Jump to content

740427863_Terminatorchallenge.jpg.2f4cb93182b2ce715fac5aa75b0503c8.jpg

Alignment problems


Recommended Posts

Hi, can someone help with alignment problems,  I have a Skywatcher skymax 127 on an EQ3 goto mount but it will not align on stars.  I know I am inputting the correct co-ordinates along with all the other info.  When it does star alignment it is always out by a considerable amount which I correct but then it has the same error on the next star or if only doing 1 star alignment its not in alignment with the next target.  I have had it working ok some months ago, but then it went out of sync so I started the alignment from the beginning, even using the computer with Stellarium it does not goto the target selected.

Link to comment
Share on other sites

When you say it was working some months ago, was this before daylight saving time? Have you adjusted for Summertime? Sorry I don't know what BST is called in Bulgaria! 

Link to comment
Share on other sites

Thanks for the reply, I actually can't remember if it was during the summertime, UK BST ,  Bg EEST.  When entering time zone in setup, does it require GMT or BST.  GMT is +2 hrs but in Summertime it is +3, but the control asks if its daylight saving.  I have tried both but the error still persists.  I have also tried setting Polaris on the clock face differently, as my clock face zero does not point to 12.  I seem to recall that everything worked ok before I upgraded the hand control to the latest software version.  Some posts suggest a power problem, but I use a mains PSU which has stabilized voltage adjustable up to 15v with 10A current capacity.  I am close to my wits end but will try a car battery on the mount just in case.  A point I have discovered is, I used my mobile phone app Align Pro to do a daytime setup and have since discovered my phone is giving wrong Lat/Long, however I have since done a correction with a night time setup.  This is infuriating as I can't use the mount Goto function as I have to keep correcting it manually for bright known objects and can't find deep sky objects at all.

Link to comment
Share on other sites

One common error is inputting the day as the month and the other way round. Worth checking that. The American format is month-day, the European day-month.

Also check your tracking rate. You should be set to the sidereal rate.

You can check your polar alignment easily enough without go to. This might be worth doing. Polar align, set the mount's tracking in motion at sidereal rate then move manually to centre a bright star, ideally close to the celestial equator in the south but certainly a long way from Polaris. Then just watch how quickly the star drifts out of view on a low power. It should take some time. If it drifts quickly then your polar alignment or tracking speed must be faulty.

Olly

Link to comment
Share on other sites

Unless you explain in some detail what exactly you do or did to align, so we can spot your error, it may be difficult for us to do more than make random suggestions.

One thing I found out is that accurate polar alignment is not necessary for an equatorial GoTo to work properly for visual observing.  The precise polar alignment is only required for imaging (to prevent field rotation).  If you are still not convinced, I will point out that alt-azimuth mounts manage the same task just fine without any polar alignment at all.

Newbies are often confused by the design concept of the Synscan software - you are meant to use a 'start position' so that the mount can slew to the approximate location of an alignment star before you have carried out the GoTo alignment.

Another thing I found out is that the mount can GoTo accurately on one side of the sky but allow it to do a 'meridian flip' and it is out of alignment on that other side of the sky...

  • Like 1
Link to comment
Share on other sites

10 hours ago, DDH said:

... I seem to recall that everything worked ok before I upgraded the hand control to the latest software version ...

Perhaps a daft question, but I assume you upgraded to the latest version of software applicable to the version of hand controller that you have (V3 or V4/5)?

Link to comment
Share on other sites

This seems very similar to a problem raised last week where the poster said the co-ordinates were wrong. He had updated the firmware. What seemed to fix his problem was to flip the DST setting from Y to No and back again and do a power cycle.

See the thread here

Worth a  try I think as it's so similar.

  • Like 2
Link to comment
Share on other sites

Thank you very much for all the replies I will look at all of your advice .  Last night I tried to set the system up again, so will run through what I did to setup.

Level the mount in both RA and Dec and check its pointing North.  Turn on Synscan and delete PAE then did a factory reset. ( I assume at this point all previous settings should have gone).  I checked NPE and it showed a value of 0.  Check PSU voltage  Reading on handset 13.5v.  Shut down Synscan at Home.  Restart, enter location E 24.56  N 42.49 enter,  time zone +02.00 enter, now the strange one, the system remembered the elevation setting from previous. ( I thought it should have deleted all previous info).  elevation  +352 enter, date 07/26/2021 enter, time 22:04 enter,  daylight saving yes enter, Polaris pos. set HH MM on center circle at time shown on handset, ( must remember to make a log of this) enter, start alignment, 2 star,  Arcturus, mount stopped high to left, center star enter, align success, 2nd star Dubhe enter,  Now the same happens the mount stops high to left, center star enter, align success,  ESC enter, select object list enter,  from this point on all objects selected the mount stops high to the left.  All of the final positions were exactly the same amount out of alignment and I had to re center.  The strange thing is previously before the handset upgrade the mount did work perfectly with all the same settings as above and was very accurate and did track objects very good.  One point to note though, was that the scope would never locate Polaris when I selected Star object, the mount would stop high above as though the scope was not aligned with the polar scope, another point I noticed last night was on my 2nd attempt to setup, Polaris did not appear on the clock, it was to the right of 12 above the circles?  This was probably due to the fact that I had to switch off while the mount was moving to another star as it was moving below the horizon and the scope was about to collide with the tripod!.  Sorry for the long post and I will look at all your suggestions today.

Link to comment
Share on other sites

On 27/07/2021 at 04:16, DDH said:

start alignment, 2 star,  Arcturus, mount stopped high to left, center star enter, align success,

I would have thought the "align success" message would come after the second alignment star in a 2 star alignment, not after the first ?

Michael

  • Like 1
Link to comment
Share on other sites

Posted (edited)

Yes I am centering with the controller and it has the same error on any star selected ( and my manual states that after 1st star it does say alignment success.) not just stars, any item selected from the handset menu after the alignment procedure.  I know from when I first got the setup , when I did a 2 star align after centering the first star the second was always right on and didn't need alteration with the handset.  Now it does not matter how many stars I use as alignment they are all out by the same amount.  Yesterday I discovered that my polar reticle was out of alignment which I corrected by taking the rig outside in the daylight.  So last night I did a new polar alignment which was well centered but I still got the same results after star alignment.  I have also tried to make sure the scope is inline with the polar scope, but still the same result, oh, and yes I did ensure that the mount was level and pointing north after the move in the day.  Last night I did record the location of the alignment stars , what location info the hand control gave and the final location result given by the hand control so will publish this info later in case it has some bearing.  One other point I noticed last night is the tracking is not good, I made sure the mode was set for sidereal rate.  Also in my manual it gives an option to stop tracking, I do not have this option.  Thanks for the replies, much appreciated.

regards David

Edited by DDH
Link to comment
Share on other sites

On 27/07/2021 at 04:16, DDH said:

Arcturus, mount stopped high to left, center star enter, align success, 2nd star Dubhe enter,  Now the same happens the mount stops high to left, center star enter, align success,

Are you saying its consistently off by a similar amount? Can you explain a bit more about high to left please? I am trying to visualise where is the star and where is the mount. Is the star in the field of view and just not centered in the eyepiece or is it way off.

Even a simple drawing on paper would help

Edited by AstroMuni
Link to comment
Share on other sites

This may not help but always finish with right and up keys this will help with backlash. 

My EQ5 does this regularly and with other objects I suspect on the other side of the sky they are bottom and right in the FOV, other times it hits every target very near dead centre and I do the same set up every time. 

1. Tripod out and level using a level. 

2  Mount on check level again. 

3 polar align using polar align Pro. 

4.weights on and scope check polar scope tweak if necessary. 

5  Pick a bright star in the sky align on that see what handset gives me go to that star Close but not that close. 

6.once aligned I always go to a known object now this is where I have problems it's either bang on or up and left or bottom and right so I will either go to next object or press escape then press escape but hold down until it flashes up to centre object do that press enter. 

7.Try a new known object see how that is but like you no matter what I do it stays up and left or bottom and right. 

I have no idea why these mounts are so fickle. 

Link to comment
Share on other sites

How tight are your clutches? under the clutches are sliding surfaces that are lubricated and if you dont tighten them enough you could have slipping.

That would lead to the motors running to the target but the actual movement is less because of slipping.

If you can easily move the scope by hand when the clutches are locked, so can the motors. 

  • Like 1
Link to comment
Share on other sites

3 hours ago, ONIKKINEN said:

How tight are your clutches? under the clutches are sliding surfaces that are lubricated and if you dont tighten them enough you could have slipping.

That would lead to the motors running to the target but the actual movement is less because of slipping.

If you can easily move the scope by hand when the clutches are locked, so can the motors. 

I wondered about slippage too.  The mount and Stellarium think they've gone to the correct position so the pulse counts are correct but the mount is pointing at the wrong place.  If all the data entry is correct and PA is ok then that would suggest slippage. Is the scope well balanced?  I wondered if it was badly out of balance that might cause slippage.  I have an HEQ5. I don't need to align any longer but I used to find that doing a 3 star alignment from the home position the first star was quite a way off, the second star was closer but still off but the third star was usually quite good but not brilliant. In the eye piece at least. I usually put down the error to flexure and think that was confirmed because after a meridian flip the alignment was off again.

I guess you are using your scope visually - i.e. no camera.

 

Link to comment
Share on other sites

Posted (edited)

ok so the setup is all correct on level etc. Wookie1965, my mount sounds exactly the same as yours, all targets appear in the finder up and left.   I did find out yesterday that there is a software update for the mount so I did the update, I also checked the motor control software and don't know how relevant this is but my version is 2.7.03 but on the Skywatcher site it should be 2.7 no.03 so could this be a problem?  My thoughts are the step instructions to the motors.  I did download 2.7 but I can't install as my hand control returns the message "update failed file already open! "  I have contacted Skywatcher about this.  One more point about the alignment errors, I can see the star selected in the finder but not in the scope with a 40mm eyepiece, another problem is that if the finder has been knocked or moved then it is very difficult to align the scope.  Another annoying point and I don't know if its common is that when selecting a star for alignment the handset only gives me about 6 star selection then keeps repeating the same and if they can't be seen, can be a problem.  Some of the alignment stars are not the brightest and my eyesight is not great, but the handset won't give me a choice for the brightest stars.  To sum up, I now have no confidence in Skywatcher equipment as I have also had a few problems with my Explorer 190MN

Edited by DDH
Link to comment
Share on other sites

If you suspect the mount is missing counts, or has some motor control problem, you could test this - do a fake daytime alignment procedure (1 or 2 star, doesn't matter ) then point the telescope at a terrestrial object that isn't going to move. Read the axis position ( utility menu I think). Make sure you are reading the actual axis position , labelled AX1 and AX2, not RA and DEC. One of the axes will be changing a little bit because of tracking, but note the position of your axes as best you can.

Next move the scope around a bit, do a  few fake GOTOs, then return to point at your original terrestrial object. 

Read the axis position again. Is it the same as the first reading?

If different then you have found the problem. If it's the same, the the problem is something else. Let us know what you find ...

 

 

 

Link to comment
Share on other sites

... If the positioning system is ok, the next step is to check the demanded position is correct .

Do a 1 star alignment on Arcturus, but do not move the scope yourself, don't try to centre the star in the eyepiece, just press enter at the initial slew position.

Now read the alt/ az ( not Ra/Dec) position from the utility menu.

Compare with the alt/az position of Arcturus from an independent source for your time and location ( stellarium, cartes du ceil, compass and sextant). Same or different? If different then look again carefully at the initial data for location etc. you enter into the handset. 

  • Like 1
Link to comment
Share on other sites

  • 2 weeks later...

Sorry just seen your post today, Mutley.  So I have not tried your first suggestion but have tried the second and my results are not consistent.  for Jupiter the handset reads 221° 41 +24° 08.    mount stops at 221° 51. +24° 04.  when in center of view 222° 08  +23° 54. For Moon handset reads 119° 42. +46° 29. Mount stops at 120° 09. +46°  44. when in center of view 120° 44. +47° 05.  Then later the moon is 135° 45. +54° 19. mount stops at 136°03. +54°26. when in center of view 136° 27. +54° 34.    Sometimes the mount will stop with the object in view on the OTA but other times its not visible only in the finder.  The other thing is I use Stellarium sometimes to locate objects and on comparing the above info with the software I don't get the same readings as on the handset although if I use Stellarium to view the object it always centers on it, but is not visible in the OTA, maybe in the finder.  The location co-ordinates are the same on both except that you can only enter 4 digits in the handset.  Since doing this experiment I have moved the mount and checked levels, mounted scope and checked levels again, checked pointing North,  entered all the correct info in the handset and done a polar check and set the reticle correct, then 2 star align, first star almost in center, 2nd star visible in finder but not in OTA.  Handset records alignment success but gives the previous version of NP is applied.  On checking NPE the reading is 0°.00.01. After this all targets selected from the handset or Stellarium are way off, not visible in OTA but maybe visible in finder. 

Regards David

Link to comment
Share on other sites

Ok, so a lot of stuff there. Here's my thoughts:

On 10/08/2021 at 08:31, DDH said:

my results are not consistent.  

Try the terrestrial test ( my first post)to determine if the positioning system is accurate an repeatable.

On 10/08/2021 at 08:31, DDH said:

Jupiter the handset reads 221° 41 +24° 08.    mount stops at 221° 51. +24° 04.  when in center of view 222° 08  +23° 54.

That's only about half a degree of error if I'm reading you right. You might get that from a sub-optimal alignment procedure.  Are you following the manual i.e. finishing the star alignment with movement on the UP and RIGHT arrow keys to eliminate backlash error? Are you aligning using the eyepiece or the finder scope? Does your alignment eyepiece have cross hairs? What is the field of view/magnification of your eyepiece?

Also, I have a feeling from using it that SyncScan is less accurate on solar system objects than on fixed stars and DSOs. Could you try testing on a bright star instead of Jupiter?

On 10/08/2021 at 08:31, DDH said:

Handset records alignment success but gives the previous version of NP is applied.

I would make sure values stored for NPE and CE ( cone error) are both set to zero - just to eliminate them.

Best of luck,

Mut

Link to comment
Share on other sites

Thanks Mutley,  Iv'e been away for a few days break and just got back today.  I will try all of your suggestions and report back, just to say about NPE and cone error I regularly delete them and Yes, I follow the manual, Up and right.  I don't have a cross hair eyepiece but have a previous suggestion to use  a large mag eyepiece and de focus the star to fill the eyepiece, which seems to center the star quite well, previously I used a 40mm plossl.  Once again many thanks for the help

 

Regards David

Link to comment
Share on other sites

Hi, Many thanks to all that tried to help with this problem.  Today I discovered the cause for the non alignment issue, it would appear that the EQ3 pro Goto mount has a manufacturing fault on the DEC axis and as the unit is less than 1 year old, the supplier has asked for it to be returned to them.  Basically as the DEC axis rotates, the OTA's altitude goes out of alignment.  This was discovered by removing the OTA and fitting a spirit level in its place and operating the mount. 

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share

  • Recently Browsing   0 members

    • No registered users viewing this page.
×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue. By using this site, you agree to our Terms of Use.