that my mount was connected to EQMOD succefully and I can move it with EQMOD BUT in PHD I couldn't. Today I discovered something that when I click on tracking option in the hand control of the mount the autoguiding starts but after a while it give significant deviation away from guide star until its lost.

This is the log for today:

https://openphdguiding.org/logs/dl/PHD2_logs_LsR5.zip

Please note that I made very precise polar alignment by sharpcap.

[Brian Valente]

Hello Wael

You main problem is that you have not gotten a good calibration, so you won't be able to guide until you do.

this is just one of the three examples of failed calibrations:

needless to say any resulting "guiding" is going to be terrible. here you have the two axis mirroring each other and speeding off to nearly 3000" deviation

I don't know which of your setup information or data is incorrect but it appears there is bad information in there, and the RA and DEC axis aren't calibrating correctly.

I recommend you start over with defaults and follow the baseline guiding carefully, do not change any of the defaults

https://www.dropbox.com/s/os1thorvswmzaul/How%20to%20create%20a%20baseline%20for%20guiding%20results%20using%20OpenPHD2.pdf?dl=0 

Until you can achieve a good calibration, your guiding results are not 

Also, i am not an expert in EQ series mounts, but I'm not aware of any mount where you can click a button on the hand controller and it triggers PHD software app to start guiding? Maybe I am missing something here

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Brian 

Brian Valente

portfolio brianvalentephotography.com 

[Wael Omar]

Hello Brian,

Thanks for your advice.

Below is recommendation after i used Guide assistant.

I apply it but still have bad guiding.

Let me say something , i tight the adjusting knob of the degree circles and also the lock of the RA and DEC axis in my mount so Is this having an isue with my problem ?

Also when i stopped the PHD and start imaging i got very nice photos with exposureup to 3 minutes but when i used PHD it gave me star trails , its the opposite forwhat i expected 😀.

So whats my problem now please? 😊 

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[Bryan]

Did you try to get a good calibration as Brian recommended?  The Guiding Assistant screen shot indicates that you still need to get a good calibration.

You had 3 tries in your first guide log

1.  Failed due to insufficient star movement - Can you move the guide star manually using Tools -> Manual Guide?  Also, you were trying to calibrate at Dec = 90, rather than 20 degrees of zero.  See the Best Practices document.  https://openphdguiding.org/phd2-best-practices/

2.  Failed due to lost star - Again, calibration was at Dec = 90.

3.  Calibration completed, but the two axes are not close to being perpendicular.  Calibration at Dec = 17.5...marginal, but OK.

The calibration pulse is 4500 ms.  This is significantly longer than normal.  This is why the calibration graph moves outside the circle (in 2 steps).   Using your data, I get a value of 900 ms.  How did you determine a value of 4500 ms?

[Brian Valente]

>>>Also when i stopped the PHD and start imaging i got very nice photos with exposureup to 3 minutes but when i used PHD it gave me star trails , its the opposite forwhat i expected

Hi Wael

Your problem is you have a bad calibration, so you are going to have bad guiding. Bad guiding is worse than no guiding, so you are exactly where I expect you to be 😀

You must have a good calibration before Guiding Assistant can be used.

I recommend you follow the steps I previously outlined, that should get you much further along

Brian

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[Ken Self]

Hi Wael

another thing I noticed is that your guiding focal length has been entered as 120mm. This is unusually small as even finder scopes tend to have a focal length of 160mm or more. Can you please describe your guiding setup or provide a picture of it?

The wrong focal length affects the calibration step size calculation amongst other things

Ken

[Wael Omar]

Hello Ken,

My guide scope is Zwo Asi mini guide 30mm and it has focal length 120mm  as described by manfature...also my guide camera is zwo 120mms.

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[Wael Omar]

H Bryan,

I am sorry iam totally new to this and try to figure out evcn the concepts ...you mean by dec 90 is that i am directing to polaris and i should direct my telescope to elestial equator ...right?

Also i attach a ss for my phd recommendation after the calibration.

Sorry again but i am trying to collect the required info to d it right.

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[Ken Self]

Hi Wael

As mentioned before, the Guiding Assistant does not work unless you have a good calibration so you need to concentrate on fixing that first.

The guide log says the HFD for your guide star is 5.39 pixels and you have a pixel scale of 6.45 arcsec/pixel. That means the guide star is nearly 35 arcsec across so your guide scope is almost certainly out of focus.

So start by making sure the guide scope is in focus.

When I analyze your calibration I see a near straight line which shows a drift of more than 12 arcsec per second. That is near enough to sidereal to make me suspect you do not have the mount tracking. 

Make sure your mount tracking is turned on.

Then slew to dec 0 near the meridian and calibrate again. To calibrate, hold the shift key when you click the guide button.

Also, can you tell us what your imaging camera and scope are?

[Bryan]

That is correct...90 degrees Declination is the North Celestial Pole.  The celestial equator Declination is 0 degrees.  The meridian is the line between North and South Poles, i.e. directly overhead.  As a reference point for any location on the Earth, the celestial equator is at an altitude above the horizon equal to 90 degrees minus your latitude.  For example, at the Earth's equator, the celestial equator is 90 - 0 = overhead.

If you have not reviewed it already, please take a look at the PHD2 Best Practices document at https://openphdguiding.org/phd2-best-practices/

Bryan

[Wael Omar]

Hi all,

Its me again , I applied all your advice but the problem still exist, I direct my guide scope to star near the celestial equator and meridian but the calibration fails, I tried to use manual guide of phd but the mount doesn't move at all, it moves very well with directions keys of EQMOD but with PHD no move occurred.

It seems that there is still connection problem with PhD because it always gives me error message that phd couldn't make enough correction, the connection with EQMOD And other apps is ok.

https://openphdguiding.org/logs/dl/PHD2_logs_dSur.zip

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[Wael Omar]

Hello,

I just found something very interesting in my setup, When I started guiding it gave me the usual error that phd can't make enough guiding movements. My setup was to connect camera to pc with USB cable and connect pc to mount by USB cable and use ascom EQMOD.

I thought in adding st4 cable between the camera and mount then everything changed completely... PHD started to guide in the First time , I was so happy that I finally did it.

This is the log:

https://openphdguiding.org/logs/dl/PHD2_logs_CMfh.zip

please could you explain what happened and is this the normal way for connection?

[Bryan]

I wonder if there is a cable connection or even mechanical issue in ONE direction on Dec. A couple pieces of data suggest this.

1.  The Guiding Assistant screenshot shows an enormous Dec backlash in one direction (14+ seconds!) with a reasonable amount in the other direction (565 ms). 14s of backlash renders that mount un-usable.  Was it new or used?  Hopefully, this is a cable issue, not mechanical.

2.  The calibration runs appear to show that the mount never recovers from the moves the PHD makes to calculate guiding parameters.

I suggest using the Manual mount controls under the Tools menu to see if you cam make the mount move in all 4 directions.

It would also be good to wait until others offer an opinion on this hypothesis, before doing anything beyond the above

Bryan

[Bruce Waddington]

Are you 100% certain that you have configured EQMOD according to these settings:

 

https://github.com/OpenPHDGuiding/phd2/wiki/EQASCOM-Settings

 

Are you also certain that you have used the new-profile-wizard to define your equipment setup?  If  you’re unsure, you should create a new one.  Choose between an ASCOM mount connection and an ST-4 connection – don’t try to keep bouncing back and forth between them.  If you can’t get a usable calibration, run the Star-Cross test under the Tools menu.  If you are running with an ASCOM mount connection, disconnect the ST-4 cable between the camera and the mount.   When you finish a calibration, use the Tools/Review Calibration menu item and look at the graph.  If the graph doesn’t show lines that are approximately perpendicular, you can’t proceed.  Make sure the mount is correctly initialized and is tracking at the sidereal rate before trying to do anything with PHD2.  Don’t start fiddling around with PHD2 settings – this isn’t a guiding problem or a PHD2 problem, it’s a problem with your mount or the way you’re operating it.

 

Good luck,

Bruce

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[Wael Omar]

Hi Bryan;

I tried to use the manual guide on PHD but the pc hang up when i do so everytime.

I d like to note that i could use direction keys in EQMOD both RA and DEC without problems.

When i connect the ST4 cable between camera and mount in addition to the usb cable between pc and mount the autoguiding run smoothly and i could took image up to 3 minutes without trails.

Thats why i got confused that how st4 work beside the usb cable to the mount.

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[Wael Omar]

Hi Bruce,

Yes i exactly configure EQMOD  at this setting in the link... i look at it while i was configuring the Eqmod.

I unistalled all drivers and apps and reinstall them again then configure EQmod and PHD again according to PHD Best practise but the problem still exist.... the mount is new not used ....i found that when i connect the st4 cable plus the usb cable to the mount...i got  clean autoguiding  not perfect but still better than using usb alone to the mount . Thats why iam surprised that st4 works beside usb to the mount.

Iam sorry iam in EGYPT and no one here is using EQ mounts at all thats why i have nobody here to look at my problem..i have only you to support me ...thanks for ur help.

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[Chuck Koos]

I've had issues with calibration and guiding also. I've found that ST-4 works, but USB only connection doesn't. I'm still trying to characterize what's going on.

If PHD isn't moving the mount, and then ALL you do is plug in the ST-4 cable, and then it works, your profile is not correct for a USB only connection.

Here is what your profile for an ST-4 and USB connection should look like: (I'm not sure what mount you should have selected for Aux mount.)

Here's what the profile for USB only should look like: (I'm not sure what mount you should have selected for Mount.)

And as Bruce mentioned, if you are using the USB only connection, you MUST disconnect the ST-4 cable.

Another thing I've noticed on my set up that I haven't gotten to the bottom of yet,  is that sometimes the mount tracking (sidereal) gets turned off. The one time I'm sure it happened is when I disconnected the ST-4 cable to go back to a USB only profile. When tracking is off, nothing will work right from my experience. The clue this has happened is if you start the guide camera looping, and the stars march off the screen in time with your exposure. If that happens, go into your hand controller, setup/tracking and select sidereal to get the mount tracking again.

I defer to the experts if they spot any mistakes in what I wrote above, I'm still pretty new to this.

[Wael Omar]

Hi Chuck ,

Thanks alot for your reply....you exactly described what i have faced with guiding.... I repeat everything today and still usb profile not work and also st4 profile not workong...when i connect them both in same time the guiding starts....i cant figure out why this happened....Also you are right , i must turn the tracking on the mount itself but if i turn it on eqmod it doesnt make anything.

My mount is skywatcher eq35.

Today i made polar alignment with sharp cap then i make calibration in phd ...this is the log :

https://openphdguiding.org/logs/dl/PHD2_logs_PQcS.zip

Also this is pic of the graph.

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