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Seanelly

Help with image creep.

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No, I don't mean me or the suspicious character who wanders past your driveway once too often on imaging nights or occasionally shows up at star parties making everyone feel uncomfortable, I mean a problem with my mount, an HEQ-5 PRO that for the past four imaging sessions has progressively become unmanageable.

I noticed on the first night that the 10X view in the DSLR live view of the third star in my alignment routine that I use for positioning and focus using the Bmask continued to drift toward the edge of the screen after my finger was removed from the directional button. It stopped its uncalled for rambling before going off screen and I re-positioned it and went on with my evening.

I was exposing 2 minute images of M3 using PHD2 and lost 2/3 of the subs that night to short star trails,  quite a surprise to me as my polar alignments are now quite accurate, always placing the first alignment star in the field of view, and I've exposed up to 5 minutes some nights with minimal loss, but only connected the dots when on the second night of imaging that darn star tried to run away again by itself. Not knowing what else to do and having already invested the time in setup, I repositioned it and continued my focus routine and then directed the scope to M3.

Once on M3, I framed the DSLR image to roughly match the first night, then turned my attention to activating PHD2, and while it was going through its routine I fired off a few 15s DSLR images to check the framing and noticed that M3 was definitely drifting somewhat toward the top of the screen, but seeing as how it lost its urge to run away and still being acceptably framed, I left it as such and once PHD2 gave me the green I started imaging. I lost 3/4 of the subs that night.

I checked everything I could think of but finding nothing I was worried the third night and sure enough it went exactly as the second, only I lost 4/5 of the subs.

I will say that I have a stubborn streak that prevented me from asking for help until my head became sore from banging it against the wall, I mean, the mount has performed flawlessly for me for six months so maybe I picked up a flaw in my routine or maybe it was just the awkward positioning of the scope imaging M3, the only subject to seemingly engender this creeping problem.

Anyway, the fourth night the image crept so far up the DSLR screen while I was setting up PHD2 that M3 was nearly out of the field of view before stopping, and I lost every sub to short stubbly star trails.

Just to compare, when I first got the scope/mount I was imaging 2 minute subs with no PHD2 and keeping 3/4 or more every time.

I visited my dealer this morning and we spent two hours pouring over it but found nothing, though we were limited in what we could accomplish in-store, so I either have to send it off the California for a month or two (Ahhh!) or hopefully get some idea of how to fix this without voiding warranty.

Please, I leave it in your capable hands for suggestions. Somebody out there surely has seen this problem before.

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Posted (edited)

1) Are you set to sidereal rate? Always worth a check!

2) Is you guide speed set to 0.5x sidereal?

3) How can you be sure that you polar alignment is correct? You could try the routine in PHD or do a quick drift check. This sounds very much like polar misalignment and mounts can easily get a bump. I don't think the star alignment routine is at all a serious test of PA.

Olly

Edit: Do you have a sticking handset button?

Edited by ollypenrice

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Sort of hard to understand what happens. Do you have a video of what the star does?

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What happens to the guide star on the PHD2 screen?  Does this also move or does it stay in place?  

You say you took subs while 'PHD was going through its routine', is this while it's calibrating?  That would produce star trails for sure, and how was the calibration?  Any reported problems?

 

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12 hours ago, ollypenrice said:

1) Are you set to sidereal rate? Always worth a check!

2) Is you guide speed set to 0.5x sidereal?

3) How can you be sure that you polar alignment is correct? You could try the routine in PHD or do a quick drift check. This sounds very much like polar misalignment and mounts can easily get a bump. I don't think the star alignment routine is at all a serious test of PA.

Olly

Edit: Do you have a sticking handset button?

Thanks for responding. all my settings are exactly as they were before this trouble started, and the tech where I purchased the mount verified this.

I'm fairly certain there is nothing amiss in my polar alignment routine because I've been doing it successfully all through the winter and early spring, as mentioned achieving at times 5 minute subs with minimal loss (actually only for M81-M82, but that was 17.5 hours of 5m subs over the course of 6 sessions with no trouble).

I'm not experienced enough to comment on whether the 3-star alignment routine is a serious test of PA, except to say that after my polar alignment I am seeing the first star of the routine close to the centre of the field of view every time now and considered that a good indication that polar alignment is at least close. As to bumping the mount, no way would that happen without it being the first thing I would think of, besides, I'm talking about four straight sessions with the problem getting more serious each time.

As for trying the routine in PHD2 or a quick drift check, these are things I have never attempted nor understand how to do.

I never thought of the sticky button possibility but the tech never mentioned anything and my own test after reading your comments have proved negative.

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5 hours ago, cotak said:

Sort of hard to understand what happens. Do you have a video of what the star does?

I suppose I could try to video with the DSLR. My earlier long-winded explanation was an effort to encompass everything I could think of to help with solutions but I may have simply muddied the waters.

In a nutshell, there seems to be a voltage leak (though the tech where I purchased it said impossible, and I don't know) to one or both of the mount drives that is keeping the mount moving after the handset button is released. It was short-lived for the first couple of sessions, moving the mount only fractionally, but the last session saw the mount continue to move until M3 was halfway across the DSLR field of view! And I'm assuming that somehow the 'leakage', for lack of a better word, continues while imaging, somehow leading to short star trails. 

It will be several days before clear weather will allow me to run any tests, but I put all this out here now so I can possibly have some ideas about what to try to get ahold of the problem. 

If I can get some proof of what is happening, I can get the tech to order the driver(?) board or whatever is needed without having to to ship the mount off to California for God knows how long.

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3 hours ago, almcl said:

What happens to the guide star on the PHD2 screen?  Does this also move or does it stay in place?  

You say you took subs while 'PHD was going through its routine', is this while it's calibrating?  That would produce star trails for sure, and how was the calibration?  Any reported problems?

 

It looks to me like PHD2 is trying to respond to whatever is happening, from what I can tell in the graph, but my guiding has never been great from the start, always fluctuating considerably but never outrageously, which has made it difficult to tell if it is now worse, though if pressed I would say it is worse. The few short subs I took were only for framing the object while PHD2 was going though its routine before giving me the green go-ahead.

I have gone though the Guide Assistant and done everything asked of me and there are no warnings or indications of trouble, and up to this point have really had no problems guiding, achieving 17 hours of 5 minute subs recently for M81-M82 with minimal loss of subs.

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35 minutes ago, Seanelly said:

I suppose I could try to video with the DSLR. My earlier long-winded explanation was an effort to encompass everything I could think of to help with solutions but I may have simply muddied the waters.

In a nutshell, there seems to be a voltage leak (though the tech where I purchased it said impossible, and I don't know) to one or both of the mount drives that is keeping the mount moving after the handset button is released. It was short-lived for the first couple of sessions, moving the mount only fractionally, but the last session saw the mount continue to move until M3 was halfway across the DSLR field of view! And I'm assuming that somehow the 'leakage', for lack of a better word, continues while imaging, somehow leading to short star trails. 

It will be several days before clear weather will allow me to run any tests, but I put all this out here now so I can possibly have some ideas about what to try to get ahold of the problem. 

If I can get some proof of what is happening, I can get the tech to order the driver(?) board or whatever is needed without having to to ship the mount off to California for God knows how long.

Voltage leaks seems bit of a fuzzy term but I suppose its technically possible, if we are taking servo motors. We are talking stepper motors here I think? So in that case you need a operating motor controller being given the wrong signal. Are they controlled in the input end by a voltage? Find that hard to believe as that's an unreliable way to drive a motor controller..

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What figure does Guiding Assistant give for your Polar Alignment error ?

If drifting up the screen is in Dec in your setup  then this is possibly a sign of poor PA.

Michael 

 

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1 hour ago, michael8554 said:

What figure does Guiding Assistant give for your Polar Alignment error ?

If drifting up the screen is in Dec in your setup  then this is possibly a sign of poor PA.

Michael 

 

Any figures requested would have to wait a few days until the weather permitted another imaging setup, but I can't believe that after five months of getting my polar alignment accurate enough for 17 hours of 5-minute subs on M81-82 only a month ago with no trouble, I've suddenly lost my touch. What I am witnessing first off is continued movement of the mount after I release the directional button severe enough now for the object in view to nearly leave the DSLR field of view, and secondly, all my subs at only two minutes exposure now showing star trails severe enough to ruin every exposure. There is something wrong with the mount, and I need proof in some substantial form for my tech to send to SkyWatcher so they can send whatever board or such that I need, otherwise the mount itself must be shipped to California (I'm in Ottawa, Ontario) for analysis for who knows how long.

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41 minutes ago, Seanelly said:

Any figures requested would have to wait a few days until the weather permitted another imaging setup, but I can't believe that after five months of getting my polar alignment accurate enough for 17 hours of 5-minute subs on M81-82 only a month ago with no trouble, I've suddenly lost my touch. What I am witnessing first off is continued movement of the mount after I release the directional button severe enough now for the object in view to nearly leave the DSLR field of view, and secondly, all my subs at only two minutes exposure now showing star trails severe enough to ruin every exposure. There is something wrong with the mount, and I need proof in some substantial form for my tech to send to SkyWatcher so they can send whatever board or such that I need, otherwise the mount itself must be shipped to California (I'm in Ottawa, Ontario) for analysis for who knows how long.

Well sounds like you need to video the behavior, and maybe provide guide logs to back things up. 

Have you tried contacting Skywatcher directly yourself. I have read they are quite responsive.

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34 minutes ago, Seanelly said:

Any figures requested would have to wait a few days until the weather permitted another imaging setup, but I can't believe that after five months of getting my polar alignment accurate enough for 17 hours of 5-minute subs on M81-82 only a month ago with no trouble, I've suddenly lost my touch. What I am witnessing first off is continued movement of the mount after I release the directional button severe enough now for the object in view to nearly leave the DSLR field of view, and secondly, all my subs at only two minutes exposure now showing star trails severe enough to ruin every exposure. There is something wrong with the mount, and I need proof in some substantial form for my tech to send to SkyWatcher so they can send whatever board or such that I need, otherwise the mount itself must be shipped to California (I'm in Ottawa, Ontario) for analysis for who knows how long.

I'm with Olly, it's most likely PA is out, a DARV will prove it in about 2minutes.

M81/82 is closer to the pole DEC 70, you moved to M3 DEC 28, which is much further from the pole, hence more drift.
Have you actually tried PA with the polarscope?
 

 

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As an additional point that has not yet been discussed......

I too have an HEQ5 PRO, used now just for daytime solar but originally was my mobile setup.

The description of mount continuing to move / creep for a few seconds after the drive button is released is one that I experienced with my mount after the first few months of use and was just due to backlash in the worms, more in Dec than in Ra, but present in both, and was completely cured by carrying out the worm mesh adjustment as described in the manual at that time.

I remember that this “creep” after the drive button is released was most noticeable with a three star alignment as the mount balance point tended to swing for the final star of the three star alignment and the mount would continue to move on under gravity and mass momentum for a short distance after the drive button was released.

From your description of the problem so far it seems you are most likely seeing the normal “running in” of a new mount with softening and redistribution of the worm gear grease and bedding together of the various components, plus the general movement and disturbance to the drives caused by normal setup and tear down for each session.

Before sending the mount back I would at least take the motor covers off, check and adjust if necessary the transfer gear mesh tolerances and adjust the worm-gear mesh pressure, this after all, is something that is a normal part of the standard HEQ5 PRO routine maintenance protocol, and used to be documented in the manual, at least the worm-gear adjustment was.

The drive motors on the HEQ5 PRO are stepper motors so they can not “creep” with a direct “leakage” voltage applied, they can only rotate when “pulsed” and if one of the buttons were sticking, or the electronics failed and constantly sending drive signals, you would continue to hear the pulses after the drive button was released.

If you are seeing continual un-commanded creeping, so that the object will slowly drift out of the frame and never stop and you are sure that polar alignment is good then the last thing to check, or perhaps the first thing to check is, does the mount “creep” with the ST4 guide cable disconnected? It is not unusual for the rather fragile ST4 cables to go faulty, or for a guide camera to fail in such a way that it is continually, or intermittently, sending guide corrections to the mount when not commanded to do so, if you are using “on-camera” relays and the mount’s ST4 port for guiding (rather than EQMOD/pulse guiding) then disconnect the ST4 cable at the mount and check to see if the mount continues to “creep” during star alignment and after slewing, if not then check the ST4 cable for damage and the guide camera for malfunction.

HTH.

William.

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Sean

If you can post a the guide log from the affected session (PHD2 stores these automatically and the default location is My Documents) it should be possible to see which axis is causing the problem, whether guide pulses are being sent and not responded to and how good the PA and calibration were.  This could help show if it's a mount problem or something else.

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With the covers off, is it possible to disconnect the drive cable to the dec motor ?

Then repeat your previous test that showed drift.

With the ST4 cable off too.

Michael 

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Sorry for the delay in getting back to everyone kind enough to spare the time with this. For the past two nights I've had the scope set up outside with me dancing and praying for a break in the clouds long enough to get PA and try to get more on top of this, but all I achieved was a couple of rain showers. If we get into drought conditions here in eastern Ontario again this summer at least I'll know what to do.

On 12/05/2019 at 22:09, cotak said:

Well sounds like you need to video the behavior, and maybe provide guide logs to back things up. 

Have you tried contacting Skywatcher directly yourself. I have read they are quite responsive.

Thank you for your input. Video is on my list if it comes to it. I am providing the guide logs for the past 8 sessions (at least I think they are the guide logs you refer to) so a comparison may be made between the before and after. It was during the latest four the problem arose and got progressively worse.

Direct contact with SkyWatcher is something I definitely would be open to. I want at least a couple of clear nights (it looks 50/50 for the weekend) before then to try the suggestions provided and then have more info to provide them if it comes to it.

PHD2_GuideLog_2019-04-28_211801.txtPHD2_GuideLog_2019-04-21_221122.txtPHD2_GuideLog_2019-04-10_235837.txtPHD2_GuideLog_2019-04-06_203111.txtPHD2_GuideLog_2019-05-08_212516.txtPHD2_GuideLog_2019-05-07_212914.txtPHD2_GuideLog_2019-05-05_211227.txtPHD2_GuideLog_2019-05-04_214027.txt

 

On 12/05/2019 at 22:13, wxsatuser said:

I'm with Olly, it's most likely PA is out, a DARV will prove it in about 2minutes.

M81/82 is closer to the pole DEC 70, you moved to M3 DEC 28, which is much further from the pole, hence more drift.
Have you actually tried PA with the polarscope?
 

 

I appreciate your time on this, and to answer your PA speculations, I do use the polarscope in the mount (it has been checked a few days ago by my tech and found to be centered) along with the handset (also checked out for settings) coordinates and the GPS option, and I've learned to supply myself with accurate PA (on a designated level concrete triangle pointing north, to take a little of the guesswork out of it) shortly after acquiring the scope/mount in Nov last year, so say my subs, at least, until recently. I don't say it is definitely not my PA,  as I don't have a lot of experience in imaging, but once I got my PA down it was never an issue until now.

What the heck is a DARV, haha?

 

On 13/05/2019 at 02:55, Oddsocks said:

 

From your description of the problem so far it seems you are most likely seeing the normal “running in” of a new mount with softening and redistribution of the worm gear grease and bedding together of the various components, plus the general movement and disturbance to the drives caused by normal setup and tear down for each session.

Before sending the mount back I would at least take the motor covers off, check and adjust if necessary the transfer gear mesh tolerances and adjust the worm-gear mesh pressure, this after all, is something that is a normal part of the standard HEQ5 PRO routine maintenance protocol, and used to be documented in the manual, at least the worm-gear adjustment was.

The drive motors on the HEQ5 PRO are stepper motors so they can not “creep” with a direct “leakage” voltage applied, they can only rotate when “pulsed” and if one of the buttons were sticking, or the electronics failed and constantly sending drive signals, you would continue to hear the pulses after the drive button was released.

If you are seeing continual un-commanded creeping, so that the object will slowly drift out of the frame and never stop and you are sure that polar alignment is good then the last thing to check, or perhaps the first thing to check is, does the mount “creep” with the ST4 guide cable disconnected? It is not unusual for the rather fragile ST4 cables to go faulty, or for a guide camera to fail in such a way that it is continually, or intermittently, sending guide corrections to the mount when not commanded to do so, if you are using “on-camera” relays and the mount’s ST4 port for guiding (rather than EQMOD/pulse guiding) then disconnect the ST4 cable at the mount and check to see if the mount continues to “creep” during star alignment and after slewing, if not then check the ST4 cable for damage and the guide camera for malfunction.

HTH.

William.

Thank you for that thoughtful reply. Yes, I first noticed the creep on the last star of the three star alignment session in question but this creep is well beyond any settling in of the gears, etc. Once the last star is slewed to, I roughly center it and then exchange the eyepiece/diagonal for the DSLR, then with the handset slew the star to the 10x box on the DSLR live-view screen for focusing with the Bmask. After releasing the directional button, the image continues, slowly, to move in that direction, the first time not very far (we are seeing it at 10x here), but progressively worse each imaging session since, ruining (I'm assuming, somehow someway) more and more subs until the last session saw the object (M3) in unmagnified live-view drift halfway across the field of view while I was busy starting up PHD2! That happened on the last of four imaging sessions that saw things go from bad to worse.

The mount is still under warranty and in fact I have a scheduled appointment in two weeks originally made unrelated to this to have it tweaked, etc., if necessary, as per your routine maintenance comment. But I did bring the mount in last weekend to have it looked at related to this, and two hours later he could find nothing out of the ordinary. He did mention what you've said about the stepper motors and voltage 'creep', etc.

I am definitely seeing uncommanded creepage(?) and I'm almost positive my PA is good, though I must say I only have half a dozen images with very little sub loss to back that up, but I'm confident about it. I have a level concrete triangular pad to aid me in set up and have the polar routine down pat with the polar scope, handset and GPS.

Your suggestions about the ST4, guide cable, etc., have been noted, but I'm still waiting for a break in the weather to test the mount further. The weekend looks like a combination of cloud and clear, so hopefully I'll get some time at it.

The suspense is killing me.

 

On 13/05/2019 at 03:01, almcl said:

Sean

If you can post a the guide log from the affected session (PHD2 stores these automatically and the default location is My Documents) it should be possible to see which axis is causing the problem, whether guide pulses are being sent and not responded to and how good the PA and calibration were.  This could help show if it's a mount problem or something else.

Thanks for taking an interest in my situation. The guide logs (I think!) are posted above with cotak, the latest four the ones where the problem might show and a few previous sessions thrown in for comparison, the before and after. I don't know how to read the logs but if you know of a tutorial could you post a link?

 

 

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Hi Sean

Looked at 4 of your PHD2 logs, but I don't see any Guiding Assistant runs ?

So no indication of the mount's behaviour when guiding is not running - so no PA, Backlash, or PE readings, so also no recommendations from PHD2 as to what settings to use for each night's Seeing conditions.

But as you say your guiding looks okay, apart from some occasional large Dec excursions that overshoot on correction and take a while to settle - a sign of Dec Backlash.

And most puzzling, some of the logs are showing the mount's RA and Dec position, some aren't.

If PHD2 doesn't have that info then you must Calibrate close to where you're imaging, as guiding varies with Dec.

 

Does your mount have Backlash Compensation ON - this attempts to take up the slack on GoTo's, so on manual moves can move the mount after you release the button ?

This would be my guess as to the cause of the problem, not a guiding issue.

 

PHD2 recommends to turn off Backlash Comp on the mount and use the PHD2 Backlash Comp, as calculated by the Guiding Assistant run !!

Finally you are on an old release of PHD2, but I wouldn't change that until your current problems are sorted.

Michael

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Posted (edited)
22 hours ago, Seanelly said:

 

Thanks for taking an interest in my situation. The guide logs (I think!) are posted above with cotak, the latest four the ones where the problem might show and a few previous sessions thrown in for comparison, the before and after. I don't know how to read the logs but if you know of a tutorial could you post a link?

 

 

To interpret the guide logs there is a tool (written by one of the programmers of PHD2) here http://adgsoftware.com/phd2utils I find it very useful for analysing guiding performance.  Among other things it reports that your Polar alignment error was less than 1' :

PAE.jpg.99f671f44d353034e8592702dd49ae1f.jpg

There is a brief explanation of its use on  that page, but if you want to dig a bit deeper, there's a pdf that can be downloaded here https://openphdguiding.org/tutorial-analyzing-phd2-guiding-results/

Looking at the 4 logs for May, I can't see any reason for the target to drift off the screen.  PHD2 is making corrections, albeit of some fairly large excursions, and the guide star is coming back to position, at least as far as the guide camera is concerned. Sample of this below:

corrections.jpg.770ea0c06a7c5cb9357f583527183144.jpg

That suggests that the issue may be flexure between the guide scope and the imaging scope, it doesn't take much movement at all to produce this effect and plastic tipped guidescope ring mounting screws are famous for producing this result, if you have those?

That isn't to say that resolving flexure (if that's what the cause is) will completely resolve star trails, the scatter plot suggests there may some more issues to check:

1889422250_scatterplot.jpg.ce8d0c8fdb8ae648edd6e02af0760e51.jpg

I'll disagree slightly with Michael here, updating to the latest version of PHD2 may improve matters slightly, with better guiding assistant analysis and improved calibration algorithms.  

Finally it may be worth posting guide and debug logs over on the PHD2 Google group https://groups.google.com/forum/#!forum/open-phd-guiding Andy and Bruce are pretty quick to respond and will have much greater insight.

Edited by almcl

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Nice report almcl.

I haven't spotted the statistics/drift box before in Log Viewer, I see it reports PA.

Now you've suggested flexture, I see Sean has an Orion Deluxe Mini Guidescope, which has an absolutely awful finderscope type mount.

Michael

 

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4 hours ago, michael8554 said:

Now you've suggested flexture, I see Sean has an Orion Deluxe Mini Guidescope, which has an absolutely awful finderscope type mount.

Michael

Ah, yes good point.  That could certainly be contributing to the problem, couldn't it?

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19 hours ago, michael8554 said:

...don't see any Guiding Assistant runs ?

But as you say your guiding looks okay, apart from some occasional large Dec excursions that overshoot on correction and take a while to settle - a sign of Dec Backlash.

If PHD2 doesn't have that info then you must Calibrate close to where you're imaging, as guiding varies with Dec.

 

Does your mount have Backlash Compensation ON - this attempts to take up the slack on GoTo's, so on manual moves can move the mount after you release the button ?

This would be my guess as to the cause of the problem, not a guiding issue.

 

PHD2 recommends to turn off Backlash Comp on the mount and use the PHD2 Backlash Comp, as calculated by the Guiding Assistant run !!

Finally you are on an old release of PHD2, but I wouldn't change that until your current problems are sorted.

Michael

Hi, thanks for the help. As to Guiding Assistant, are you saying that I need to activate it before every imaging session, or at least occasionally, because I certainly have not, using it only once to get the whole PHD2 phase of my learning curve off the ground, so to speak, and it seems to have worked out fine until this problem arose.

As to Dec backlash, when I talked to the tech where the mount was purchased about the problem in question he mentioned a belt mod that would improve guiding irrespective of whatever is happening at this particular time, and I presume this would help eliminate some of this?

Backlash comp can be activated through PHD2? In general does the newer release of PHD2 provide benefits?

 

 

17 hours ago, almcl said:

 

There is a brief explanation of its use on  that page, but if you want to dig a bit deeper, there's a pdf that can be downloaded here https://openphdguiding.org/tutorial-analyzing-phd2-guiding-results/

Looking at the 4 logs for May, I can't see any reason for the target to drift off the screen.  PHD2 is making corrections, albeit of some fairly large excursions, and the guide star is coming back to position, at least as far as the guide camera is concerned.

That suggests that the issue may be flexure between the guide scope and the imaging scope, it doesn't take much movement at all to produce this effect and plastic tipped guidescope ring mounting screws are famous for producing this result, if you have those?

That isn't to say that resolving flexure (if that's what the cause is) will completely resolve star trails, the scatter plot suggests there may some more issues to check:

1889422250_scatterplot.jpg.ce8d0c8fdb8ae648edd6e02af0760e51.jpg

I'll disagree slightly with Michael here, updating to the latest version of PHD2 may improve matters slightly, with better guiding assistant analysis and improved calibration algorithms.  

Finally it may be worth posting guide and debug logs over on the PHD2 Google group https://groups.google.com/forum/#!forum/open-phd-guiding Andy and Bruce are pretty quick to respond and will have much greater insight.

Thank you for the link on PHD2 analysis.

And so I believe I can say my PA can be eliminated as the culpit.

I'll also venture to say that flexure between the guide and main scopes is unlikely to show such a drastic change from one session to the other? The Orion guidescope has a pot metal steel bracket that is held securely by the steel mount on the telescope casing and in turn holds the steel tube of the finderscope with steel adjusting screws. While I can't vouch for the performance of it in the wider scheme of things, I can at least say that it did the job just fine throughout a miserable Canadian winter and into spring until the problem in question reared it's ugly head.

I see here that you believe the latest version of PHD2 would benefit, even if only slightly, my guiding, and I will update when this I get this figured out.

The more help the better, thanks for the Google group link.

 

42 minutes ago, almcl said:

Ah, yes good point.  That could certainly be contributing to the problem, couldn't it?

See above for my rebuttal on the scope flexure situation.

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On 15/05/2019 at 04:59, Seanelly said:

I am definitely seeing uncommanded creepage(?) and I'm almost positive my PA is good, though I must say I only have half a dozen images with very little sub loss to back that up, but I'm confident about it. I have a level concrete triangular pad to aid me in set up and have the polar routine down pat with the polar scope, handset and GPS.

Not sure if this is relevant in your case but my HEQ5 Pro can do the "sticky button" trick under special circumstances, which I narrowed down to this: When the mount is recieving a guide signal via ST-4 and you simultaneously press a slew button this sometimes happen. Never press these buttons when guiding is active. To stop the creeping, stop guiding (or pull out the ST-4 plug) and (if necessary) shortly press the opposite slew button.

Another important thing is correct (un)balance. RA = "east heavy" and DEC = slightly unbalanced (front or back). If you have perfect balance (no bias), creeping may occur.

Ragnar

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5 hours ago, lux eterna said:

Not sure if this is relevant in your case but my HEQ5 Pro can do the "sticky button" trick under special circumstances, which I narrowed down to this: When the mount is recieving a guide signal via ST-4 and you simultaneously press a slew button this sometimes happen. Never press these buttons when guiding is active. To stop the creeping, stop guiding (or pull out the ST-4 plug) and (if necessary) shortly press the opposite slew button.

Another important thing is correct (un)balance. RA = "east heavy" and DEC = slightly unbalanced (front or back). If you have perfect balance (no bias), creeping may occur.

Ragnar

Hi, thanks for the comments. I've never had reason to slew the mount when my guiding is active, as PHD2 would immediately 'lose' the star, I believe. Either way, activating guiding and then the DSLR remote shutter release are the last things I do before leaving the rig to do it's work. I will be making a thorough (I hope) check of the handset Friday night, if the weather holds as it is forecast, my first chance to run a few tests since this problem began ten days ago. As for the balance, I went through that with my tech just in case and he assures me I am not mistaken in my setup. But I will take extra care Friday. Hopefully I will have good news to report.

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To sum up:

Your PA is good, and your guiding is good enough that stars shouldn't be drifting.

I'm having trouble understanding what your problem looks like on images.

Perhaps you could post a before and an after jpeg, same durations, from sessions before and after your problem arose ?

Michael

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5 hours ago, michael8554 said:

To sum up:

Your PA is good, and your guiding is good enough that stars shouldn't be drifting.

I'm having trouble understanding what your problem looks like on images.

Perhaps you could post a before and an after jpeg, same durations, from sessions before and after your problem arose ?

Michael

Thanks, I'm glad to see that you confirm my PA/guiding is not the problem.

As I write this the scope/mount is undergoing it's first imaging session since the problem in question arose about ten days ago, crappy weather hogging the entire interval, and irregardless of the full moon, as it makes no difference for test purposes.  I double-checked all connections, mounts, screws, etc., paid close attention to PA and balance and focus, etc., and used PHD2 Guide Assistant before starting on a selection of shortish exposures. I saw no hint of image creep on the third star, so that was an improvement already. I won't have all the data until tomorrow.

 In a nutshell, for four straight imaging sessions, all on M3 for my first crack at this glob, I was seeing the last stars of the three-star alignments, while I was in the process of centering them in the DSLR 10x live-view screen for focusing, continue moving across the DSLR live-view screen even after I released the directional button, not far the first couple of times, though I lost more than half my subs to short star trails, but by the fourth session M3, after I got my focus and re-centered the image, continued to drift halfway across the unmagnified DSLR live-view screen while I was in the process of getting PHD2 running, and all my subs were lost to short star trails, something I haven't had to deal with since my first days getting things up and running. These four sessions were each set up separately, as I'd been doing successfully leading up to that point.

I'll have more to go on tomorrow, but the suspense is killing me.

 

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