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When Push Here Dummy doesn't work in PHD2

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#1 pemongillo

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Posted 21 September 2021 - 04:29 PM

Trying to figure out why my iOptron CEM26, ASIAIR PRO and ZWOASI290 guide camera are having trouble calibrating before guiding can begin. I came across this statement in a tutorial related to troubleshooting PHD guiding. "If you're not plotting, it's a lot easier if you had your guide camera square so that RA and Dec line up with x and y (or y and x). If RA+ moves mainly in x, does RA- move the opposite way in x? Does Dec move in y and not x? It should..." 

 

What do they mean have your guide camera square so that RA and DEC line up?

 

Thanks



#2 rkinnett

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Posted 21 September 2021 - 04:49 PM

Rotate your guide cam such that when you slew in RA or DEC, stars move up, down, left, or right, i.e. horizontally or vertically, as opposed to at some odd angle.  For operability sake, it's useful to figure out which guide cam orientation results in stars moving left/right when you press left/right on the HC, and up/down when you press up/down on the HC.  Axes may be inverted (press up, stars move down), but at that orientation its's still easier to figure out how to adjust things when you need to.  Hope that helps.

 

Edit:  I haven't experienced issues when I didn't make any attempt to align the guide cam.  Try the Guiding Assistant in PHD2 if you haven't already.


Edited by rkinnett, 21 September 2021 - 05:08 PM.

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#3 bobzeq25

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Posted 21 September 2021 - 05:20 PM

Trying to figure out why my iOptron CEM26, ASIAIR PRO and ZWOASI290 guide camera are having trouble calibrating before guiding can begin. I came across this statement in a tutorial related to troubleshooting PHD guiding. "If you're not plotting, it's a lot easier if you had your guide camera square so that RA and Dec line up with x and y (or y and x). If RA+ moves mainly in x, does RA- move the opposite way in x? Does Dec move in y and not x? It should..." 

 

What do they mean have your guide camera square so that RA and DEC line up?

 

Thanks

I can't see why it would matter.  What difference can the orientation of the guide camera sensor possibly make?  You're only using a small area of it.

 

Whose tutorial?  Reference?  You see a lot of strange ideas on the Internet.  One principal.  Don't take advice from anyone unless you can see their images.  That cuts out a _lot_ of ignorant nonsense.

 

I've been imaging successfully for five years (within the limits of my talent <smile> ) and I've never worried about this.  PhD2's calibration routine should be insensitive to this factor.  It moves the calibration star maybe 20 pixels in each direction.  What difference does the orientation of the rest of the sensor make?  It's just sitting there, unused.


Edited by bobzeq25, 21 September 2021 - 05:22 PM.

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#4 pemongillo

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Posted 21 September 2021 - 05:49 PM

I can't see why it would matter.  What difference can the orientation of the guide camera sensor possibly make?  You're only using a small area of it.

 

Whose tutorial?  Reference?  You see a lot of strange ideas on the Internet.  One principal.  Don't take advice from anyone unless you can see their images.  That cuts out a _lot_ of ignorant nonsense.

 

I've been imaging successfully for five years (within the limits of my talent <smile> ) and I've never worried about this.  PhD2's calibration routine should be insensitive to this factor.  It moves the calibration star maybe 20 pixels in each direction.  What difference does the orientation of the rest of the sensor make?  It's just sitting there, unused.

https://www.cloudyni...ere-dummy-r2677



#5 bobzeq25

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Posted 21 September 2021 - 06:38 PM

1.  If I ever disagree with Dr. Stark, ignore me.  <smile>

 

2.  But, I think he's saying if you look at just the numbers in the guide log when calibrating, they're easier to interpret if the RA moves only in the x coordinate, and the DEC moves only in y.  I agree with that.

 

But I never just look at the numbers, I look at the plot seen in Box number 2, which is now available as a menu item ("review calibration data") in PhD2.  Maybe it wasn't in PhD originally? 

 

Can anyone say?

 

In Box number 2 you can see the mounts behavior even though the RA and DEC motions don't fall along the axes, they're at an angle to it.

 

So, I think the important phase is "if you're not plotting". 

 

These days, PhD2 plots the data for you, so you never have to be not plotting.

 

And "If RA+ moves mainly in x, does RA- move the opposite way in x? Does Dec move in y and not x? It should..."  is talking about what happens if the lines are perpendicular.   PhD2 gives you a numerical measure of how perpendicular they are.

 

My bottom line.  I think the wording you're talking about was important in 2012, with PhD, which did not plot the calibration data.  And, in 2021 (or whenever), PhD2 has made it obsolete by plotting the calibration data for you if you click "Review Calibration Data.

 

What do people think?


Edited by bobzeq25, 21 September 2021 - 06:59 PM.

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#6 OldManSky

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Posted 21 September 2021 - 06:39 PM

Bob, he is using the tiny, crippled PHD2 in the ASIAIR. He doesn’t have those options, sadly.


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#7 bobzeq25

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Posted 21 September 2021 - 07:01 PM

Bob, he is using the tiny, crippled PHD2 in the ASIAIR. He doesn’t have those options, sadly.

Thanks.  Just to confirm.  He has no access to "Review Calibration Data"?

 

If so, I think he needs to either plot the data himself (tedious), or adjust the camera so the RA axis moves along the x axis, as explained in "If not plotting...".

 

And then I think this is a dealbreaker for the ASIAir.  I _often_ "Review Calibration Data" if I'm having issues.


Edited by bobzeq25, 21 September 2021 - 07:05 PM.

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#8 pemongillo

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Posted 21 September 2021 - 07:22 PM

Thanks.  Just to confirm.  He has no access to "Review Calibration Data"?

 

If so, I think he needs to either plot the data himself (tedious), or adjust the camera so the RA axis moves along the x axis, as explained in "If not plotting...".

 

And then I think this is a dealbreaker for the ASIAir.  I _often_ "Review Calibration Data" if I'm having issues.

I have complete access to PHD data from my ASIAIR PRO. I posted them in and earlier post looking for help with my calibration. 

 

https://www.cloudyni...-guiding-logs/ 

 

This question came up in my search for an answer. Just for the record OldManSky, your sarcasm is not appreciated.



#9 KTAZ

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Posted 21 September 2021 - 07:34 PM

I have complete access to PHD data from my ASIAIR PRO. I posted them in and earlier post looking for help with my calibration. 

 

https://www.cloudyni...-guiding-logs/ 

 

This question came up in my search for an answer. Just for the record OldManSky, your sarcasm is not appreciated.

Hmmm...I'll take a risk here and say that OMS wasn't really trying to be sarcastic; it's just a fact that the ASIAIR uses a highly truncated version of PHD that does not have all the function of the full version.


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#10 OldManSky

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Posted 21 September 2021 - 07:40 PM

Hmmm...I'll take a risk here and say that OMS wasn't really trying to be sarcastic; it's just a fact that the ASIAIR uses a highly truncated version of PHD that does not have all the function of the full version.

Correct. No sarcasm at all - the software in the ASIAIR does not have the functions Bob mentioned. And many others. You have acces to the log text files after the fact, you don’t have the tools to do in real-time, while you’re setting up and guiding, that the full version of PHD2 has.  The version of the software in the AsiAir, compared to PC versions, is indeed tiny and crippled.


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#11 pemongillo

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Posted 21 September 2021 - 07:53 PM

Correct. No sarcasm at all - the software in the ASIAIR does not have the functions Bob mentioned. And many others. You have acces to the log text files after the fact, you don’t have the tools to do in real-time, while you’re setting up and guiding, that the full version of PHD2 has.  The version of the software in the AsiAir, compared to PC versions, is indeed tiny and crippled.

Sorry, but if  "Bob, he is using the tiny, crippled PHD2 in the ASIAIR" is not true and misplaced sarcasm I don't know what is. I've been at this for less than a year and this site is pretty much void of this. But one minor incident won't keep me away. This site is a wealth of information and it is a place for beginners to get help from old pros. Consider us having shaken hands.



#12 17.5Dob

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Posted 21 September 2021 - 08:04 PM

Guide camera orientation is absolutely NOT required to get calibration. That's part of the calibration process. Are you using a proper step size., did you have PHD calculate it for you ?. What dec are you trying to calibrate at ?


Edited by 17.5Dob, 21 September 2021 - 08:05 PM.

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#13 pemongillo

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Posted 21 September 2021 - 08:22 PM

Guide camera orientation is absolutely NOT required to get calibration. That's part of the calibration process. Are you using a proper step size., did you have PHD calculate it for you ?. What dec are you trying to calibrate at ?

My logs are posted in this link. Don't know how to add files here in responses. 

 

https://www.cloudynights.com/topic/790231-understanding-phd-guiding-logs/


Edited by pemongillo, 21 September 2021 - 08:25 PM.


#14 jonnybravo0311

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Posted 21 September 2021 - 09:39 PM

I don't own the ASIAir, so I am not sure of the limitations of its implementation of PHD2. One thing that may be applicable to you, however, is where your scope is pointing when trying to do the guiding calibration.

 

In the full version of PHD2, you generally want to calibrate while pointed as close to the meridian along the celestial equator as possible. Are you able to configure guiding on the ASIAir Pro independent of the target you wish to image? In other words, if you're going to image something like the Iris Nebula, could you first calibrate your guiding by pointing the scope to the south (assuming you're in the northern hemisphere), then slew back to your intended target and start guiding/imaging?



#15 OldManSky

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Posted 22 September 2021 - 04:42 AM

Sorry, but if  "Bob, he is using the tiny, crippled PHD2 in the ASIAIR" is not true and misplaced sarcasm I don't know what is. I've been at this for less than a year and this site is pretty much void of this. But one minor incident won't keep me away. This site is a wealth of information and it is a place for beginners to get help from old pros. Consider us having shaken hands.

What is true is that the version of PHD that is in the ASIAIR is tiny and crippled compared to the full PC version, and it does not have the functions that Bob was suggesting you try. I’m unclear on why stating that true fact would offend you, and I’ll point out that in the other thread I was the one that showed you the log viewer and helped you understand the calibration graph it showed, so I’m also unclear as to why you would think I wasn’t being helpful. 

 

So so just for future reference, and as a helpful tip to a beginner from an old pro, the PC version of PHD has some really nice and helpful features that, if you indicate you’re having trouble guiding, some people may suggest you use. If you’re using the ASIAIR, you should probably let them know that you can’t use those helpful tools, as they’re not in the version you are using.  Then the old pros can point you to other tools like the log viewer.


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#16 pemongillo

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Posted 22 September 2021 - 07:59 AM

So I think I can conclude this thread with a few things.

1. For some reason I was still not able to calibrate with my ASIAIR last night. Not sure why at this point.

2. I learned enough pretty quickly to use my laptop with PHD2 and it calibrated quickly, guided well and I did some 10 minute exposures with nice sharp round stars.

3. That's a relief, because I was beginning to think something was wrong with my mount.

4. I need to concentrate on figuring out what is not happening between my ASIAIR and my mount regarding guiding.

5. Got a few months to sort it out, before I go off the grid for the winter in Arizona, when my ASIAIR will be indispensable because I will only have battery power and solar charging.

 

Thanks for the help.


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#17 michael8554

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Posted 22 September 2021 - 08:14 AM

Looking at your GuideLog in the other post:

 

As already mentioned, your Dec Calibration is failing.

 

On your last Cal, at around Dec = 0, RA Cal took 7 steps, and the calculated Guide Rate was 6.25arcsec/sec.

 

Dec Cal failed because it was taking over 30 steps to clear Backlash, and then over 40 Cal steps, before giving up.

 

Assuming your mount really doesn't  have that huge Dec Backlash, it points to poor connection to Dec.

 

Or somehow Dec has a very much lower Guide Rate than RA.

 

In diagnosing mount connection problems, the PHD2 "Star Cross" test is useful, and is best carried out with the guidescope aligned to RA, as discussed earlier.

 

Then whichever axis has failed the test is easily identified.

 

But that test is not available in this hacked version of PHD2.

 

Which is why Push Here Dummy isn't working........


Edited by michael8554, 22 September 2021 - 08:15 AM.

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#18 OldManSky

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Posted 22 September 2021 - 08:18 AM

So I think I can conclude this thread with a few things.

1. For some reason I was still not able to calibrate with my ASIAIR last night. Not sure why at this point.

2. I learned enough pretty quickly to use my laptop with PHD2 and it calibrated quickly, guided well and I did some 10 minute exposures with nice sharp round stars.

3. That's a relief, because I was beginning to think something was wrong with my mount.

4. I need to concentrate on figuring out what is not happening between my ASIAIR and my mount regarding guiding.

5. Got a few months to sort it out, before I go off the grid for the winter in Arizona, when my ASIAIR will be indispensable because I will only have battery power and solar charging.

 

Thanks for the help.

Good luck.  A good start might be to write down all the settings you have in the PC version, and make sure those you can set in the ASIAIR version are the same...


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#19 pemongillo

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Posted 22 September 2021 - 10:07 AM

Good luck.  A good start might be to write down all the settings you have in the PC version, and make sure those you can set in the ASIAIR version are the same...

I just finished doing that. I'll figure it out....not very good at letting things go until I figure them out.


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#20 bobzeq25

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Posted 22 September 2021 - 10:13 AM

I have complete access to PHD data from my ASIAIR PRO. I posted them in and earlier post looking for help with my calibration. 

 

https://www.cloudyni...-guiding-logs/ 

 

This question came up in my search for an answer. Just for the record OldManSky, your sarcasm is not appreciated.

The question is.  Do you have access to "Review Calibration Data"?  If so the material you quoted is irrelevant, it does not apply to recent versions of PhD2.  If you do not, that tells you how to make your analysis of your calibration data easier.  Otherwise you'll have to make a plot.

 

And, if the situation is otherwise, I will never get an ASIAir with its tiny crippled version of PhD2.  <smile>  It's missing a critical process for me.  I personally don't use "Star Cross", but I can see how it too could be important.


Edited by bobzeq25, 22 September 2021 - 10:19 AM.

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#21 bobzeq25

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Posted 22 September 2021 - 10:15 AM

I have complete access to PHD data from my ASIAIR PRO.

 But, do you have "Review Calibration Data"?



#22 bobzeq25

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Posted 22 September 2021 - 10:17 AM

I don't own the ASIAir, so I am not sure of the limitations of its implementation of PHD2. One thing that may be applicable to you, however, is where your scope is pointing when trying to do the guiding calibration.

 

In the full version of PHD2, you generally want to calibrate while pointed as close to the meridian along the celestial equator as possible. Are you able to configure guiding on the ASIAir Pro independent of the target you wish to image? In other words, if you're going to image something like the Iris Nebula, could you first calibrate your guiding by pointing the scope to the south (assuming you're in the northern hemisphere), then slew back to your intended target and start guiding/imaging?

That's a tweak.   If he's having big problems it won't be the cause.  There can be good reasons why calibrating elsewhere (and/or turning off "DEC compensation") can be useful.


Edited by bobzeq25, 22 September 2021 - 10:21 AM.

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#23 rgsalinger

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Posted 22 September 2021 - 10:48 AM

Two things I'm wondering.

 

First, what is the DEC guide rate set to in the driver? The PHD log that was downloaded does not tell me what's been set in the mount driver for guide rate. If it's something really small for DEC, that could be why the mount is not moving in DEC. Or you have turned off DEC guiding in some way in the GUI that ZWO has put together. Second, you could somehow have created a situation with enormous DEC backlash. I doubt it but still it's possible. You just need one cable stuck somewhere to get this- it's a long shot, though. 

 

I don't really know why ZWO hacked up PHD rather than simply porting the open source code but that's what they did. So, use a PC and real PHD to eliminate mount problems from the equation would be my first step. Then if real PHD works, it's a question for the wizards who wrote the code for the AP to answer. 

 

Personally when I set up my systems I get the camera axes parallel to the mount axes every time. That makes it easier to see what's going on if there is a problem. I always use ASCOM guiding. I always calibrate that the intersection of the meridian and the celestial equator.  I want to get the best possible calibration numbers. 

 

Rgrds-Ross


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#24 bobzeq25

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Posted 22 September 2021 - 10:58 AM

 

 I always calibrate that the intersection of the meridian and the celestial equator.  I want to get the best possible calibration numbers. 

 

 

If you want the "best possible calibration numbers" you might want to read the guiding discussion in this superb book.  He discusses why it might be useful to vary from standard methods.  As often the case in DSO AP, there are complications.

 

https://www.amazon.c...h/dp/1138055360

 

None of this will solve the OP's problems, which are fundamental.  It's another tweak.


Edited by bobzeq25, 22 September 2021 - 11:01 AM.

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#25 rgsalinger

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Posted 22 September 2021 - 12:01 PM

The arithmetic is quite clear - the most accurate calibration numbers will be obtained by calibrating always at the meridian and the equator and then using DEC compensation.

 

I've read Chris's book and the only thing that I recall is that he seems to think that if you decide to image something at DEC 80 or so, you might want to turn off DEC guiding altogether. I don't recall anything in the book that says it's inherntly better to calibrate at DEC 50 rather than DEC 0.

 

Thinking about it, though, if you were imaging from the Congo, DEC 0 is right on the horizon and that would make me vary my workflow. That's a good edge case! Some people are imaging these days from near the equator. 

 

Rgrds-Ross


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