dan_adi

I will test tonight if it s clear. If I’m too close that means good news, just add some spacers

The setup is like this: field flattener + 2 mm connection + ONAG + 2 mm connection + filterwheel + g3 16200 camera

required distance for field flattener about 87 mm

ONAG needs about 66 mm

g3 16200 + filterwheel needs 33 mm

So I am too close?

Hey guys, I have a 140 mm APM APO refractor with a TS field flattner. I also use a ONAG for on axis guiding. With the ONAG i'm over the recommended distance for optimum use of the field flattner. Because of this (I think) I get stars with coma at the edge of the field. Is this the problem or should I look for something else too? with the refractor I was hopping for pinpoint star near the edge of the field of view.  I have attached a image from last night  (raw).

On 29/09/2019 at 20:34, Fellside said:

Hi Dan

Thank you for the screen shots.

I will be rearranging my rig soon, I will try out your method and settings. Hopefully I to will get a more accurate model.

Many thanks

Graham

Welcome. Hopefully next week I will install a new pier and the apm refractor on the mesu. I think with a refractor I will get consistent modeling results. As soon as I am up and running I will review the tutorial. 

Ignore mode when modeling, Polite mode when imaging 

the settings

Yes, tomorrow I will post an image, no problem.

56 minutes ago, Star101 said:

Hi Dan,

Thank you for taking the time to create this PDF. You have put some very interesting bits of information in there. I will re read and check my Mesu settings to see if I can improve the guiding. Although I do not use modelling, I do use Plate Solving and have very few issues. However, there are some interesting pointers in there that I would like to try out. Every little bit helps. 

Thanks again.

Hello, 

Sharing the information will make life easier for everybody. This is not an easy hobby, but very rewarding when you make something work  . THe model should make guiding even easier (in theory) but I have’t tested yet (bad weather, and I’m replacing my brick pier with a steel one). As soon as I can I will test guiding and even how much I can expose unguided with a model.

Have a nice evening

1 hour ago, Fellside said:

Hi Dan,

Very interesting. Thank you for taking the time to do this.

Can I ask what load you have on your Mesu. I have about 35kg plus balance weights. I will soon be adding a second scope to this (9kg) I have never had to my knowledge any slip on the drive. I run all settings as supplied by Mesu. As you found balance can be done by feel along and I find it gives acceptable results. If you make any changes to you image train you will need to resemblance and in theory redo your mount model. 

I usually do a plate-solve sync and slew to the object.  Great Mount😀

Regards

Graham

 

Hello, I have a 12 ich SCT F8, Moravian CCD with FW, ONAG, Leo focuser, Asi 183 (for autoguiding), top plate, intel nuc, pegasus astro,  I think about 40 KG. And a 140 mm APM refractor which I haven’t mounted yet. You won’t notice the slip because it’s very small. Because the supervisory threshold default value is 10 degrees the scope encoders will never correct the position of the motor encoders because the disagrement between the 2 will never be that high. If you lower the supervisory threshold by the recomended setting in the sitech manual (2x resolution of the scope encoders e.g 4 arcminutes ) and not lower the accelaration accordantly you will see the effects of small cumulative slip and unbalance (the mount will start to oscilate , go into blicky mode and stop all movement). For me it was a learning experience. Offset init without cal inits (model) and platesolving works just fine, I totaly agree. I just think this mount could reach it’s maximum potential with a model.

Hello,

For all the Mesu 200 mount users, I wrote a little tutorial regarding mount modeling. After a good feedback from Mr. Dan Gray and Mr. Steve Richards I decided to share it on the forum. Please feel free to add any suggestions or corrections as I'm just a beginner in this wonderful hobby 

Mesu_200_modeling.pdf

The house is built ok, no vibrations with traffic. Also it’s in a rural zone, no heavy trafic. So I don’t have to panic over a couple of arc minutes variation in aligment. Thanks for clearing things up

Hey guys, in the last few days I noticed my polar alignment keeps changing. I’ve build a small observatry ontop of my house. The pier is made of brick and cement. Do you have any iddeas as to why I am losing my polar alignment in 2-3 days. A couple of days ago I had an error reported by phd asistant below 1 arc minute and last night 5 arc minutes. Could it be the pier? Everything is bolted down, I have double and triple checked. It’s getting frustrating

I have made some progress with the mesu modeling. After a long and painful :)) drift align in phd2 and a modification of the supervisory threshold in sitech config, I rerun the model with only 20 cal points cause I was sleepy and behold I've got a total rms value of 27.3 " (thats arcseconds :) ) with only 1 outlier eliminated.

So as a conclusion the Mesu 200 can be modeled and has great pointing accuracy. In a  few days I will write a tutorial with some pictures of sitech configuration for fellow mesu users.

Clear skies everybody!

I will try the spring ideea and see if it adds some objectivity to balancing. The clock issue with the sitech controller is not because of sitech. As I understand the internal controller clock is much more accurate than the pc clocks. Because of these differences, in a short time there will be a disagrememt between the 2 clocks and the tracking will suffer. A while ago mr Dan Gray updated the sitech software to automaticly compensate for the time difference between the 2 clocks, but you still have the main issue -> an innacurate pc clock. So in order to benefit from the best tracking your mount can achive it would be best to have an accurate pc clock

do you guys know any precise way to balance the mesu? I tried to look at the current amps in sitech.exe while manualy slewing but the current varies to much to get a consistent answer for comparison. I was thinking of a hand scale to measure the force applied while moving in dec or ra. Any other ideas?

The above link works, it just takes 2 minutes to load, they are lots of pictures so it takes time.

The usb cable connection with the pc that runs sitech.exe is just a one time operation. If you have just one utp cable in your observatory you can buy a small 4 port switch. If you only have wifi acces, you can connect the time server to the router in your house. As long as the wifi is on the same LAN you can connect to the time server. My time server is in the house not the observatory. Is it clear? My english is rusty.

the link with the ppt presentation takes a while to load, if not you can find it in the sitech yahoo groups

Sidereal technologies makes a small time server (sitech time server). It’s easy to configure, and it connects to about 12 gps sattelites. It has a precision of about half a milisecond. It even sends the gps coordonates to sitech.exe. I set mine to update the pc clock at 15 sec intervals. This is the link from mr Dan Grey http://siderealtechnology.com/IncreasingTheAccuracyOfYourTelescope.ppt 

I must admit I was pretty stuborn regarding modeling the mesu, I did not give up easily, and from what feedback I got from the sitech yahoo group, 40 arc sec seems pretty good. Direct drive mounts with absolutes encoders have below 20 arcsec or below 10, but who has the cash :))), one can only dream, maybe at retirement :). The limit I think in the case of mesu 200 is some small small slip which is not detected by the scope encoder that has a resolution of 2.1 arcmin. With a better scope encoder the pointing could improve. 

Hello guys. I managed to get a good mount model for the Mesu 200 mount and I thought I should share my experience. I had great advice on the sitech yahoo groups from mr. Dan G. and mr. Don. The sitech controller uses active pointxp modelind and platesolve 3 engine, the same ones planewave intruments uses for their mounts. At first, searching the forums, I did not find any mesu user to have succesfully made an acceptable model, the reason beeing some mount slippage with this friction drive. I don’t know how much slippage there is but that was the reason put forward. The steps I took are:

1. For accurate tracking and modeling time synchronization between sitech controller and pc clock is essential. The pc clocks are usually bad at keeping time with an accuracy of miliseconds. In order to fix this there are 2 methods: a. A less precise one is using software to syncronize the pc clock with an online time server. b. A more precise method is to buy a small time server. I tested both methods and the dedicated time server  was much more accurate and stable. I set my pc time update from the time server every 15 seconds. There is a powerpoint presentstion by mr. Dan Grey as to why time sync is essential. You can find it on the sitech yahoo groups.

2. Reduce the acceleration rate and slew speed from servoconfig in order to minimize slippage. Also allow a delay after slew for settling.

3. Set encoders to polite mode. 

4. Balance the telescope as best as you can. I had a hard time to balance the mesu in every direction, because of the friction drive. There is no precise way to know. But I know for sure an incorrect balance will make a model with poor performance. If there is a way to know how to balance a friction drive precisely please let me know :). 

5. Polar alingn as best as you can

I hope I did not forget any detail. With these tips I made a model with 36 points with a total RMS value of 42 arcseconds. All my targets were near center after the model. I as understand from mr dan G a good model also improves tracking. 

Also the best part is that a 36 point model is built pretty quickly because platesolve 3 engine is really fast. It takes 1-2 seconds per image to platesolve.

Thank you for replying. I guess there aren’t many Skyguard/onag users yet. I nailed down the issues with Skyguard configuration after a long but succesfull discution with mr Gaston B. on cloudynigts forum. If some of you are using Skyguard and Onag maybe our discution will help with setting things up. As a begginer everything has a steep learning curve, but be patient, read the forums, read the manuals and upgrade the software :). I found out that imaging at long FL is challenging for a begginer but not imposible

Following some emails with mr. Lucas Mesu, mr Dan Gray and mr Baudat, 90 % of the problems are resolved. First I had to update the software and firmware of Sitech II (there is no need for additional settings in config.exe or sitech.exe for pulseguide to work). After that the guiding went perfect with Phd2, I was able to grab 15 min exposures of M101 at 2438 mm focal length with ease . The next clear night I will try 20-30 minutes. The remaining issues are with configuring Skyguard to proper autoguide, but we will get there, at leat now I know it's a software issue.

In summary the support was excellent, the mesu 200 mount is excellent

Hey guys, I have a Mesu mount. Are there any settings I need to do in sitech.exe or config.exe in order to  use PulseGuinding?

The reason I ask is I m struggling guiding with ONAG and I wanna make sure the mount is setup properly to use pulseguiding. Anyone using the ONAG with Skyguide or Skyguard?