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Mesu mount (Mk1 and Mk2) owner's thread


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More and more people it seems are buying Mesu mounts, based on the excellent results and reports from longer term users. This is great! The more the merrier.

There are lots of questions, hints, tips and general discussion about the Mesu mounts.

I thought it would be a good idea to collate all of this valuable information into 1 thread to make it easier for current owners and potential purchasers to look for help and discuss their setups.

1 thing to understand is that the Mesu mount uses the Sitech controller  (v1 or v2) and software (Sitech.exe) from Sidereal Technology.

Some issues and discussions can centre around the controller and software, whereas the other discussions centre around the mount's mechanics.

I've learnt that a Sitech software issue isn't likely to be a Mesu mechanical issue and vice versa.

WIth this in mind, it's important to set up the mount mechanically first (balance, pier, cabling etc.) before attempting to problem solve if any Sitech issues come up. The mount is a friction drive (not direct drive as it has been described as before) therefore does not work in the same way as worm drives. It must be near perfect in both DEC and RA balance. Balancing DEC in all possible positions is important before RA is balanced.

It also has no natural rest position, i.e. not like a regular GEQ mount that you can point towards the NCP and it just 'looks right'. No, the Mesu can point anywhere in both axis and it will essentially look the same (without any scopes mounted).

Initialisation is key to using this mount, it does not know where it is pointing when first used, but once set up correctly, it should remember where it is each and every time.

The Sitech driver is good in the sense you can use it on a pc in simulation, without actually connecting the controller. This way, you can setup, sync, goto, slew and essentially try and 'break' it without actually affecting your setup. This is also a very good way to learn your way around the software without wasting time under clear skies, and getting cold at the same time.

There are plenty of owners with vast amount of experince, so ask and you will find there's lots of help available.

Of course nothing's perfect and there have been issues with both Sitech and Mesu products, but on the whole, I've not seen 1 person sell or otherwise move their mount on due to it 'not performing to expectations'.

Edited by Jonk
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You won't have any fun at all with it.  Turn it on - guide to sublime levels of accuracy - turn it off. Where is the fun in that!!?? Nothing to twiddle with, disassemble, degrease, repl

I am a Mesu Mk1 owner and was just pointed to this video (thanks  @wimvb ) about using an Ampere meter (needs to be able to measure DC current / Ampere, not only AC!) to balance a mount. As you know t

I've been meaning to have a look at the balance on my mount for a while and this thread pushed me to action yesterday. Following a bit of tinkering, I concur with @Zakalwe - the current readout in the

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I didn’t know you can use the Sitech software beforehand in ‘simulation’ mode. That is a very good idea for Mesu virgins like myself.

Also good idea for starting this thread 👍 

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Yes, when you install and run Sitech.exe you'll see scrolling messages showing its status. If it can't detect the controller it will say 'bad comms' or similar, and 'faking servos', in other words, simulating actual servo motors connected.

Have a play, get used to it and follow the various instructions about the setup, one of which I put on another thread (copied here to help, it's meant for actual mount setup, but ignore the part about aiming due E or W, just imagine that you have done this):

 

For those struggling, there is an easy way to offset init / sync. It does not matter where in the world you are, or what time of day it is, or even if you have the mount connected (faking servos mode, i.e simulation)

1. Make sure your latitude and longitude settings are correct in Sitech.exe

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2. Manually move your mount so it is pointing due E or W, by turning DEC only.

3. In Sitech.exe, open skyview.

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4. Click on a star on skyview nearest due E or W (depending which way you pointed your scope.

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This message will pop up - click Sync - the offset init screen will pop up next, and will auto close / auto sync within 15 seconds if nothing is touched. Press on the 'offset simple init automatic in x.xx' to stop the automatic countdown and syncing before you've had time to check things.

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5. Check GEM scope is looking East or West and choose the correct setting (mine are greyed out as it's set to EQ, not GEM as I have a non flip pier).

6. Click 'OK'. This will sync your scope's current pointing position to this star, which may not be totally accurate, but it's a very good starting point.

7. Using the handcontroller or slew arrows in Sitech.exe, slew to your chosen park position.

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9. Click 'setprk'. This will set the park position to wherever you are now pointing.

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10. Click Park (you can move the mount around first if you like, but if you don't then Park after a SetPrk before you power down, it won't remember the setting.

11. After syncing, setting a park postion, parking then powering down, everything should be fine when you power up and UnPrk - this should start the mount tracking and horizon limits and meridian settings will now be correct. And you don't need stars to do this!

On next power up, slew to your target, platesolve, sync the mount to the platesolve and it will be more accurate. The park position may change slightly mechanically due to the more accurate sync, but this is easy to reset.

With the encoders, there are 2 types - motor encoders that the Mesu mk2 does have and mount encoders, which are an option. You must turn the encoder settings to ignore if you don't have mount encoders. I'm fairly sure this page is nothing to do with the motor encoders.

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Hope this helps - you can play with all this in simulation, i.e. don't connect the mount.

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Edited by Jonk
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Any advice on getting perfect balance? even with the motors disengaged on the Mk2 there seems to be quite a lot of stiction in the system, if you give it a push it doesn't move far before coming to a halt, it doesn't spin freely like I would expect with the motors disengaged. not sure if this is normal or an issue with my mount, but it seems to be the same in both axis.

My method has been to give the mount a push in both directions and see how quickly it stops, and adjust it till it's about the same in both directions.

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1 hour ago, SamAndrew said:

Any advice on getting perfect balance? even with the motors disengaged on the Mk2 there seems to be quite a lot of stiction in the system, if you give it a push it doesn't move far before coming to a halt, it doesn't spin freely like I would expect with the motors disengaged. not sure if this is normal or an issue with my mount, but it seems to be the same in both axis.

My method has been to give the mount a push in both directions and see how quickly it stops, and adjust it till it's about the same in both directions.

On my e200, the RA spins very freely, but the DEC has some stiction, worse in some points of rotation than others.  I just balance it in a place where it spins more freely!

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Spare a thought for the Mk I owners who cannot disengage the drives, trying to get perfect balance (which TBH I didn’t think was critical on a Mesu).

Mind you, with 100+ kg all up weight,  a bit of stiction gives me time to react.

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2 hours ago, SamAndrew said:

Any advice on getting perfect balance? even with the motors disengaged on the Mk2 there seems to be quite a lot of stiction in the system, if you give it a push it doesn't move far before coming to a halt, it doesn't spin freely like I would expect with the motors disengaged. not sure if this is normal or an issue with my mount, but it seems to be the same in both axis.

I thought I had the same 'issue', as does my friend from up the road.

I liaised with Lucas Mesu by email with a video clip, and ended up sending him the DEC to check, thinking I had done something to it (too far out of balance perhaps?).

He checked it over, without charge and confirmed that it was within the limits he uses when he sets it up.

My RA also spins freely, as do they all - the RA and DEC axis cannot be made the same, else they would perform the same way. Don't forget, the RA is what tracks, the DEC does not (unless you want to set it up as an Alt-Az, but why?!).

On return the DEC still felt stiff, and not 'free' but he insisted it was normal. You need to be within 10Nm of torque to be in balance. Now I don't know who has a torque meter, but if your scope setup does not freely move in any direction in DEC, and you 'think' it's in balance, then it probably is. I mention all directions, not just one way then the other (90 degrees).

Try putting your complete scope assembly on its dovetail or plate on a steel rod, or broom handle, on a flat surface. Find the balance point and mark it or remember it.

Then rotate the assemlbly 90 degrees and do the same test. You should be able to find the centre of balance. Check 45 degrees too and really zero in. If the centre of balance isn't within the centre line of the dovetail bar in all directions, then you need to move back / forth / left / right or add weights so it is.

This way, you can be very confident that the balance will be good when you fit to the clamp (as long as you fit it so the centre of balance is in the centre of the clamp (i.e the 80mm hole).

Once the DEC assembly is balanced, refit, move so the scope is horizontal, or straight up then adjust the counterweights.

All being well, you should be able to move the scope is all directions, and always be within the balance required.

1 hour ago, tooth_dr said:

On my e200, the RA spins very freely, but the DEC has some stiction, worse in some points of rotation than others.

This is normal, don't worry - the tolerances will be tight, but nothing's perfect, that's impossible.

 

56 minutes ago, tomato said:

Spare a thought for the Mk I owners who cannot disengage the drives, trying to get perfect balance (which TBH I didn’t think was critical on a Mesu).

It is very critical, but you can balance using the method above without being on the mount.

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12 minutes ago, Jonk said:

This is normal, don't worry - the tolerances will be tight, but nothing's perfect, that's impossible

I wasn’t worried! Just telling Sam that this is normal for my mount. 

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I do like the OTA assembly on a roller approach, but I have just spent 2.5 hrs under a precious clear sky aligning the cameras so the dual rig is  staying where it is for now, guiding was 0.5" total RMS which is acceptable at my imaging scale.

And another thought, I have to disassemble the rig quite extensively to put it on and off the mount, (lifting two Esprit 150s on in one go is asking for trouble) so I will need to keep accurate records of where everything needs to be, but that shouldn't be too hard.

Will definitely try this method next time.

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Back on topic, the Sitech forum is always buzzing with discussion on controller issues/improvements/advice, quite a lot of the content is from Mesu owners.

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4 minutes ago, tomato said:

Back on topic, the Sitech forum is always buzzing with discussion on controller issues/improvements/advice, quite a lot of the content is from Mesu owners.

What issues are mentioned?  Either I am blissfully unaware of my problems or dont have issues.  

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I read the Sitech group forum a fair bit and from what I can tell, it’s mostly mount tracking limits and meridian flips that are catching people out.

Sitech is Dan Gray, so as you can imagine, it’s not always easy to convince 1 person to change his product.

Sitech is different to Eqmod which I assume most people will be familiar with, but it’s ok once you get used to it.

But, if it ain’t broke...

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1 hour ago, tooth_dr said:

What issues are mentioned?  Either I am blissfully unaware of my problems or dont have issues.  

Software interfaces with Nina etc..  seem to crop up a lot, particulalry as Jonk says around MF and mount limits.   

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16 minutes ago, Laurin Dave said:

Software interfaces with Nina etc..  seem to crop up a lot, particulalry as Jonk says around MF and mount limits.   

I was about to migrate to NINA, to allow coordinated dithering.  I'll have to keep an eye out for problems and solution.

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22 minutes ago, tooth_dr said:

I was about to migrate to NINA, to allow coordinated dithering. 

Do you feel you need to dither? If you're doing long exposures, say 20 / 30 minutes, then it's unlikely you'll get all your data in 1 night, even with 2 scopes.

If you decrease your plate solve accuracy slightly, you won't end up pixel perfect on the next platesolve the next night, which will naturally introduce dither night by night.

Each camera will be different so assuming the same filter on 2 scopes, same FOV and image scale etc, dithering probably won't be required. I suppose you could try each and every scenario to see what works.

I tried NINA but it won't work with my focusers (or didn't at the time).

Voyager is another option, but that's a different subject all together.

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17 minutes ago, Jonk said:

Do you feel you need to dither? If you're doing long exposures, say 20 / 30 minutes, then it's unlikely you'll get all your data in 1 night, even with 2 scopes.

If you decrease your plate solve accuracy slightly, you won't end up pixel perfect on the next platesolve the next night, which will naturally introduce dither night by night.

Each camera will be different so assuming the same filter on 2 scopes, same FOV and image scale etc, dithering probably won't be required. I suppose you could try each and every scenario to see what works.

I tried NINA but it won't work with my focusers (or didn't at the time).

Voyager is another option, but that's a different subject all together.

Is dithering not essential to CMOS cameras?

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13 minutes ago, Jonk said:

I don't know, I don't use one. But the same target on multiple nights will still introduce natural dither?

Ok, my two cameras are CMOS IMX571, taking 2-3 minute subs, broadband.

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Ok, I would just ask, what happens if you don't dither vs you do? Is there a noticeable difference in the stacked result? Are you imaging OSC?

For such short exposures, maybe just leave as is - dither the main camera every 3 or 4 subs,. but lose maybe 1 sub on the other camera - that's 7 out of 8 good subs every half an hour? Might be better than changing the entire software control of the imaging which may present other unknown issues and more hair pulling.

Or, do that, but install NINA on a laptop / second PC. so you can experiment safely.

I've not tried to control the Mesu via NINA, so cannot comment on that.

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7 hours ago, tooth_dr said:

What issues are mentioned?  Either I am blissfully unaware of my problems or dont have issues.  

Same here, I followed the tried and tested advice on SGL to install and set up Sitech Config and Exe and have had no issues but then I don’t use half of the functions that are available via the software and controller. Of course, there is a whole host of astronomers on the forum who use Sitech to control a variety of different scopes and mounts.

On the dual rig I am using NINA on two laptops and dither every 3 x 3 min subs on the ASI 178 RGB camera as walking noise is quite noticeable without dither. That means I’m currently losing 1 in 3 Lum subs, but I will experiment  with pushing the interval out to 1 in 4 or 5 as there was no appreciable walking noise on my last outing.

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Hi @Jonk

So managed to download the Sitech software and been playing with the current version of it, think it is 94nWin. It then opens up skyview and after doing want you suggested, a simple offset init it seems to just track. Moved the mount to other parts of the sky without any issue. Explored the 'change config' and scope info and set location, seems fairly basic.

One question though, what do I set the Mount Parms to, is it an EQ or GEM mount, as when selecting the EQ mount the GEM functions grey out and can't be selected?  

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Also another query guys,

The PointXP software that I guess is similar to what Tpoint does in the sky10 software, how do you add points to it? I open the PointXP application but there doesn't seem a way to add calibration points, I'm using CdC by the way. Do I have to use Skyview for PointXP to work?

Cheers,

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Ok, firstly you should update the Sitechexe software from this link http://siderealtechnology.com/SiTechSetup095G.exe

Then once installed, overwrite the sitechexe.exe file with that from this link http://siderealtechnology.com/SiTechExe095H.zip

These are the latest as of today. They are not listed on the main website, as they are classed as beta and rely on user's testing and feedback.

The sitech website is not maintained very well, and you'll find more information on the groups.io Sitech forum.

They will list any updates to the software, and it'll be up to you to decide whether to use it or not.

Make sure you backup your controller configuration (config.car I think) as this will have all the settings unique to your mount, as Lucas sets all this up before he despatches the mount.

Another thing you can do if you want, is upgrade the controller firmware...but only if you feel you want to / need to.

http://siderealtechnology.com/V39.BIN

http://siderealtechnology.com/V97.BIN

That aside, if you have a tripod or pier that is set up as a standard GEM, i.e. you must do meridian flips, or you can crash into the tripod or pier, then GEM is the right choice.

If you have a bent knee pier, and you cannot crash into anything, then either option will work, but the EQ option removes meridian limits as a flip is not required.

Regarding a sky map, if you have the ability to platesolve and are guiding, then a skymap is not necessary and probably a waste of time.

I believe @Skipper Billy went though this exercise if I remember corrently?

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Again @Jonk great advice.

Just to be clear I don’t have my mount yet so this is in the virtual world for me at the moment, it is fun though doing a Goto and seeing the mount ‘virtually’ move to its target. Must say these Mesu mounts are very quiet 😊😉

Duly noted regarding the software update, I did wonder when it said it was a 2017 version on the main website. And will check the GEM option as it will be mounted on a standard pier.

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On 12/02/2021 at 09:04, SamAndrew said:

Any advice on getting perfect balance? even with the motors disengaged on the Mk2 there seems to be quite a lot of stiction in the system,

Great thread thanks Jonk and others for the information, you never stop learning.  Being told I have spanner hands, I generally struggle when a sensitive touch is needed so I acquired a cheap spring balance which works great for balancing these mounts.  As has already been said, both of mine have differing levels of stiction in different places as you rotate the RA & Dec axis even with the motors disengaged, but as Lucas says this is normal for these drives.

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