Disappointed with guiding Mesu - logs now attached

[gorann]

On 01/04/2020 at 17:33, Laurin Dave said:

Interesting Goran...  do you run the same guide cam exposure times on both mounts...    I also sometimes get a light leak from the OAG along the stalk..  all those LEDs I expect even though most taped over 

Yes, I think they are both on 3 seconds, but when I have been playing around with it (from 1.5 to 5 s) it does not seem to make much of a difference. And thanks, I will now try to seal off any possibilities of light leakage!

[Skipper Billy]

15 minutes ago, gorann said:

Yes, I think they are both on 3 seconds, but when I have been playing around with it (from 1.5 to 5 s) it does not seem to make much of a difference. And thanks, I will now try to seal off any possibilities of light leakage!

If changing the exp time doesnt make much difference then it would suggest that its not a seeing related problem ?? 

[gorann]

2 minutes ago, Skipper Billy said:

If changing the exp time doesnt make much difference then it would suggest that its not a seeing related problem ?? 

Maybe you misunderstood my comment - I do not think I have a problem with guiding (but maybe with light leaking into one of my OAGs). I think my guiding on both mounts are just as good as seeing allows (so the mounts do their jobs quite well) so that is why changing exposure times makes no difference.

[Skipper Billy]

Ah - I see.

David.

[tooth_dr]

Hi guys

PHD2 logs attached from last night.  I did a bit of faffing about earlier on, plus it failed on calibration twice with the OAG.  I redid my PA with SharpCap to 'excellent' accuracy.  And then I went over to my finderscope.    Pretty poor results, unusable data from the 10" scope.  Any suggestions welcomed!  I believe I have the mount really well balanced in all dimensions, even adding just the dust cap to the 10" causes it to move, so the mount has very free movement with clutches and locks off.

Help!

 

 

 

PHD2_DebugLog_2020-04-06_214107.txt PHD2_GuideLog_2020-04-06_214107.txt

[tooth_dr]

Quick stack of lights 25 x 600s from last night

 

[tooth_dr]

If anyone can recommend anything to do that would be great.  I've attached my settings below.  One observation - on the 5th screen shot below, the PHD2 equipment profile box doesnt say the same name as the profile I was using.  I had a different camera and/or finderscope.  This may not matter as I already had PHD2 open ie SGPro didnt open it.  Is this just for when PHD2 isnt open and it opens and selects the profile.  The same error also applies to the control box settings also in SGPro.

The weather is looking possibly ok for next week, so if there is anything wrong please let me know.  Also when I do the setting up on PHD2 it automatically detemines my mounts guide speed at 0.33.  Is this correct and where is this parameter stored?

 

Thanks in advance.

Adam.

 

[almcl]

Don't have experience of Mesu mounts, but looking at your guide log, the periodic error looks larger than I would have expected.  Maybe my expectations are wrong but the 5 hours session looks like this with the corrections removed:

It guides out beautifully, and the seeing (as shown by the DEC trace below) looks pretty poor, so maybe the conditions (and 3 second guide exposure) are more to blame than the mount:

 

[Laurin Dave]

Pretty sure SGPro will tell PHD to use the profile that is set in the Equipment Profile or Control panel ( so long as the guide camera and mount are the same )..  so if it’s using 225mm focal length with the OAG the calibration movements will be so far from what it expects that it fails .  Could also explain why the PE appears to be 4 times bigger (ratio of focal lengths) than it should be ..

Dave

[tooth_dr]

1 hour ago, Laurin Dave said:

Pretty sure SGPro will tell PHD to use the profile that is set in the Equipment Profile or Control panel ( so long as the guide camera and mount are the same )..  so if it’s using 225mm focal length with the OAG the calibration movements will be so far from what it expects that it fails .  Could also explain why the PE appears to be 4 times bigger (ratio of focal lengths) than it should be ..

Dave

Thanks Dave.

Just to further clarify - I originally used a SW 185mm finder to guide epsilon on the Mesu with a 120MM. When I changed over the epsilon to the 10” I just left the SW finder attached to the epsilon as it was bolted directly.

I thought I’d give an OAG a go, with a 178MC I had sitting doing nothing.  I bought an OAG but that didn’t give great results - due I think to a loose stalk - now rectified.

Last year I got an Altair Astro guide scope as part of other used stuff I bought, and given the limitless loss capacity I thought it would be better than a SW finder scope. I used it with my 120mm.  It has a longer focal length at 225mm than the SW one so I figured it would give me a better “/px ratio for guiding the 10” 1200mm focal length.

Last night that guide log is from the Altair 225mm scope and the 120mm.  So not that much different from what SGPro thought with the SW guider at 185mm and 120mm.  I was not using the OAG last night.

I manually checked my calibration steps last night using PHD2, when it failed, but got a variety of figures. I think it depends on Dec too  

Im sure this is a software configuration issue or user error here 🤦🏼

 

Edited April 7, 2020 by tooth_dr

[tooth_dr]

2 hours ago, almcl said:

Don't have experience of Mesu mounts, but looking at your guide log, the periodic error looks larger than I would have expected.  Maybe my expectations are wrong but the 5 hours session looks like this with the corrections removed:

It guides out beautifully, and the seeing (as shown by the DEC trace below) looks pretty poor, so maybe the conditions (and 3 second guide exposure) are more to blame than the mount:

 

Thanks so much for this analysis. If the correct details are in PHD2, then I agree that PE is well in excess of what I expect.

Do you think longer or shorter guide exposures based on the seeing?

Thanks again

Adam 

[almcl]

Strong non-expert disclaimer but I *think* shorter might be worth a shot. Not sure if this would mitigate all the seeing fluctuations, but worth a try. 

Do you have separate 'New equipment' profiles for OAG and guidescope binned and unbinned?  (4 profiles in all.)

[tooth_dr]

57 minutes ago, almcl said:

Strong non-expert disclaimer but I *think* shorter might be worth a shot. Not sure if this would mitigate all the seeing fluctuations, but worth a try. 

Do you have separate 'New equipment' profiles for OAG and guidescope binned and unbinned?  (4 profiles in all.)

Thanks again.  I do have separate profiles on PHD2.  Ive heard of people using longer to avoid seeing fluctuations so that was my reasoning. 

[Skipper Billy]

When I am imaging close to the horizon and/or in poor seeing conditions I get up to 7 sec exposure on my guide cam. In good conditions I usually run 3 sec.

 

[Laurin Dave]

Hi Adam

I'd suggest longer is better as short exposures will chase the seeing..  Had a look at your settings and can't see anything obviously wrong although it is these I would suspect ..  also a quick look at your logs  ..  the calibration steps at 1200 mm look to me as if the guide camera (or something else) may still be a bit wobbly (on the basis that my OAG at 1070mm returns calibration points on a straight line) ... and on some of the graphs the corrections on Dec are in the wrong direction..   Some suggestions for fault finding  .. take SGPro out of the equation to isolate that as a cause ...   guide via ST4 (ie On Camera) ..    also try the guiding assistant for a couple of PE cycles (ie 10-20 mins) through the 225mm without SGPro  - this should give you the PE..  and as an experiment/ test just attach a guide camera to your reflector (ie in place of the imaging camera) and see if that works... (will rule out wobbly OAG)

HTH

Dave

[david_taurus83]

Another daft suggestion from me Adam! Is this a recent issue? Are all the times correct in all the various software as we've not long had DST springing forward?

[tooth_dr]

@Laurin Dave @david_taurus83

Ive attached a guidelog from before DST, and from before I changed over my scope to the 10".  Would you have look at guiding trace #3 which is 2 hours and 31 minutes long please.

~Screen shots~ whats going on with the PE in the second one?

 

 

PHD2_DebugLog_2020-03-15_194511.txt PHD2_GuideLog_2020-03-15_194511.txt

[Laurin Dave]

Adam

Looks like that's to do with the "failure to settle" report and some sort of re-setting .. its showing a general drift owing to Polar alignment and the PE shows as the small sinusoidal overlay on the downward drift..  

Dave

[steppenwolf]

1 hour ago, Laurin Dave said:

I'd suggest longer is better as short exposures will chase the seeing.. 

I very much agree with this and for my Mesu, 3 seconds seems the best compromise.

[tooth_dr]

I getting a PA using sharpcap of <30” but I haven’t my location set so I’m not accounting for refraction.  When PHD2 measures my PA using GA it says 2m’ or more, so I’m not sure where the inaccuracies lie. I was going to buy a Polemaster camera, but then I read mixed reviews on it too. 

[steppenwolf]

26 minutes ago, tooth_dr said:

I was going to buy a Polemaster camera, but then I read mixed reviews on it too. 

I use one on mine, Adam and find it more than adequate although I am sure that a drift alignment would be more accurate. I’m getting lazy in my old age!

[Laurin Dave]

2 minutes ago, tooth_dr said:

I getting a PA using sharpcap of <30” but I haven’t my location set so I’m not accounting for refraction.  When PHD2 measures my PA using GA it says 2m’ or more, so I’m not sure where the inaccuracies lie. I was going to buy a Polemaster camera, but then I read mixed reviews on it too. 

That's easily good enough not to cause any issues so I wouldn't worry about your PA being the cause of our woes...  also just checking my PHD settings I have hysteresis at 0.3 and min mo's of 0.2... 

[david_taurus83]

I'm not an expert looking at those logs but its guiding with a quarter of a pixel peak to peak so the limiting factor here might be the focal length of that guide scope.

[david_taurus83]

Is there a reason the guide rates are 5" and not 7.5" (0.5 sidereal) like you would expect if using EQMod?

 

Regardless of what the GA recommends, I always try setting the min movements to 0.1 pixel on each axis.

Edited April 8, 2020 by david_taurus83

[tooth_dr]

2 minutes ago, david_taurus83 said:

Is there a reason the guide rates are 5" and not 7.5" (0.5 sidereal) like you would expect if using EQMod?

I’m not sure where to set the guide rates at, or how to adjust it. It says guide rate 0.33 in PHD2 calibration wizard.