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Re: Exos-2 PMC-8 - pier extension & axes stabilty

Robert Hoskin <r_hoskin@...>
 

Ok.  I'll send you a note separately - but I'm surprised.  You didn't get helped?




From: "drunkendogg@... [ESPMC-Eight]"
To: ESPMC-Eight@...
Sent: Sunday, June 17, 2018 3:00 PM
Subject: [ESPMC-Eight] Re: Exos-2 PMC-8 - pier extension & axes stabilty

 
Bob - Could you send me the instructions ES sent you to adjust your worm and ring gears?



Re: Exos-2 PMC-8 - pier extension & axes stabilty

Jennifer Shelly
 

Bob - Could you send me the instructions ES sent you to adjust your worm and ring gears?


Re: Newbi in need of help.

Jeny@
 

I do some backyard visual observations with my pmc-8/150 Mak setup and seems that goto work fine with just polar alignment.
Targets got put in eyepiece fov and needs just slight adjustment to put em in the middle.


On Tuesday, June 5, 2018, 6:23:39 PM EDT, chris_moses@... [ESPMC-Eight] wrote:


 

Hi,

   Welcome to the group.
    For polar aligning, don't forget to do a basic level.  No need to get it exact, but it makes adjusting the ra and dec easier as they will move the mount at 90-degree angles.


Re: ASCOMPAD and PMC-8 Connection Problems

hubbell_jerry@...
 

Hi Mark,

Good to hear you had positive results with your auto-guiding even with the deteriorating conditions. You should calibrate the guide system near where your target is for best results. You definitely DO NOT want to calibrate near the horizon. You can also get a good calibration near the position 0 deg declination. perhaps 1 hour before or 1 hour past the meridian depending what side of the meridian your target is on.

Jerry Hubbell
Director Electrical Engineering
Explore Scientific, LLC.


Re: ASCOMPAD and PMC-8 Connection Problems

Mark Lamb
 

I got outside last night for a few hours before clouds, and PHD2 worked with my QHY5L-II-M, using QHY Camera", though tracking was not very good, ~1.9" error.   I was tracking M13 near the Zenith.  Looking at 60s exposures before and after engaging PHD2 showed a noticeable improvement, however.  

I wanted to get 1,2,3,4,5 min exposures to see how they compared, but it was clouding up noticeable during the exercise, with many PHD2 warnings during the 4 min exposure (loosing stars), so I only have 1-4 min to compare.  Although the conditions were rapidly deteriorating, and background sky color changing significantly, the star shapes of 4 min was close to that of the 1 min, upon casual inspection.

Having used PoleMaster for alignment, is PHD2 drift alignment needed?  (I did NOT.)

I only did the PHD2 calibration at my M13 target, near Zenith.  I recall that it is recommended to calibrate on stars near the horizon at meridian, which I definitely did NOT do.  Is this a problem?


Re: PMC-Eight Rate Offset Value in ASCOM driver setup is probably not correct for your mount

ji.theriot@...
 

So my mount , as Jerry mentioned, was having some PE issues.  And again as Jerry mentioned we noticed that my mount was showing a tracking rate error.  This is something I had kind of expected for quite some time but we were able to confirm that there was an issue after looking at some PHD logs.  After running a 30 minute Guide Assistant the RA trend line drifted up the entire time.  After some quick number crunching we realized that the offset of 0.023 should probably be -0.023 because my mount drifted at at rate of 0.046.

To find the ideal offset, I set a rate of -0.023 as per the conversation I had with Jerry.  After a rough polar alignment I ran a guide assistant and saw that the trend was now moving down on the graph, but not nearly as much as down as 0.023 was moving up, if that makes sense.  So I started tracking with the scope and activated the trend lines on PHD.  I confirmed that the RA trend was indeed trending down on the graph, so I made a change to to the offset to 0.00 as Jerry had recommended as a starting point.  I began guiding again and watched the trend line again, observing an upward trend.  I continued this adjustment process until the trend line was flat, arriving at an offset number of -0.0135.

The results show that the tracking rate adjustment has definitely improved my mount's guiding performance.  Prior to getting the tracking rate dialed in my mount would typically guide with an RA RMS error of 0.95"-1.00".  This was with an average PA error of <0.5'.  The night that I got it dialed my mount guided at 0.7" RMS in the RA axis even with a 6.92' PA error.  I also had 5 huge RA spikes (one that was > 40") that skewed that number.  Obviously that would tighten up significantly with a better PA and eliminating those spikes.  I hope to get some more time testing soon...if only the weather would cooperate.

Here is the image I did post adjustment: https://www.astrobin.com/297911/B/?nc=user
The stars were nice and round with no bloating.

Ji


Re: PMC-Eight Rate Offset Value in ASCOM driver setup is probably not correct for your mount

hubbell_jerry@...
 

Hi Bob,

I actually just wrote a knowledge base article about this and posted it here:


You can do a pretty good estimate if you were to use a cross-hair eyepiece and do the following procedure

Note: In the following measurement, you should have a way to record the RA value in decimal arc-seconds to a precision of at least 0.1 seconds in RA. Cartes du Ciel provides in the telescope connections dialog box.

1. Center a bright star in your scope right past the Meridian (RA coordinate a few minutes earlier than your     local Sidereal Time) and near 0 deg Declination.

2. Note the time you centered the star.

3. Note the RA coordinates your ASCOM application shows where you are pointed.

4. Wait at least 20 minutes.

5. Move your mount using the POTH or equivalent in RA to recenter the star in your eyepiece.

6. Repeat steps 2 and 3.

7. Calculate the difference in RA coordinates in Seconds

8. Calculate the elapsed time between the times recorded in step 2 and 6.

9. Multiply the value determined in step 7 by 15, i.e., 3.2 (sec) x 15 (arc-sec/sec)  = 48 (arc-sec).

10. Divide the value determined in step 9 (drift arc-sec) by the value determined in step 8 (elapsed time). This is the Rate Offset Value.

11. Determine the sign of the Rate Offset Value determined in step 10 by noting if the RA coordinate recorded in step 3 is "earlier" or "later" than that RA coordinate recorded in step 6. If the value in step 3 is "earlier" then the sign of the tracking is FAST and the offset should be NEGATIVE. If the value in step 3 is "later" then the sign of the tracking is SLOW and the offset should be POSITIVE.

This may seem a bit complex, but this is how it should be done.

I will add this procedure to the knowledge base article.

Thanks.

Jerry Hubbell
Director Electrical Engineering
Explore Scientific, LLC.


Re: PMC-Eight Rate Offset Value in ASCOM driver setup is probably not correct for your mount

Robert Hoskin <r_hoskin@...>
 

Oh!   Thanks for this!

What do you think the root cause of the variance is?  Gear tolerances?

Any idea how this applies to EXOS2 vs Losmandy mounts, and how someone who's not guiding might determine a correct value for their mount?  
[In other news,I see my mount head is being shipped back now, so I'll be back to figuring out its limits soon.  Good to know this, ahead of that.]


From: "hubbell_jerry@... [ESPMC-Eight]"
To: ESPMC-Eight@...
Sent: Thursday, June 14, 2018 10:34 AM
Subject: [ESPMC-Eight] PMC-Eight Rate Offset Value in ASCOM driver setup is probably not correct for your mount

 
The latest version of the PMC-Eight ASCOM driver has a parameter called Rate Offset under the Miscellaneous tab on the driver setup dialog box. I have set the default value of this parameter to 0.023 Arc-sec/sec based on the testing I performed on the PMC-Eight when developing this adjustment parameter. 

The purpose of this parameter is to allow you to finely tune your tracking rate to correct for any small error in your RA tracking when NOT USING and autoguider system. This only becomes an issue if you are doing astrophotography without auto-guiding which many beginning astrophotographers do.

The value of 0.023 Arc-Sec/Sec set may not be valid for your system. The problem was discovered when Ji Theriot was providing me PE data for his mount using PHD2. He provided me 30 minutes worth of tracking data without correcting the mount using PHD2 to allow me to analyse his mount's native PE. At that time his data showed that his RA tracking was drifting about 80 arc-seconds over a 30 minute period, which was equal to a drift rate of -0.044 Arc-Sec/Sec. 

The default offset value was not correct for his PMC-Eight. 

After some testing, he discovered that a Rate Offset value of -0.0135 was needed for his mount to properly track.He said that after doing this the mount tracks near perfectly.

I recommend that you set your Rate Offset value to 0.000 until you can test your mount's tracking rate using an auto-guiding system and PHD2 to measure the precise tracking rate error. Please let me know if you have any questions about this.

The next release of the PMC-Eight ASCOM driver will have the default for the Rate Offset Value set to 0.000.

Ji may chime in here about his experience and how he went about adjusting his Rate Offset Value.

Thanks

Jerry Hubbell
Director Electrical Engineering
Explore Scientific, LLC.






PMC-Eight Rate Offset Value in ASCOM driver setup is probably not correct for your mount

hubbell_jerry@...
 

The latest version of the PMC-Eight ASCOM driver has a parameter called Rate Offset under the Miscellaneous tab on the driver setup dialog box. I have set the default value of this parameter to 0.023 Arc-sec/sec based on the testing I performed on the PMC-Eight when developing this adjustment parameter. 


The purpose of this parameter is to allow you to finely tune your tracking rate to correct for any small error in your RA tracking when NOT USING and autoguider system. This only becomes an issue if you are doing astrophotography without auto-guiding which many beginning astrophotographers do.


The value of 0.023 Arc-Sec/Sec set may not be valid for your system. The problem was discovered when Ji Theriot was providing me PE data for his mount using PHD2. He provided me 30 minutes worth of tracking data without correcting the mount using PHD2 to allow me to analyse his mount's native PE. At that time his data showed that his RA tracking was drifting about 80 arc-seconds over a 30 minute period, which was equal to a drift rate of -0.044 Arc-Sec/Sec. 


The default offset value was not correct for his PMC-Eight. 


After some testing, he discovered that a Rate Offset value of -0.0135 was needed for his mount to properly track.He said that after doing this the mount tracks near perfectly.


I recommend that you set your Rate Offset value to 0.000 until you can test your mount's tracking rate using an auto-guiding system and PHD2 to measure the precise tracking rate error. Please let me know if you have any questions about this.


The next release of the PMC-Eight ASCOM driver will have the default for the Rate Offset Value set to 0.000.


Ji may chime in here about his experience and how he went about adjusting his Rate Offset Value.


Thanks


Jerry Hubbell

Director Electrical Engineering

Explore Scientific, LLC.





Re: ASCOMPAD and PMC-8 Connection Problems

W. Christopher Moses
 

I seem to remember that my QHY5L-II-M was pretty finicky also.  I'll be home in a few days and will check my notes to see if I have any info that might help you.

On Tuesday, June 12, 2018, 11:16:49 AM PDT, lamb_mark@... [ESPMC-Eight] wrote:


 

My PMC-8 has remained in the serial mode the last few times I have used it in the past week; each time having been totally powered down in between.  I have no idea why it was automatically reverting to wifi after power down the previous couple of times???  I will keep it in serial connect mode, though in the interim wifi had worked flawlessly for two nights last week, with the tablet ~3ft from PMC-8.  My previous wifi problems could have been caused by my tablet being 1-2ft away???


My ASCOMPAD continues requires the window to be visible and being "clicked" on for my XBox controller to move the mount, however.  PITA

I still have not done any PHD2 guiding, as PHD2 was NOT getting exposures from my QHY5L-II-M.  Yesterday, I played with PHD2 in my basement, and I still had some connectivity problems, but I was finally able to get the camera to work connecting it as "QHY Camera".  For some reason, connecting as QHY5L-II (???) would not work.  Hopefully, PHD2 will work the next time I have good weather.




 


Re: ASCOMPAD and PMC-8 Connection Problems

hubbell_jerry@...
 

Hi Mark,

That's good to hear that your PMC-Eight is behaving itself now. That really is a strange problem. I'm sorry I can't help you with the ASCOMPAD issue as I don't really have any time to investigate it. I think you said you posted the issue on the EQMOD group, but didn't get any good response there. All I can suggest is to maybe try it again.

Thanks for they update!

Jerry Hubbell
Director Electrical Engineering 
Explore Scientific, LLC.


What to do if you have a problem with your G11 mount while Auto-Guiding

hubbell_jerry@...
 

I have just posted an article talking about what you should do if you identify an issue with your mount's auto-guiding and/or periodic error. The article includes instructions on how to report any issue you may have to Explore Scientific Customer Service.


http://hosted.comm100.com/KnowledgeBase/My-ES-Losmandy-G11-mount-s-periodic-error-(PE)-is-higher-than-I-expect,-what-can-I-do-to-Improve-that-_A5000032.aspx?id=5000032&siteid=56501


Jerry Hubbell

Director Electrical Engineering

Explore Scientific, LLC.


Re: ASCOMPAD and PMC-8 Connection Problems

Mark Lamb
 

My PMC-8 has remained in the serial mode the last few times I have used it in the past week; each time having been totally powered down in between.  I have no idea why it was automatically reverting to wifi after power down the previous couple of times???  I will keep it in serial connect mode, though in the interim wifi had worked flawlessly for two nights last week, with the tablet ~3ft from PMC-8.  My previous wifi problems could have been caused by my tablet being 1-2ft away???

My ASCOMPAD continues requires the window to be visible and being "clicked" on for my XBox controller to move the mount, however.  PITA

I still have not done any PHD2 guiding, as PHD2 was NOT getting exposures from my QHY5L-II-M.  Yesterday, I played with PHD2 in my basement, and I still had some connectivity problems, but I was finally able to get the camera to work connecting it as "QHY Camera".  For some reason, connecting as QHY5L-II (???) would not work.  Hopefully, PHD2 will work the next time I have good weather.




 


Re: Exos-2 PMC-8 - pier extension & axes stabilty

Jennifer Shelly
 

Thanks Steve I will check it out.


Re: Exos-2 PMC-8 - pier extension & axes stabilty

Jennifer Shelly
 

Thanks Bob. I will definitely contact ES.


Re: Exos-2 PMC-8 - pier extension & axes stabilty

r_hoskin@...
 

Jennifer,

I have an EXOS-2/PMC-8, too.  If the clutches are locked, the wobble you are feeling will be the play between the worm and ring gears on each axis.  The two sets of teeth have either moved apart in use (the worm gear clearance is adjustable), or they left the factory like that.

My own mount arrived with very little play on either axis, but after some use, the RA loosened up. If you contact ES customer service, they can send you instructions on making the adjustment.  This problem recurred on mine after adjustment, and it is currently in Springdale (at ES's request!), undergoing what I fervently hope is a rejuvenation.  YMMV.

There is always going to be some imperfection in the way the ring and the worm interact on this design of mount, so some play will come with the territory.  If it's more than you're comfortable with, you can either adjust it yourself (ES can provide instructions, and Google is your friend), or you can ask ES if they'll do that for you. 

I think the key thing is whether the amout of play you're experiencing is stable, or increasing.  If it's stable and the mount is otherwise performing for you, perhaps you're ok.  If it's increasing/recurring (like mine was), you should probably reach out to ES CS and get some help.

The other thing is that, because of that pretty-much-inevitable mesh imperfection, people  developed the technique of balancing their scope 'east-heavy'.  Basically forcing the motors to drive 'uphill' all the time, so that the flanks of the gear teeth always mesh the same way, reducing backlash/play.  You will probably want to look into that as well. Lots of threads on that over on Cloudy Nights.

Hope this helps! 

- Bob


Re: Exos-2 PMC-8 - pier extension & axes stabilty

Steve Siedentop
 

The pier extension for the Orion Atlas EQ-G fits the Meade LXD-75, which the body of the EXOS-2 is based on.  It might be worth checking out to see if it fits the EXOS 2 as well.

-Steve

On Mon, Jun 11, 2018 at 1:01 PM drunkendogg@... [ESPMC-Eight] <ESPMC-Eight@...> wrote:
 

I forgot to let you guys know my name is Jennifer.


Re: Exos-2 PMC-8 - pier extension & axes stabilty

Jennifer Shelly
 

I forgot to let you guys know my name is Jennifer.


Exos-2 PMC-8 - pier extension & axes stabilty

Jennifer Shelly
 

I am going to preface this post with some information about me. The Exos-2 PMC-8 is my first mount. I began my journey with astrophotography a few months ago. I know enough about computers and electronics to be dangerous. Please keep this in mind if you respond.

I own a Exos-2 PMC-8 and I was wondering if it would be possible to get/add a pier extension to give my telescope some additional travel on the RA axis. If so, can someone provide me with some suggestions on how I can accomplish this.

Also, I have noticed that both axes have some wobble when the clutches are locked. The RA axis has the most wobble. Is this normal? If not, what can I do to add stability?


Re: loud noise

Brent Phillips
 

that was the fix thank you 

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