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Plate solving fails in SGP

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#1 DougSol

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Posted 03 December 2019 - 11:13 AM

I recently changed out my setup from a 127mm ES refractor to a 200mm RC, with reducer bringing it to F5, and still using an OAG. I'm also still using a CGX mount. with the CPWI software. I also replaced my computer hard drive and went from Windows 7 to Windows 10. I of course also reinstalled SGP on the new hard drive and created a new equipment profile. When SGP tries to plate solve the mount gets to within about 180-200 pixels and then keeps over correcting back and forth in the RA axis. The dec gets quite close. I have the plate solve tolerance set at 50 pixels. It worked fine before I switched everything, but now it fails every time! Any help would be very much appreciated.

Doug



#2 ChrisWhite

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Posted 03 December 2019 - 11:40 AM

Did you change the pixel scale in SGP?
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#3 DougSol

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Posted 04 December 2019 - 12:27 PM

Thanks for responding! Yes I did. I got .46" per pixel... F8 8 inch RC = 1600 x .67 reducer=1072 f.l. with 2.4 micron pixels(183M ZWO camera). I think I got it right?

Doug



#4 artem2

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Posted 04 December 2019 - 12:59 PM

Hello Doug,

 

In SGP you need to setup or actually create a PROFILE for your FOV. and then setup the data as below in SGP.

 

See the 2 screen shots below.. and then chose a plate solver and then solving should work..

 

Cheers

 

Martin

Attached Thumbnails

  • 1.PNG
  • 2.PNG

Edited by artem2, 04 December 2019 - 01:00 PM.


#5 Stelios

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Posted 04 December 2019 - 01:15 PM

Hello Doug,

 

In SGP you need to setup or actually create a PROFILE for your FOV. and then setup the data as below in SGP.

 

See the 2 screen shots below.. and then chose a plate solver and then solving should work..

 

Cheers

 

Martin

Also... when you create such a profile, if you will use an existing sequence, remember to apply the profile to sequence first. 

 

Alternatively, you could set up as above using the control panel in an existing sequence (more work that way though).



#6 Alex McConahay

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Posted 04 December 2019 - 05:58 PM

Don't mean to be pedantic, I don't think your plate solver is failing. It seems your centering is failing. 

 

Why is this not pedantry? Because from your description, you seem to have situation where your plate solver delivers a solution. That is, it analyzes a picture, and tells the computer (and you) where the scope is pointed. This is plate solving. And, it seems like yours is doing that. 

 

All the suggestions so far are about how to get your computer to properly determine, with Plate Solving, where you are pointed. I think that part is already taken care of.

 

What it is not doing is correcting the pointing accurately. This I get from:

 

" When SGP tries to plate solve the mount gets to within about 180-200 pixels and then keeps over correcting back and forth in the RA axis." If it knows it is 180-200 pixels off, it must have a successful plate solve.

 

By the way....after the solve, SGP knows what the actual plate scale is, regardless of what you entered into the configuration. 

 

So, I doubt plate scale, focal length, and all that is important. That stuff is important to the original solve.  But you have that.   

 

Now, does that stuff contribute to telling the mount how much to move? I don't think so, but may be wrong. 

 

I think it more likely the problem is someplace in the RA drive. It could well be mechanical. How is the backlash? Balance? How tight is the worm mesh? Is the offset of 180-200 pixels always in the same direction? How well does goto work independent of SGP?

 

Alex


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#7 DougSol

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Posted 04 December 2019 - 06:42 PM

Thanks for the replies,

I don't think there is a mechanical problem, since the plate solving worked fine until I changed the scope  and hard drive and reinstalled SGP. Scope is balanced and no lighter than the previous scope. Could the binning setting screw things up? It was 2x2. I just changed it to 1x1 and will try it when the weather clears. I'll check the telescope profile, as well. Goto is working pretty well. The indicated large error is consistently in the RA.



#8 Madratter

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Posted 04 December 2019 - 07:06 PM

Again, to echo Alex, it does not sound like a platesolving problem. It sounds like a centering problem. If the platesolving was failing, then the mount would not try to move.

 

For centering to work properly, either you need to allow the mount to sync OR you need to use one of the alternative methods that will try to move the mount a given distance from where it is.

 

Those settings are here under Sync Behavior:

SyncBehavior.PNG

 

If your mount syncs properly (probably a setting of the mount allows or turns sync off) then the sync setting is appropriate. If it doesn't, you can chose an alternative method like "Target Offset".

 

Personally, with my mount I have to use Target Offset to avoid the sync screwing up my sky model.



#9 Alex McConahay

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Posted 04 December 2019 - 07:18 PM

Are you syncing the scope after a plate solve?

 

ALex



#10 DougSol

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Posted 04 December 2019 - 08:51 PM

No. I haven't. I'll have to check the sync behavior setting.




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