Date   

Re: Mesu 200 Mk2 Tracking stops close to equator

Jose Ignacio Sanchez Rodriguez
 

Thanks Paul,

Couldn´t agree more


Re: Mesu 200 Mk2 Tracking stops close to equator

paul K
 

Torben, Jose and all,

It's really good that Roland and Yan-Eric have made suggestions about fixes. However, I would suggest caution and a completely systematic approach if you decide to experiment with settings which are different from those recommended by the manufacturer. Presumably MESU Optics ran extensive tests (?) to determine the appropriate Sitech parameters for a mount with a 100Kg(?) payload. I would only make changes if Mesu Optics agrees them. Personally, I think making changes like this is potentially a minefield and also potentially very protracted and frustrating if you don't have Dan's level of understanding of sky geometry, electronics and programming.

It's very much personal I guess, but based on my 9 years experience of programming astro solutions and working with various manufacturers equipment, it's going to be tough if you start to vary manufacturer's specs. You might get lucky, but for me, If my MESU didn't work when I purchased it in 2015, I'd be wanting the manufacturer to fix it. Also pragmatically, these things are massive and shipping back to the manufacturer is problematical, so if the manufacturer wants to fix it by suggesting changes in situ that's fine, but I don't think it's fair or useful to start experimenting at a personal level without supervision and suggestion from the manufacturer.

In my experience in software testing (in which I've been involved in one way or another since 1974) and relating that experience to this situation, it's possible to fix a problem which shouldn't be there by changing parameters to make the problem disappear. Subsequently, the problem changes slightly and the previous fix needs a tweak and so on. So it's really important to root cause rather than apply workarounds and this can only be done with manufacturer's input. It's important that the manufacturer works with you to solve the situation, and the solution is then for them to apply across their range of products. IMO you don't want an individual solution for each mount, that's not a quality assured approach.

good luck,
Paul

best wishes all
Paul


Re: Mesu 200 Mk2 Tracking stops close to equator

Yann-Eric Boyeau
 

Hi Torben,

Looking at the graph of the Guiding assistant, it is easy to see that you have a nice negative and constant drift of 5,8 arcs/min.
I think the ticks/rev configured for your mount are wrong.
If you show this graph to Mr Mesu, he will explain how to fix this. You have to use servoconfig.

I used to have some drift with my Mesu200 and I managed to correct the number of ticks.
This SGL post also explain how to do it :  https://stargazerslounge.com/topic/247247-mesu-200-ra-guide-speed-correction/. Ticks/rev can vary with temperature, load and tension. I iterated the correction until I got no more tracking improvement in guiding assistant.

I understand your frustration at this point. I live 22 000 km from Netherlands and did not have the option to sent back my mount... so I fixed it. And I am happy with it now.

Sorry you had a bad experience with Mesu.

YE


From: Sitechservo@groups.io <Sitechservo@groups.io> on behalf of T. van Hees <torben@...>
Sent: Thursday, February 18, 2021 02:44
To: Sitechservo@groups.io <Sitechservo@groups.io>
Subject: Re: [Sitechservo] Mesu 200 Mk2 Tracking stops close to equator
 
Hello again. I am grateful for all the assistance I got in this community, so here is my most recent data. In the link you can find two of my recent guiding logs. Many of the log parts are with dithering because I just let Voyager run for the rest off the night, as I could not get the drift under control. I just took very short exposures with the RASA so got some data nevertheless. There is one run of Guiding Assistant, also attached as a screenshot. Within the logs, there is one run where DEC stops responding to guider commands: This is due to me not correctly tightening a clutch, not a mount error.

You will find RA drift between 2.5" and 14"/minute as well as some 20-30s spikes. I have tested again with a lighter and proven setup (my RC8 with OAG). I have currently no access to the log but I can describe the results: The 30s-spikes are far smaller, barely detectable (0.2" instead of 1"), but the RA drift was the same. DEC always seems to correct fine with both setups. That same setup works without problems on a Heq-5, so I think I can safely ignore a flex error. I realise longer logs might be beneficial to diagnose what exactly is wrong with the mount, but I can not present those. I have no more interest to tackle this problem and am in the process of contracting a Dutch lawyer to try and settle the whole mess for me and cut my losses. Dealing with Mr Mesu has been tedious and exhausting. I want nothing more to do with him and his business. I feel sorry that more people than just me are affected.

Links to logs:
https://www.icloud.com/iclouddrive/0_WQwxyB10KaGZzi4k3u6WY1g#Mesu


Re: Our Ice Storm and Power Outage

paul K
 

you obviously had quite a storm Dan - the weight of ice on those trees had a big effect.
It looked like a beehive at one minute in on the left?
Keep warm,
Paul


Re: Mesu 200 Mk2 Tracking stops close to equator

paul K
 

I agree with what Don has said here about Voyager. Keep the variables under control, use just Sitech and PHD2. I would also add, for a systematic approach, don't change anything else now. Let's see if the Sitech/ MESU/ PHD2 and Sitech/ CEM60/ PHD2 runs show any differences. If the runs show differences in tracking performance, I think this points to the MESU mount. It's then down to trying any relevant changes which might sort the problem with the MESU.
I hope this helps,
Paul


Re: Our Ice Storm and Power Outage

Don W
 

Hi Dan,
I watched the video, that was a lot of crunching ice and amazing number of trees and branches that fell.  I am glad to see you and Sam doing well.  Stay well and warm.  Even your dog was wearing a sweater.
Don W


Re: Mesu 200 Mk2 Tracking stops close to equator

Jonk
 

I have another suggestion that may be a small check but worth doing nonetheless.

Check all of your motor encoder and power connections are clean, free from any moisture or green 'rust' and check that all the connections are good.

If any one of these isn't making good contact, it could affect things - best to eliminate all outliers.


Re: Mesu 200 Mk2 Tracking stops close to equator

Don W
 

Hi T,

To really evaluate drift, especially RA drift you need to stop using Voyager.  I have nothing against Voyager, but it is a third source of potential problems that simply confuses your tests.

SiTech controls the mount directly - you can not turn it off and operate your mount.  SiTech works for everyone else in this world, but the settings must be proper.  PHD2 can be used as a tool to evaluate drift and also guiding capability and guiding accuracy.

First realize that Sidereal tracking only occurs near the zenith.  Also Sidereal tracking depends on GOOD polar alignment.  Doing tracking on both sides of the meridian (looking east and looking west) will check your balance as a factor.  You can use PHD2 to measure drift in both axis by turning the aggressiveness to zero.  Doing this with only SiTech will check the basic settings in SiTech.  If the tics/rev setting are wrong in SiTech, there will be drift - but only near the zenith is sidereal tracking accurate.

If your polar alignment is way off, do the drift test I outlined about 6 hours later.  The drift results due to PA will be different.

Don W


Re: Our Ice Storm and Power Outage

Joshua Hufford
 

That is some serious ice!

Stay safe, glad you have power back now. 

Josh

On Wed, Feb 17, 2021 at 10:36 AM Dan Gray <grayarea@...> wrote:
Hi all,
Sorry I've been missing in action.  We lost power Friday night, and finally got power back last night.
We've been living in Samantha's RV.  Now that we have I-Net again, I'lll get caught up on emails.

Here's a video of our Ice Storm.

Dan


Re: Mesu 200 Mk2 Tracking stops close to equator

Jose Ignacio Sanchez Rodriguez
 

Hello Paul,

Yes, I will first run the GA with the Mesu and only then try it with the CEM 60 on the same area of the sky.

The more I think about the guiding behaviour and the RA reading behaviour I saw in the video, the more I lean towards the idea of the problem being either balance or the RA servo not working well.
I´ll just toss my reasoning here. Please let me know if it is wrong.

What I see is that the RA reading on SiTech.exe is decreasing. As I understand this, RA increases EASTward, so the mount´s driver is telling me that the mount is actually moving WESTward faster than sidereal. This cannot be due to the guiding commands cause they are EASTward. So it has to be either the setup being scope heavy (I am west of the pier) or the RA servo not working well. That would also explain why the mount does not respond to the guide commands. 

Best Regards,

Jose


Re: Mesu 200 Mk2 Tracking stops close to equator

Roland
 

Torben,

Sorry to hear that you’re having so many problems.  

If you are getting constant drift in one direction then there are not many possible causes. Namely:
  • Poor polar alignment.
  • Wrong tracking rate.
  • Significant imbalance of the mount which may be causing some slippage.  This would not normally be an issue with a worm/crown gear mount but, as far as I can understand, the Mesu mount has some sort of clutch for the direct drive.

If you are getting jumps superimposed over the drift, then I can only see the following possible causes:
  • Mechanical problems with the mount.
  • Guiding overshoot (if you’re guiding).
  • Guiding which is trying to follow the seeing because guide exposures are too short.
  • External factors such as wind.

I don’t know if you have done this yet but I suggest you try to graph your drift without applying any guiding corrections at all.  Do not use a mount model.  In Maxim, you simply set the mount to guide, set aggressiveness to zero and do a tracking graph over several worm cycles.  This means you will get the periodic error superimposed on the drift and quick jumps but you should essentially see a line which goes in one direction with respect to time.  With SiTech you can adjust the tracking rate based on the following note from Dan (which I posted a few days ago):

"If it ALWAYS drifts the same amount for anywhere in the sky, I would check my ticks per rev, also use a time server, and software that keeps updating your clock.

You can manually edit your SiTech.cfg file (make sure you're not running SiTechExe when you edit the file).

Look for the variable labeled "RightAscensionRate=0"
Change the zero to whatever you want.
This is in arc seconds per second, can be negative.
Dan”

This is a little laborious because you need to close SiTech each time, alter the config file and start SiTech again but you can get the hang of it fairly quickly.  If you can tame the drift then you will be left with the jumps and the PE.  The PE you can correct by guiding but the jumps are potentially a major hurdle if they’re due to mechanical issues.  Correcting fast jumps is very hard.  About the only thing you can do is to use an adaptive optics setup but this means extra costs and messing around and to correct quickly (say, at a few Hz) you need quite bright stars.

Hope this helps.

Roland.



On 17 Feb 2021, at 16:44, T. van Hees <torben@...> wrote:

Hello again. I am grateful for all the assistance I got in this community, so here is my most recent data. In the link you can find two of my recent guiding logs. Many of the log parts are with dithering because I just let Voyager run for the rest off the night, as I could not get the drift under control. I just took very short exposures with the RASA so got some data nevertheless. There is one run of Guiding Assistant, also attached as a screenshot. Within the logs, there is one run where DEC stops responding to guider commands: This is due to me not correctly tightening a clutch, not a mount error.

You will find RA drift between 2.5" and 14"/minute as well as some 20-30s spikes. I have tested again with a lighter and proven setup (my RC8 with OAG). I have currently no access to the log but I can describe the results: The 30s-spikes are far smaller, barely detectable (0.2" instead of 1"), but the RA drift was the same. DEC always seems to correct fine with both setups. That same setup works without problems on a Heq-5, so I think I can safely ignore a flex error. I realise longer logs might be beneficial to diagnose what exactly is wrong with the mount, but I can not present those. I have no more interest to tackle this problem and am in the process of contracting a Dutch lawyer to try and settle the whole mess for me and cut my losses. Dealing with Mr Mesu has been tedious and exhausting. I want nothing more to do with him and his business. I feel sorry that more people than just me are affected.

Links to logs:
https://www.icloud.com/iclouddrive/0_WQwxyB10KaGZzi4k3u6WY1g#Mesu
<Drift4.PNG><Drift3.PNG><Drift2.PNG><Drift.PNG>


Re: Mesu e200 bent knee pier - GEM vs EQ

Dan Gray
 

Hi Jonk,
Here's an image with settings.  Look carefully on the right side, you'll see the meridian flip lines.
In the upper left is the settings:


On Wed, Feb 17, 2021 at 7:31 AM Don W <westergren@...> wrote:
Hi Jonk,

A GEM is not a FORK/Equatorial.  It really is best to use a GEM as a GEM.

Set the Meridian West to 90° and leave the Meridian East at zero.  That will make all motion looking east with counter weight Down, and all looking west counter weight Up.  The mount will never do a meridian flip.

Set your altitude limit to whatever you want, either with the fixed alt limit in Mount Parms or using the SiTech.hrz file.  Generally astrophotography is badly affected by refraction below 30° altitude.  However you can move below the altitude limit with the handpad to set a lower Park position if desired.

DEC motion is either North (toward the North Pole) or South toward the South Pole.  If you move toward a Pole from above, when you get to the pole, the DEC motion reverses when pointed BELOW the pole.  This is true regardless of a GEM or EQUATORIAL.  Parking at the pole is truly ambiguous and will cause you problems.  Parking at the pole can not initialize RA.

The reversal of Dec you experienced when set as EQ is exactly why I say don't set it as EQ.

Don W


Re: Fw: Coord issue? Video attached via dropbox

Dan Gray
 

Sounds like the guider was keeping it centered, and either there's a setting wrong in the SiTech.cfg file, or polar alignment/slippage.
Here's what to look for in the SiTech.cfg file.
Make sure you edit the SiTech.cfg file when SiTechExe is not running
Also motor ticks per rev could be wrong,
Balance and roller pressure are critical.

RightAscensionRate
DeclinationRate
They should both be zero.
The reason I mention this possibility, is this got changed somehow in someones config file.

Dan



On Thu, Feb 11, 2021 at 10:12 AM jaspal <jaspaltheknight@...> wrote:



From: Jaspal Chadha <jaspaltheknight@...>
Sent: 11 February 2021 16:29
To: Sitechservo@groups.io <Sitechservo@groups.io>
Subject: Coord issue?
 

Hi all,
                Can I please pick your brains? so as you are aware I have been having issues with my Mesu Mark 2 mount  drifting every second in RA making it unusable or guidable at times. After in contact with Lucas Mesu and problem solving I changed to a new computer, rebalance and cable management, it's early days to say 'WHOOP WHOOP problem solved' but yesterday it went fine for the hour and half i had ( only tested in the WEST )

I use Voyager software that controls everything and all the drivers are up to date

I start voyager, mount is pointing WEST

Sitech showed the mount as tracking.... 'I completed a Plate Solve Actual Coord' and the Sitech box appeared and press INIT to confirm ( making sure the bottom bit showing WEST) and then press SYNC in voyager and the RA and DEC readings are the same... 

Voyagers allows you to search for target and uses ALADIN to show what image looks like in your pre-defined FOV setup, You can also free search around sky screen and do a precise Goto which will plate solve the target.   

Last night I choose target NGC457 and it slewed in bang onto to my FOV I then began PHD2 guiding and was at around TOT 0.50. 

After consistent frames  perfectly centred  I pressed the 'Get telescope position' It showed that the scope had moved considerably away from the target, however each frame it was still bang in the middle of the FOV and guiding graph good.

see images below ( first image shows R.A 01:18:11:8 and DEC 58:23:41 in SITECH ) and the in Voyager RA 01:18:12 DEC 58:23:41)




Second image shows actual telescope position within 30 mins or so of imaging




Third image shows the actual sub frames coming out which is dead centre and not repsentative of image 2 (above)  




The developer of Voyager states, usually mount work in JNow or you have done a wrong sync or not right epoch seems & can't help further 

Could this possible be causing RA drift, something clashing? 

Thanks in advance 


Re: Mesu 200 Mk2 Tracking stops close to equator

T. van Hees
 

Oh, it seems one has to register to be able to download those logs. Did not know that. 


Our Ice Storm and Power Outage

Dan Gray
 

Hi all,
Sorry I've been missing in action.  We lost power Friday night, and finally got power back last night.
We've been living in Samantha's RV.  Now that we have I-Net again, I'lll get caught up on emails.

Here's a video of our Ice Storm.

Dan


Re: Mesu 200 Mk2 Tracking stops close to equator

T. van Hees
 

Hello again. I am grateful for all the assistance I got in this community, so here is my most recent data. In the link you can find two of my recent guiding logs. Many of the log parts are with dithering because I just let Voyager run for the rest off the night, as I could not get the drift under control. I just took very short exposures with the RASA so got some data nevertheless. There is one run of Guiding Assistant, also attached as a screenshot. Within the logs, there is one run where DEC stops responding to guider commands: This is due to me not correctly tightening a clutch, not a mount error.

You will find RA drift between 2.5" and 14"/minute as well as some 20-30s spikes. I have tested again with a lighter and proven setup (my RC8 with OAG). I have currently no access to the log but I can describe the results: The 30s-spikes are far smaller, barely detectable (0.2" instead of 1"), but the RA drift was the same. DEC always seems to correct fine with both setups. That same setup works without problems on a Heq-5, so I think I can safely ignore a flex error. I realise longer logs might be beneficial to diagnose what exactly is wrong with the mount, but I can not present those. I have no more interest to tackle this problem and am in the process of contracting a Dutch lawyer to try and settle the whole mess for me and cut my losses. Dealing with Mr Mesu has been tedious and exhausting. I want nothing more to do with him and his business. I feel sorry that more people than just me are affected.

Links to logs:
https://www.icloud.com/iclouddrive/0_WQwxyB10KaGZzi4k3u6WY1g#Mesu


Re: Mesu mark 2 RA drift update

Don W
 

Hi Jonk and all,

Balance in DEC must be done in two orientations:  Horizontal scope and vertical scope.  This is especially true when there is ANY non-symmetrical installation of scopes or multiple scopes, guide scopes, or cameras.  It is true that balance in Dec should be done before balancing RA.

Don W


Re: Mesu mark 2 RA drift update

gary neilson
 

Hi All,

Its concerning to read all of these RA problems with the Mesu Mk2. I have the mount (received October last year.) and haven't had any of the issues fortunately.

It makes me wonder if the new clutch system of the Mk2 is part of the issue? As motor spacing is critical, I always make sure the lever is pressed firmly to lock the motor in place. Similarly for the axis clutches as any additional friction would mess things up. 

Other steps I've taken include:

  • Acceleration. Reducing the acceleration parameter in servo config by half which is probably very conservative. This prevents possible slip at the beginning or end of a slew.
  • Balance. Ensuring its balanced in RA/DEC off the mount. I address any off-axis loads that would exceed the torque spec of 10NM (even though it appears balanced when the CW bar is vertical or horizontal). As an added check I've found if I run guiding assistant in PHD2 and I see any backlash, its likely some minor slippage is occurring - I tend to ignore this if its small and do not compensate for it in PHD2 settings. Repeating the calibration and measurement in a different part of the sky clears it so certain angles do have an impact it appears. 
I used to use the dowel method described by Jonk. But now use an old Wii balance board (luckily its survived our  last move!) and software I found for a project at the University of Colorado. Its much safer as I simply place the scope/accessories on the board and adjust until the COG is centred in the reticle! No more wobbling of heavy equipment while finding the fulcrum!

Cheers

Gary.


Re: Mesu e200 bent knee pier - GEM vs EQ

Don W
 

Hi Jonk,

A GEM is not a FORK/Equatorial.  It really is best to use a GEM as a GEM.

Set the Meridian West to 90° and leave the Meridian East at zero.  That will make all motion looking east with counter weight Down, and all looking west counter weight Up.  The mount will never do a meridian flip.

Set your altitude limit to whatever you want, either with the fixed alt limit in Mount Parms or using the SiTech.hrz file.  Generally astrophotography is badly affected by refraction below 30° altitude.  However you can move below the altitude limit with the handpad to set a lower Park position if desired.

DEC motion is either North (toward the North Pole) or South toward the South Pole.  If you move toward a Pole from above, when you get to the pole, the DEC motion reverses when pointed BELOW the pole.  This is true regardless of a GEM or EQUATORIAL.  Parking at the pole is truly ambiguous and will cause you problems.  Parking at the pole can not initialize RA.

The reversal of Dec you experienced when set as EQ is exactly why I say don't set it as EQ.

Don W


Re: Mesu 200 Mk2 Tracking stops close to equator

paul K
 

I think you're right Jose, the same rig on a different mount isolates the one variable we're interested in; you'll prove the performance of the kit and that will just leave the mount. I think this exercise will produce valuable evidence.

As you identified, perform the trial in the same area of sky where you had the problem.

It might be worth doing the guiding assitant trial before switching to the other mount, just so you're testing the current context before making any change. Then change to the other mount and repeat.

Good luck,
Paul

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