Skywatcher Motor Drive Dual Axis - Tracking problems

[femalealpha88]

Greetings, I write from Spain and I recently integrated this motor into my EQ5 mount and I have the following problem: - Problems with tracking/monitoring (I'm a newbie)

There are already several tests and this is the "best" that I have obtained by linking the mobile phone to the eyepiece with the Orion nebula.

 

- Problems with tracking/monitoring (I'm a newbie): The motor seems to work correctly but, for example, with a 10mm eyepiece and a lot of magnifications, pointing at the moon, the lens can't stay centered for more than 4 or 5 minutes without having to center again.

The same thing happens with the stars with a 25mm ocular and for example Orion Nebulae, it is less noticeable but they do move a little every 4 or 5 seconds of the frame.

So I can't get exposure times longer than 4 seconds without star trails appearing.

Note: - I don't have many means and I'm quite a novice so I know that this problem may be due to a bad alignment with the polar, in my case Polaris.
Comments would be appreciated suggesting how to correct this problem and achieve longer exposure times and what factors it may be due to other than poor alignment with Polaris.

Thanks in advance.

 

[LaurenceT]

I'm also a relative newbie to all this but looking at the image and doing a search it seems that the item you have is this one:

Motor Drive Celestron | Celestron Motor Dual | Motor Drive Cg-4 | Motor Drive Kit - Astronomical Accessary - Aliexpress

Dual Axis Electric Motor Drive Kit for Celestron CG-4 SkyWatcher EQ3-D EQ3-W | eBay

which doesn't appear to suitable for your EQ5 mount. I also have this mount as a GOTO and it's excellent.

I'm sure somebody with infinitely more knowledge than me will come along soon to help you.

[michael8554]

1. To improve Polar Alignment error you should Drift Align, using a high-power eyepiece that has cross-hairs.

Judge how long to spend doing that by comparing with how much longer you can image for without noticeable elongation of stars !

2.  Almost every mount will have some Periodic Error on the RA axis.

Causing Sidereal Tracking Rate to speed up, and then slow down, in a cyclic pattern.

Over the time it takes the worm to make one turn, often 4 minutes.

Due to machining tolerances in the worm drive.

Nothing you can do to improve your current setup.

Michael

[CraigT82]

That looks to me like the EQ5 Enhanced dual axis drives, but the other drives also linked to above by LaurenceT look the same too, so definitely worth checking you’ve got the right ones for your mount.

Also worth checking the batteries. Low power could cause slow tracking. 

But the first thing to sort is your polar alignment, looking at the pic of M42 the stars seem to be trailing in declination which is a sign your polar alignment is off. Fix that first and then see if it’s still not tracking properly. 

Edited March 5, 2023 by CraigT82

[Cornelius Varley]

32 minutes ago, LaurenceT said:

I'm also a relative newbie to all this but looking at the image and doing a search it seems that the item you have is this one:

Motor Drive Celestron | Celestron Motor Dual | Motor Drive Cg-4 | Motor Drive Kit - Astronomical Accessary - Aliexpress

Dual Axis Electric Motor Drive Kit for Celestron CG-4 SkyWatcher EQ3-D EQ3-W | eBay

which doesn't appear to suitable for your EQ5 mount. I also have this mount as a GOTO and it's excellent.

I'm sure somebody with infinitely more knowledge than me will come along soon to help you.

The mount is an EQ5, the OP has stated that. The motors you linked to are for the Celestron CG4/Skywatcher EQ3-2. The motors in the photo are for the EQ5. The two systems are incompatible, you can't physically attach the EQ5 motors to an EQ3-2/CG4 and visa-versa.

22 minutes ago, CraigT82 said:

That looks to me like the EQ5 Enhanced dual axis drives, but the other drives also linked to above by LaurenceT look the same too, so definitely worth checking you’ve got the right ones for your mount.

Also worth checking the batteries. Low power could cause slow tracking. 

But the first thing to sort is your polar alignment, looking at the pic of M42 the stars seem to be trailing in declination which is a sign your polar alignment is off. Fix that first and then see if it’s still not tracking properly. 

See above. The EQ5 and CG4/EQ3-2 dual axis drives are different.

[LaurenceT]

Yes, I should have been clearer. I shouldn't have said "it seems that the item you have is this one". I'll leave this to the experts.

[CraigT82]

50 minutes ago, Cornelius Varley said:

The mount is an EQ5, the OP has stated that. The motors you linked to are for the Celestron CG4/Skywatcher EQ3-2. The motors in the photo are for the EQ5. The two systems are incompatible, you can't physically attach the EQ5 motors to an EQ3-2/CG4 and visa-versa.

See above. The EQ5 and CG4/EQ3-2 dual axis drives are different.

Yes I know that thanks, that’s why I advised to check they have the right one for the mount. 

[Cornelius Varley]

5 minutes ago, CraigT82 said:

Yes I know that thanks, that’s why I advised to check they have the right one for the mount. 

The motors can't be interchanged between the EQ5 and EQ3-2 mounts. The EQ3-2 RA is attached using a small bracket which is bolted to the side of the mount, the EQ5 RA fits to the underside of the mount and drives through gears, unlike the EQ3-2 which drives the RA directly through a flexible coupling. It would be obvious to the OP that the dual axis drives where not correct for their mount.

[CraigT82]

10 minutes ago, Cornelius Varley said:

The motors can't be interchanged between the EQ5 and EQ3-2 mounts. The EQ3-2 RA is attached using a small bracket which is bolted to the side of the mount, the EQ5 RA fits to the underside of the mount and drives through gears, unlike the EQ3-2 which drives the RA directly through a flexible coupling. It would be obvious to the OP that the dual axis drives where not correct for their mount.

Then that rules out incorrect model for the mount as a potential cause (unless something seriously ham fisted has occurred) 

Looking closer at the posted M42 image the trailed stars do have a zig zag pattern to them suggesting intermittent RA driving perhaps…. Batteries definitely something to check on I think, as well as PA.

[femalealpha88]

3 hours ago, CraigT82 said:

Then that rules out incorrect model for the mount as a potential cause (unless something seriously ham fisted has occurred) 

Looking closer at the posted M42 image the trailed stars do have a zig zag pattern to them suggesting intermittent RA driving perhaps…. Batteries definitely something to check on I think, as well as PA.

Thank you and thank erverybody for your fast responses..

For the ones saying i put an incorrect motor probably the screenshot i chose is wrong or something but the hand controller is the same and the motor is working fine and definitely doing some tracking (if i switch OFF the controller and I'm aiming to the moon then the moon starts to "move" fast and dissapear from my field of view in a few seconds with high magnification, with the controller ON it stops a well centered like a few seconds and at least 6 minutes on the field of view on my ocular before 'dissapearing') --> btw I can re-center the moon using the controller very smoothly and fast on 16x speed.

 

For the stars, definitively is doing some tracking, same as the moon for more time but poor tracking on one axis (RA I suppose). Probably I'll make a fast vid showing it if I don't manage to expain well or my problem persists.

 

- BTW I think the instructions say to put cables for RA and DEC in the wrong order! still have to do some tests.

- The first batteries were for free at the shop but I tried a new ones after noticing the batteries expired on feb 2021 and barely had power to move one or both of the axis.

- Now i'm trying with new batteries and all is working fine, except for the poor tracking.

-------

- Definitely I think is something related to polar aligment, i'm so newbie that I try to do this just pointing de N leg of the tripod the most accurately possibe to Polaris just using my senses not any tool (which I don't have)..

Watched a lot of vids and tutorials trying to learn to do an accurate PA aligment but or i'm a fool (I don't find how to do it manually or I need some digital tools for that.

For example yesterday I can saw Polaris just with my eyes and "aligned" the tripod throwing a green laser beam inside the polar aligment gap and I was pretty close, but I suppose this is not a good method...

 

PS: I read in other thread that I only need to connect the RA axis to do the tracking, is it right?

 

- In any case, some tracking is doing when I switch on the controller, because the star trail is noticeable but not exaggerated when i try to do some short exposure photo (no star trail appreciated at 2 secs, noticeable like in the photo at 4secs exposure.
 
 - Exaggerated Star Trail with the controller with bad batteries or turned OFF.  Just poor tracking when the controller is running with good batteries but did total noob "my way" PA...

- Probably leveling the tripod is determinant too?

 

Sorry for so many questions, I feel so dumb, but for sure I spent lot of hours watching vids, tutorials, talking with the guy of the shop who I bought the stuff... I feel stuck.

Maybe is a good idea buying something like this? (buscador polar.png) :

 

 

Edited March 5, 2023 by femalealpha88

[CraigT82]

20 minutes ago, femalealpha88 said:

Thank you and thank erverybody for your fast responses..

For the ones saying i put an incorrect motor probably the screenshot i chose is wrong or something but the hand controller is the same and the motor is working fine and definitely doing some tracking (if i switch OFF the controller and I'm aiming to the moon then the moon starts to "move" fast and dissapear from my field of view in a few seconds with high magnification, with the controller ON it stops a well centered like a few seconds and at least 6 minutes on the field of view on my ocular before 'dissapearing') --> btw I can re-center the moon using the controller very smoothly and fast on 16x speed.

 

For the stars, definitively is doing some tracking, same as the moon for more time but poor tracking on one axis (RA I suppose). Probably I'll make a fast vid showing it if I don't manage to expain well or my problem persists.

 

- BTW I think the instructions say to put cables for RA and DEC in the wrong order! still have to do some tests.

- The first batteries were for free at the shop but I tried a new ones after noticing the batteries expired on feb 2021 and barely had power to move one of the axis.

- Now i'm trying with new batteries and all is working fine, except for the poor tracking.

-------

- Definitely I think is something related to polar aligment, i'm so newbie that I try to do this just pointing de N leg of the tripod the most accurately possibe to Polaris just using my senses not any tool (which I don't have)..

Watched a lot of vids and tutorials trying to learn to do an accurate PA aligment but or i'm a fool (I don't find how to do it manually or I need some digital tools for that.

For example yesterday I can saw Polaris just with my eyes and "aligned" the tripod throwing a green laser beam inside the polar aligment gap and I was pretty close, but I suppose this is not a good method...

 

PS: I read in other thread that I only need to connect the RA axis to do the tracking, is it right?

 

- In any case, some tracking is doing when I switch on the controller, because the star trail is HUGE when i try to do some short exposure (I got exaggerated Star Trail with the controller with bad batteries or turned off, and just poor tracking when the controller is running with good batteries but total noob PA...

- Probably leveling the tripod is determinant too?

 

Sorry for so many questions, I feel so dumb, but for sure I spent lot of hours watching vids, tutorials, talking with the guy of the shop who I bought the stuff... I feel stuck.

Maybe is a good idea buying something like this? (buscador polar.png) :

 

 

Yea it sounds like you just need to get your polar alignment sorted, a polar scope will definitely help and you can get an app on your phone to tell you where Polaris need to be placed when looking through the polar scope.  The tripod doesn’t need to be level to get a good poor alignment  but it certainly won’t harm it it is levelled.

[femalealpha88]

11 minutes ago, CraigT82 said:

Yea it sounds like you just need to get your polar alignment sorted, a polar scope will definitely help and you can get an app on your phone to tell you where Polaris need to be placed when looking through the polar scope.  The tripod doesn’t need to be level to get a good poor alignment  but it certainly won’t harm it it is levelled.

Thx u so much, i think I'll purchase a polar scope and then keep doing tons of tests. The seller warned me too that the most important is a correct PA and of course hours/days of 'Assay/Error' stuff..

[Cosmic Geoff]

You definitely need a polarscope as without it you will have difficulty getting an adequate polar alignment.  Note there is a limit to what you can expect to achieve with an unguided EQ mount, in terms of exposure length.  It depends on various factors, including the focal length of your imaging scope.

I suspect that a battery powered motorized mount will not be ideal for unguided imaging, but it probably has a guide port, and you could ditch the 6v battery pack and replace it with a mains supply, or a +12v power pack driving a step-down converter (probably sold for R/C model cars and suchlike).

[femalealpha88]

21 minutes ago, Cosmic Geoff said:

You definitely need a polarscope as without it you will have difficulty getting an adequate polar alignment.  Note there is a limit to what you can expect to achieve with an unguided EQ mount, in terms of exposure length.  It depends on various factors, including the focal length of your imaging scope.

I suspect that a battery powered motorized mount will not be ideal for unguided imaging, but it probably has a guide port, and you could ditch the 6v battery pack and replace it with a mains supply, or a +12v power pack driving a step-down converter (probably sold for R/C model cars and suchlike).

Yeah, still don't know how to but it has the port to connect it to a power supply. The seller told me to put 6V. Too noob to test this for myself, I'll look for advice on the shop I bought the mount, telescope, motor etc and also helped me to install the motor. He told me too the most important thing is the adequate polar aligment. 

 

Ordering a polarscope right now!

 

PS: I don't pretend to do exposures longer than 20- 30 seconds... It should be achievable I think..

 

Thank you.

 

 

[Cosmic Geoff]

56 minutes ago, femalealpha88 said:

Yeah, still don't know how to but it has the port to connect it to a power supply. The seller told me to put 6V. Too noob to test this for myself, I'll look for advice on the shop I bought the mount, telescope, motor etc and also helped me to install the motor. He told me too the most important thing is the adequate polar aligment. 

I meant you can use any power source that gives you +6v into the same port that the battery pack connection goes into, so long as it delivers the right voltage with the right polarity.   I used to have a similar setup and I replaced the primary battery pack with a +6v rechargeable battery from Maplin, a home-made lead and a +6v battery charger I bought on ebay.   If in doubt, seek expert advice. 

[femalealpha88]

3 hours ago, Cosmic Geoff said:

I meant you can use any power source that gives you +6v into the same port that the battery pack connection goes into, so long as it delivers the right voltage with the right polarity.   I used to have a similar setup and I replaced the primary battery pack with a +6v rechargeable battery from Maplin, a home-made lead and a +6v battery charger I bought on ebay.   If in doubt, seek expert advice. 

Yeah, i understand but I'm not used to that kind of ports, on my controler. There are 4 ports in controller: 2 for RA and DC, one bigger like the RA and DC axis ports and finally the port that goes from battery pack to controller..  I suppose I only need to attach some rechargeable battery like u said.

If u please can bring me some link to a proper ones witch 6V and DC connector because If i search on Google I'm going crazy...

See what I found:

 

The more I search, the more crazy I am going..

 

Thank you in advance, I'll look for a local advice if I can.

 

If not, the x4 D size batteries at 1.5V each are fine by the moment. I found a lot of 6V on alliexpress but I'd preffer to buy somewhere else. Rest are 5-5.2V powerbanks with DC adaptors or ~7.xV and I don't want to burn the stuff or something.
 

[michael8554]

"learn to do an accurate PA aligment ......... don't find how to do it manually"

As I said:

1. To improve Polar Alignment error you should Drift Align, using a high-power eyepiece that has cross-hairs.

This is a manual adjustment.

But you may find that just the Polar Scope is accurate enough for the length of exposures you want to use.

1. First, aim the mount's polar axis roughly at Polaris. Now point the telescope at a star that's somewhat above the celestial equator and as close to south as you can judge by looking opposite Polaris. Put in a high-power eyepiece. If the eyepiece has cross hairs, center the star on them. Otherwise put the star on the north or south edge of the field and defocus it a little. Turn on the clock drive, and ignore any east-west drift.
2. If the star drifts south in the eyepiece, the polar axis is pointing too far east.
3. If the star drifts north, the polar axis is too far west.
4. Shift the polar axis left or right accordingly, until there is no more drift.
5. Now aim at a star that's near the celestial equator low in the eastern sky.
6. If the star drifts south, the polar axis points too low.
7. If the star drifts north, the polar axis points too high.
8. Again, shift the polar axis accordingly.
9. Now go back and repeat from the beginning, because each adjustment throws the previous one slightly off. When all visible drift is eliminated the telescope is very accurately aligned, and you can take long deep-sky exposures. If your eastern sky is blocked, you can use a star low in the west and reverse the words "too high" and "too low" in the above instructions. If you're in the Earth's Southern Hemisphere, reverse the words "north" and "south."

Step 4 means rotate the mount's body horizontally a tiny amount, 

Step 8 means alter the "tilt" of the mount's body a tiny amount.

Michael

 

[Cosmic Geoff]

12 hours ago, femalealpha88 said:

Yeah, i understand but I'm not used to that kind of ports, on my controler. There are 4 ports in controller: 2 for RA and DC, one bigger like the RA and DC axis ports and finally the port that goes from battery pack to controller..  I suppose I only need to attach some rechargeable battery like u said.

I assume the single larger port is for guiding.

12 hours ago, femalealpha88 said:

If u please can bring me some link to a proper ones witch 6V and DC connector because If i search on Google I'm going crazy...

Nearly all the found options will require some soldering etc for making up leads. If you are not used to connecting up electronic stuff, it would be safer to confine your attention to power sources that will plug into the small round port as-is.   You need to confirm that the plug size and polarity match up to the original.

Is a small mains-powered PSU an option?