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Polar Aligning with Celestron Nexstar 6se plus a Wedge

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#26 lo12310

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Posted 22 July 2019 - 12:24 PM

This diagram is correct for a Starsense ASPA in the Northern Hemisphere. The lean is dictated by your Latitude setting on the wedge. But as I said before, during this set up, try to get your OTA closely aligned along an imaginary line through N-S. Use a compass. A degree or two off this imaginary line will increase your Polar Alignment Error (PAE) and mean more wedge turns are required. Repeating the ASPA might be necessary for convergence to minimise PAE.

 

What confuses everybody are the diagrams in the Nextar and CPC  instruction manuals that show a set up whereby the OTA initially points towards Polaris. That predates ASPA procedures. It's time Celestron

I tried starsense ASPA but with a different orientation than the one above. That explains why the polar alignment was so off that i had to literally move the tripod to get the telescope polar aligned correctly.



#27 Noah4x4

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Posted 22 July 2019 - 12:31 PM

I tried starsense ASPA but with a different orientation than the one above. That explains why the polar alignment was so off that i had to literally move the tripod to get the telescope polar aligned correctly.

For a regular Starsense auto-align you can select any Horizon. But for a Starsense ASPA your OTA must point South at the celestial equator. Hence, as per the diagram.



#28 lo12310

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Posted 24 July 2019 - 11:03 AM

Update: So i hooked up the starsense last night and i was happy with the results. I did a starsense autoalign and than a polar alignment and than another starsense auto align. The goto was very precise. I have to say there is still star trailing in my 1 minute exposures so should i just keep doing polar alignments and autoaligns until theres no more star trailing? Also my cable managment is garbage between the SSA cable and the telescope power cable which might pull on the mount slightly.



#29 Biofish

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Posted 25 July 2019 - 12:42 PM

From my book, The NexStar User's Guide II:

 

All-Star Polar Alignment (sometimes referred to as ASPA) is Celestron’s marketing

name for a wedge alignment routine that allows you to use almost any bright star

as a reference point. This name is found in the some of the newest manuals but not

in the hand control menu.

 

Polar Alignment with the NexStar+ Hand Control
 

Procedure
 

So i followed the above guidelines for the ASPA steps.. still didn't track very well and goto was off. I did it over and over again with similar results. I started wondering:

1) Is it correct that the "Tracking mode" needs to be set to "North EQ" every time you power up the hand controller? Is it not saved even when you power off?

2) If that is true, is there somewhere in the settings to tell the scope that you are using a wedge?

I hope this was my issue



#30 lo12310

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Posted 25 July 2019 - 04:11 PM

So i followed the above guidelines for the ASPA steps.. still didn't track very well and goto was off. I did it over and over again with similar results. I started wondering:

1) Is it correct that the "Tracking mode" needs to be set to "North EQ" every time you power up the hand controller? Is it not saved even when you power off?

2) If that is true, is there somewhere in the settings to tell the scope that you are using a wedge?

I hope this was my issue

I had this same issue. I put in the exact coordinates for location instead of using database and had better goto results but my polar alignment is still garbage. I would purchase a starsense autoalign. It's pricey but you get your money's worth. I don't think there's a setting for wedge with the original hand control. The hc that comes with the SSA has a wedge setting though. Clear skies.


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#31 Michael_Swanson

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Posted 25 July 2019 - 11:54 PM

So i followed the above guidelines for the ASPA steps.. still didn't track very well and goto was off. I did it over and over again with similar results. I started wondering:

1) Is it correct that the "Tracking mode" needs to be set to "North EQ" every time you power up the hand controller? Is it not saved even when you power off?

2) If that is true, is there somewhere in the settings to tell the scope that you are using a wedge?

I hope this was my issue

On the NexStar/NexStar+ hand control (HC), after performing any of the EQ North/South alignments, the HC automatically sets the tracking mode to EQ North or South as appropriate.  Selecting EQ North/South alignment tells the NexStar/NexStar+ HC you are using a wedge.

 

The StarSense HC has a setting to tell the scope you are using a wedge since it automates the entire alignment process (you don't specify alt-az or EQ when you start the alignment) and so it needs to know you are on a wedge in advance so it doesn't end up pointing at the ground capturing images of grass.

 

Some questions:

  • Are you using a true wedge with smooth azimuth and latitude adjustments? 
  • Was it easy for you to center the polar alignment star in the eyepiece during ASPA during the set for adjusting the wedge? 
  • Which particular EQ alignment routine are you using: EQ AutoAlign, EQ TwoStarAlign, etc.? 
  • Was that procedure easy for you? 
  • Are you finishing centering of the alignment stars in the eyepiece with the RIGHT and UP arrow buttons? (assuming the GoTo Approach is set to POSITIVE for AZM and NEGATIVE for ALT - the defaults for a NexStar+ HC) 
  • What two alignment stars did you use this last time?

 

Best regards,
Mike Swanson
Author of "The NexStar Users Guide II"
Author of "The NexStar Users Guide"
Author of "NexStar Observer List"
https://www.nexstarsite.com


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#32 lo12310

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Posted 26 July 2019 - 12:28 AM

I had another session and i wasnt happy. I performed a starsense autoalign and then did a polar alignment for altair and nunki. Even after doing this over again like 6 times, my 1 minute exposures still have star trailing. What would be the best star to use for the all star polar alignment? Are my expectations for the wedge too high?



#33 Biofish

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Posted 26 July 2019 - 12:45 AM

 

Some questions:

  • Are you using a true wedge with smooth azimuth and latitude adjustments? 
  • Was it easy for you to center the polar alignment star in the eyepiece during ASPA during the set for adjusting the wedge? 
  • Which particular EQ alignment routine are you using: EQ AutoAlign, EQ TwoStarAlign, etc.? 
  • Was that procedure easy for you? 
  • Are you finishing centering of the alignment stars in the eyepiece with the RIGHT and UP arrow buttons? (assuming the GoTo Approach is set to POSITIVE for AZM and NEGATIVE for ALT - the defaults for a NexStar+ HC) 
  • What two alignment stars did you use this last time?

 

 

Thank you for being willing to assist me. Let me give you the details of the process I am using:  I would not say it is easy, compared to the ease at which I had auto-aligned without a wedge in the past.

 

 

I have the Nexstar + HC with the most recent update
I have the Celestron wedge for the 6/8 se
I have set the Latitude adjustment on the wedge to 35 degrees, due to my location in Chattanooga, Tn
I have leveled the tripod

-I begin by using a compass to determine North and point the base of the wedge and the forkarm roughly in that direction (to the best of my ability)
-I line up the optical tube facing the other direction (South) and make sure the index arrows are pointing to each other
-I turn on the HC and select "Align" and then select "EQ North"

-I enter the time/date and then select "EQ Auto Align"

-It asks me to confirm the Index marks, which I already did, so i press enter
-It asks me to confirm that the tube is pointed at the Meridian, since I have pointed the mount north and have the forkarm vertically on one side (like the picture above) I assume it is pointing at the Meridian (Possibly my issue?)
-It asks me to "Select star 1" - I chose Deneb. It slews close..but i use the arrows to adjust. Hit enter, then Align when perfect with my 12mm illuminated reticle.
-It asks me to "Select star 2" - I chose Antares. It slews but is off by more than Deneb, still kinda close. I use the arrows to adjust. Hit enter, then Align when perfect with my 12mm illuminated reticle.
-It tells me alignment was successful.
-I then goto "Stars" and select Antares. It slews away and then back.
-I then select "Align" and then "Polar Align" and then "Align Mount"
-The mount slews to Antares again. I center the star and it syncs.
-It then continues the polar alignment process and slews away from Antares a bit. (about 10 degrees)
-To center Antares, I have to use the Az adjustment knobs AND the Latitude adjustment knob. I notice that the LAT degrees are now at 38 displayed on the side of the wedge. Where I live it should be 35.
-I undo the sync.
-I tell the mount to GOTO Jupiter. It gets close, but i have to adjust it as it is not in the field of view. (1-2 degrees off)
-If i place Jupiter in the middle of my 12mm eyepiece, it will be gone within 10-20 minutes, so it is not tracking correctly.


I hope I answered all your questions. Don't hesitate to call me an idiot.!   I do love to learn though...

 



#34 Michael_Swanson

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Posted 26 July 2019 - 01:07 AM

After you complete your final alignment, press the Align button and check the polar alignment error to get an idea how well ASPA worked for you.

 

Also note that the SE mount has spur gears which are not by any means precise.  

 

Best regards,
Mike Swanson
Author of "The NexStar Users Guide II"
Author of "The NexStar Users Guide"
Author of "NexStar Observer List"
https://www.nexstarsite.com



#35 Biofish

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Posted 26 July 2019 - 01:10 AM

I will do that tomorrow night and check it.No issues with my process though? I was hoping I made a rookie mistake.

#36 Michael_Swanson

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Posted 26 July 2019 - 01:32 AM

Just a couple of notes for your next attempt:

  • The meridian is the line running from south on the horizon, directly overhead and then down to north on the horizon.  Since the scope comes close to the first Auto Align star, I think you have that correct.
  • After you complete the Polar Align, I would recommend powering off, powering back up and performing another clean alignment.  
  • Please do pay attention to the final motions when centering the alignment stars in the eyepiece.  As I noted above, if the GoTo Approach is set to the default of AZM positive and ALT negative, you must center the alignment stars with the RIGHT and UP arrow buttons.  If you overshoot, you must back up and still approach center with RIGHT and UP.

After that, check the reported polar alignment error (sometimes abbreviated PAE).

 

As far as the latitude adjustment needing to be 38 vice 35:  First, if the tripod is unlevel, you can expect this (and 3 degrees isn't much).  Second, that scale isn't known to be highly accurate.

 

Best regards,
Mike Swanson
Author of "The NexStar Users Guide II"
Author of "The NexStar Users Guide"
Author of "NexStar Observer List"
https://www.nexstarsite.com


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#37 Biofish

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Posted 27 July 2019 - 01:40 AM

Just a couple of notes for your next attempt:

  • The meridian is the line running from south on the horizon, directly overhead and then down to north on the horizon.  Since the scope comes close to the first Auto Align star, I think you have that correct.
  • After you complete the Polar Align, I would recommend powering off, powering back up and performing another clean alignment.  
  • Please do pay attention to the final motions when centering the alignment stars in the eyepiece.  As I noted above, if the GoTo Approach is set to the default of AZM positive and ALT negative, you must center the alignment stars with the RIGHT and UP arrow buttons.  If you overshoot, you must back up and still approach center with RIGHT and UP.

After that, check the reported polar alignment error (sometimes abbreviated PAE).

 

 

 

 

Better results tonight.   North EQ aligned, polar aligned making sure i finalized the centering with UP and RIGHT directions. Turned off the HC and then did a North EQ align again. Checked the PAE. This is what it showed:

After a few attempts, i noticed that it was more accurate with just the N EQ align than when I added the Polar align. In short, the Polar align is making it worse.

 

gallery_311305_11585_1663589.jpg


#38 lo12310

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Posted 27 July 2019 - 11:37 PM

To be honest it would be nice if they made a polar scope for the wedge



#39 Michael_Swanson

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Posted 29 July 2019 - 01:00 AM

 

Better results tonight.   North EQ aligned, polar aligned making sure i finalized the centering with UP and RIGHT directions. Turned off the HC and then did a North EQ align again. Checked the PAE. This is what it showed:

After a few attempts, i noticed that it was more accurate with just the N EQ align than when I added the Polar align. In short, the Polar align is making it worse.

 

That's very unusual.  Maybe try a different star for the polar alignment which is NOT one of your EQ Align stars.

 

 

Best regards,
Mike Swanson
Author of "The NexStar User's Guide II"
Author of "The NexStar User's Guide"
Author of "NexStar Observer List"
https://www.NexStarSite.com



#40 lo12310

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Posted 01 August 2019 - 12:39 AM

I'm starting to think my polar alignments are not the problem. I got the error down to 35" on both axis'. I took 40" x 100 shots of the dumbbell neb and when i looked back at the pictures, i noticed that it would shift back and forth a little along with the majority of shots containing star trailing. Is my ra motor messed up or do i need to change a setting on my telescope so the tracking is smoother. (Note: this is celestron 6se with wedge)


Edited by lo12310, 01 August 2019 - 12:55 AM.


#41 Michael_Swanson

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Posted 01 August 2019 - 01:00 AM

I'll go with my earlier post:

"Also note that the SE mount has spur gears which are not by any means precise."

 

And add that the motors are not that precise either. 

 

I would think fewer slightly longer exposures rather than attempting to stack 100 forty second shots would be better for this setup.  Although your stacking software should be able to deal with the drift successfully.  

 

Bottom line - with an understanding you won't get perfect tracking from this mount and then experimenting a bit, I think you will get results you are happy with.

 

Best regards,
Mike Swanson
Author of "The NexStar Users Guide II"
Author of "The NexStar Users Guide"
Author of "NexStar Observer List"
https://www.nexstarsite.com



#42 Biofish

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Posted 01 August 2019 - 01:15 AM

I have a starsense coming tomorrow we'll see if that will help with alignment. However I am saving for a good EQ mount. I would love to get the heq5 however I don't think I can afford one anytime soon. Are the ioptron goto EQ mounts decent? They seem to be less expensive but I don't want to buy crap anymore.

#43 lo12310

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Posted 01 August 2019 - 04:49 PM

I'll go with my earlier post:

"Also note that the SE mount has spur gears which are not by any means precise."

 

And add that the motors are not that precise either. 

 

I would think fewer slightly longer exposures rather than attempting to stack 100 forty second shots would be better for this setup.  Although your stacking software should be able to deal with the drift successfully.  

 

Bottom line - with an understanding you won't get perfect tracking from this mount and then experimenting a bit, I think you will get results you are happy with.

 

Best regards,
Mike Swanson

Dumbbell Nebula Redone

Author of "The NexStar Users Guide II"
Author of "The NexStar Users Guide"
Author of "NexStar Observer List"
https://www.nexstarsite.com

Thanks for the info. And yes it's a bitter sweet situation but i was still able to get 37 of the 100 shots from the night before. In the future i do plan on purchasing a gem mount. 

 

Dumbbell Nebula Redone



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