PHD2 problems with guiding

Low HFD usually means either clouds passing by or really poor focus. Have you used an IR filter for the camera? That helps in focusing if the camera is IR capable. Given that you have a 50mm f/3.8 there should be plenty of them stars available. Enable multi-star guiding as well.

My suggestion is to use the Profile wizard in PHD2. If you have gone thru that it prompts you to take a “dark library” as @HR_Maurer suggests.

You are going to want to do this with your scope pointed within say an hour of the meridian and close to “0” declination which should put you in the southern sky somewhere.

Once you do that and get PHD2 guiding for a couple of minutes, I like to then go to the “guiding assistant” and run that for 2 minutes (again follow the prompts) once it goes thru that process then look at possibly changing your settings. If you get thru that process most of the time your guiding will be pretty good with maybe a couple of tweaks here and there depending on how your nights vary.

For the most part PHD2 is fool proof.

Good Luck!

Dale

Hi again,

Thanks for the feedback! I haven't had time to test phd2 again in the last few months, but recently I had clear skies again so I was able to test it.

@Bogdan Borz  I see enough stars in my fov and usually use 2 seconds. Also, the guide scope is really well focused.

When I set up my equipment (as in the first post), I didn't have high hopes that something would be different now.
But to my surprise, the guiding worked as it should. But only for a few seconds.

The calibration went smoothly and seemed to work correctly (every time). But when guiding starts, it loses the star after just a few seconds (as you can see in the attached picture). I don't know why this happens.
Also, before I started guiding, I took a long exposure of 30 seconds (iso 3200) and the stars were as round as possible. But after I started guiding and it didn't work as mentioned above, I did the same exposure again but with very poor results. It looks like the mount either didn't track at all or tracked way too fast. But I could hear the mount move (the typical sounds from the stepper motors when it tracks), so I figured that it should track normally, but this isn't the case.

In this ZIP folder below you can find the PHD2 guide and debug logs from yesterday and the day before (I tested it twice with the same results). In the next post there are also the two images (before and after - 30 sec / iso 3200) that I mentioned before, as well as a picture of the guide graph, where you can see the malfuncition very clearly (sorry that the picture is a bit blurry) - I have to send them in two posts because otherwise the folder would be too big (> 1 MB).

Log files (2).zip

Hopefully someone can help me further or show me a solution approach, because unfortunately I no longer know how to get the guiding right.

Thanks for your advise!
Luke

The image with the star trails clearly shows that the mount is not tracking at that point. The guiding graph shows, that the DEC axis only corrects in one direction, which it usually should not. Just a stupid question: did you already started your mount to track and did you set the tracking rate to siderial? If the tracking rate is different, the things you explained could be a result.

In the image with the guide graph, you can see that the selected guide star is too bright. the histogram of the star has a cut of top and the star is saturated. However, this will have a negative effect on guiding, but it should work in general.

I'm using NINA and sometimes after I slew the mount with a faster speed manually and then trying to guide immediately, the selected star "jumps" out of its tracking box. The mount seems to slew at the fast rate for a short while. In this case, I have to manually select siderial tracking again. But I'm not sure, that this is related to your own problem.

Anyway, in my experience, PHD2 is quite fool proof. If you did run the a polar alignment routine which a lot of software offers today (even PHD2 has its drift alignment) and you calibrated using the assistant, it should work at least somehow. Usually it should work even very good, because that's what I do all the time. I assume, there is some step in the things you do around your guiding missing. Here's what should work (just to have it mentioned):

1.) Focus guide and main camera (main camera mainly to be able to plate solve)
2.) unpark mount
3.) calibrate PHD2 guiding
3.) slew to the target
4.) make sure, you or your software selected siderial tracking rate and tracking is on
5.) select guide star
6.) start guiding
…

Maybe you can list the exact steps you do to find a solution. I barely have to change settings in PHD2 itself. I assume, you set the correct focal length of the guide scope in your profile, as well.

There must be a very simple solution to your problem. Everything else would be very surprising.

CS
Christian

Hi,
thanks for all the Feedback!

@Christian Großmann 
I didn't know that there is anything like a "too bright star", so thanks for the hint.

Here are the requested steps (I don't think I missed something)

• focus guide scope
• polar align with sharpcap (<30")


• start GSS (switched from EQMOD to GSS because with EQMOD my mount always stopped tracking automatically after a few seconds (ca. 5 sec) - with GSS this is no problem anymore)
• start apt (because NINA doesn't detect my Canon camera)
• start stellarium
• start phd2


• unpark mount and slew to a star
• start tracking (siderial tracking rate is correct)
• focus main camera (with 3d printed bahtinov mask)


• calibrate phd2 with the assistant
• choose star
• start guiding

@JIAWEI HU 
Thanks for the help. I'm going to try these tips.



I actually just discovered that there is multi star guiding. So I'm also going to try it to see if this brings any improvement. 
I hope that there will be clear skies soon so I can see if any of these tips solve my problem.

Thanks!
Luke

Lukas Bauer:
Hi again,

Thanks for the feedback! I haven't had time to test phd2 again in the last few months, but recently I had clear skies again so I was able to test it.

@Bogdan Borz  I see enough stars in my fov and usually use 2 seconds. Also, the guide scope is really well focused.

When I set up my equipment (as in the first post), I didn't have high hopes that something would be different now.
But to my surprise, the guiding worked as it should. But only for a few seconds.

The calibration went smoothly and seemed to work correctly (every time). But when guiding starts, it loses the star after just a few seconds (as you can see in the attached picture). I don't know why this happens.
Also, before I started guiding, I took a long exposure of 30 seconds (iso 3200) and the stars were as round as possible. But after I started guiding and it didn't work as mentioned above, I did the same exposure again but with very poor results. It looks like the mount either didn't track at all or tracked way too fast. But I could hear the mount move (the typical sounds from the stepper motors when it tracks), so I figured that it should track normally, but this isn't the case.

In this ZIP folder below you can find the PHD2 guide and debug logs from yesterday and the day before (I tested it twice with the same results). In the next post there are also the two images (before and after - 30 sec / iso 3200) that I mentioned before, as well as a picture of the guide graph, where you can see the malfuncition very clearly (sorry that the picture is a bit blurry) - I have to send them in two posts because otherwise the folder would be too big (> 1 MB).

Log files (2).zip

Hopefully someone can help me further or show me a solution approach, because unfortunately I no longer know how to get the guiding right.

Thanks for your advise!
Luke

Hi Luke,

Well, it is pretty much clear that the mount is simply not guiding when you connect it to PHD. Pretty weird behaviour. Could you please show us some screen captures from your brain settings in PHD2 (Camera, Guiding  and Algorithm)? It is not possible to be able to calibrate and guide with the assistant and then to stop guiding like this. Is the calibration correct? Sometimes the problem is EQMOD that does not communicate well with the mount, try to increase the impulse duration.

Bogdan

Lukas Bauer:
Hi,

@Christian Großmann

I don't think These issues are related, because sometimes the guiding is bad (non-existend) from the beginning, wheras EQMOD always needs a few seconds before stopping. But I'm going to try and just use the to programms and nothing else.


@Bogdan Borz

Always good to hear that I have an issue that is impossible.
Although I don't use EQMOD anymore, I am going to try increasing the impulse duration. 
The calibration should be correct - it works flawlessly every time.

Here are the pictures from the brain settings:

brain settings.zip

Thank you for your help!
Luke

Hi Luke,

: ). The problem you have is real, what I said that is impossible for the mount to track correctly on its own, for PHD2 to calibrate and be able to move the mount for the correct distance during calibration and then to stop tracking during guiding.

It seems that you entered a wrong number for the camera pixel size 24 (probably 2.4) and the search area is 15. If that's the case, it will never work. Try with the correct pixel size and search area 50 let's say, like this it won't lose the star quickly. Still puzzles me how can it calibrate correctly. 

Bogdan

Well, you have 0 gain. That's wrong. Set it at 90%, if not you won't be seeing any stars if the field contains only faint stars. You have no noise reduction. Try any, median for example. 

You calibration step is not the same as mine for your setting, but I don't know what are your advanced settings (the button next to the step size) in Guiding. 

I forgot to ask you about your guiding speed (compared to sidearal) how much is it? I use 0.8 for example. My settings give me a step of 1050 ms for a 25 pixel calibration distance. 12 steps.

So check the advanced parameters too, but try to modify the camera settings first.

Bogdan

Try it at 0.8 for example, lower than the sidereal speed (the speed of the sky). If you make corrections faster than the sky movement, it will be hard to reach equilibrium.

Second, your declination is not 0. Don't tell me you live at the Equator   : ). Put the dec where you image from, if not, it's a false data location for your calibration.  Vitis Austria is 48°. So put this in the setting.

Let’s try all these modifications. I think it will work. Usually I lower the aggressiveness, but you have to check when is guiding.

Hi, 
after a while, yesterday evening the clouds finally started to go away and I could test the guiding. 
It is definitely better than before, but I noticed a very strong drift in the Ra axis:

guide log Ra-Drift.zip

Does this mean, that my tracking rate is too small or too big?

Another thing that I noticed, was that the automatic star choice is always extremely bad and results in PHD2 constantly losing the star. Even if I pick the star manually, it is there in one exposure but not in the next one. Therefore PHD2 loses the start again. Sometimes I even see next to no stars with already 3 sec exposure time. I also tried putting the gain at 95 and 100, but nothing really helped. 
The picture which is linked above was a rare moment, where PHD2 locked on a star and didn't lose it. Therefore I was able to record that error.

This is the guide log from yesterday evening (Debug log is too big, so there is only the guide log - should I post the Debug log too?)

log files new (3).zip

Thanks for the help!
Luke

Hi, as far as I know the gain is currently set to 100.
I don't know why PHD2 didn't correct anything, I just though that it just wouldn't show. 
The mount did respons to the PHD2 signals.
Thanks!