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Meridian Flip Framing Question

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#1 Tecc77

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Posted 17 October 2021 - 09:05 AM

Imagine this scenario…

You setup on the Andromeda Galaxy in the early evening with plans to image through the night using NINA. You’ve setup the framing so that the center of the Galaxy is center of your core image. Sometime later, after the auto meridian flip, you notice the image is in focus, but is no longer centered. It’s as much as an inch off from the center of your original framed center.

In NINA I have plate solving turned on, and I have imported the target coordinates from Stellarium before starting the sequence.

Is my meridian flip alignment a function of poor polar alignment, poor star alignment, both. Something else?
I used SharpCap to polar align down to the excellent range (20” in error). I have a 6 point star alignment model using CPWI.

I paused the sequence, reframed my image an resumed. It’s just not as automatic as I would like, and I’d like to be better.

Thoughts?

#2 kathyastro

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Posted 17 October 2021 - 09:09 AM

I believe NINA has an option to re-centre the target via another plate-solve after a meridian flip.


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#3 Forward Scatter

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Posted 17 October 2021 - 09:16 AM

It's found in the Options>Imaging tab. Top right corner, there is a button for "Recenter after flip". Turn this on and it's almost magic!


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#4 jonnybravo0311

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Posted 17 October 2021 - 09:18 AM

Depending on the version of NINA you're using, you can even setup an instruction to re-center should the target drift too far (it's called "Center After Drift"). Also, in your settings for meridian flip, you can tell it to re-center as well under options -> imaging -> meridian flip, there's a toggle for it.



#5 Tecc77

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Posted 17 October 2021 - 09:20 AM

I’ll need to check. I assumed this was already in play, maybe by default, because I saw NINA say the target wasn’t in tolerance and was syncing the mount.

If I’m not mistaken it slewed slightly off target and then back. Then plate solved again. After this operation it still comes back off target. To your point, I’ve never checked any settings for this.

Edited by Tecc77, 17 October 2021 - 09:21 AM.


#6 scopewizard

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Posted 17 October 2021 - 09:24 AM

For a proper meridian flip in NINA, Options/Imaging has to be set properly. In Sequencer make sure you turn on Meridian Flip settings.

 

It looks to me that your mount did the flip on its own.

The meridian flip settings in NINA has to happen prior to the mount flip settings (the one in your telescope hand controller or software).


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#7 Tecc77

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Posted 17 October 2021 - 09:25 AM

What version of NINA “should” I be using? I run NINA on a mini, which isn’t connected to the internet under normal conditions.

#8 Tecc77

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Posted 17 October 2021 - 09:28 AM

For a proper meridian flip in NINA, Options/Imaging has to be set properly. In Sequencer make sure you turn on Meridian Flip settings.

It looks to me that your mount did the flip on its own.
The meridian flip settings in NINA has to happen prior to the mount flip settings (the one in your telescope hand controller or software).



#9 Tecc77

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Posted 17 October 2021 - 09:32 AM

Interesting. If I understood you, the thought here is my CGX mount called for a flip prior to NINA?

I must be misunderstanding. I watched NINA count down to the flip. For example, the target reached the meridian at X time, and the flip was at Z time. The sequence paused and did the flip count down as scheduled.

#10 jonnybravo0311

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Posted 17 October 2021 - 09:34 AM

What version of NINA “should” I be using? I run NINA on a mini, which isn’t connected to the internet under normal conditions.

Whichever you're comfortable using. I use the nightly builds, because I like the new advanced sequencer and plugin features provided in 1.11. Plenty of people are still using the 1.10 stable release as well. The meridian flip options for re-centering exist in 1.10 and 1.11 if I recall correctly.



#11 scopewizard

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Posted 17 October 2021 - 09:47 AM

Interesting. If I understood you, the thought here is my CGX mount called for a flip prior to NINA?

I must be misunderstanding. I watched NINA count down to the flip. For example, the target reached the meridian at X time, and the flip was at Z time. The sequence paused and did the flip count down as scheduled.

Ok, strange that it did not recenter. I have a CGX which does the flip and recenter every times.

I used the latest 1.11 #NIGHTLY 153. Last session was Thursday, Elephant Trunk with a flip around 10pm local, no issues.

Mine is set to pause 1 min prior, wait for 5 mins after the meridian, flip,  settle 15s after flip, recenter on and auto-focus on. Recenter is plate solve and center.

I use a minipc remotely.



#12 scopewizard

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Posted 17 October 2021 - 09:53 AM

I forgot to add, in CPWI, under mount settings "RA Slewlimits" are for East and West set to -5.

I don't want my scope to hit the mount so it is set low but long enough to be done by NINA first.


Edited by scopewizard, 17 October 2021 - 09:54 AM.


#13 Tecc77

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Posted 17 October 2021 - 09:55 AM

I forgot to add, in CPWI, under mount settings "RA Slewlimits" are for East and West set to -5.
I don't want my scope to hit the mount so it is set low but long enough to be done by NINA first.



#14 Tecc77

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Posted 17 October 2021 - 09:57 AM

I think I’m using -2. I haven’t hit anything yet. I have snagged my cables a time or two on the CGX clutch release. I wish they were quick release handles that I could pop off.

#15 ngatel

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Posted 17 October 2021 - 11:46 AM

 Sometime later, after the auto meridian flip, you notice the image is in focus, but is no longer centered. It’s as much as an inch off from the center of your original framed center.
 

 

So you notice the change a period of time after the meridian flip? If so, you probably have a guiding issue.

 

I have a CGX and have been imaging with NINA 1.10 since January of this year. I live in a desert and am retired, so I image almost every night, usually on a single target all night long, which almost always requires a meridian flip.

 

I am pretty sure the CGX cannot do a meridian flip on its own.

 

I have had the same issue as you a few times. PHD2 loses the guide star due to low SNR and quits guiding, or a couple of times a USB connection issue. At the top of the PHD2 screen will be an error message that PHD2 cannot communicate with the mount, or something similar. So since PHD2 has quit guiding, the mount slowly drifts off center.



#16 Tecc77

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Posted 17 October 2021 - 02:42 PM

So you notice the change a period of time after the meridian flip? If so, you probably have a guiding issue.

I have a CGX and have been imaging with NINA 1.10 since January of this year. I live in a desert and am retired, so I image almost every night, usually on a single target all night long, which almost always requires a meridian flip.

I am pretty sure the CGX cannot do a meridian flip on its own.

I have had the same issue as you a few times. PHD2 loses the guide star due to low SNR and quits guiding, or a couple of times a USB connection issue. At the top of the PHD2 screen will be an error message that PHD2 cannot communicate with the mount, or something similar. So since PHD2 has quit guiding, the mount slowly drifts off center.



#17 Tecc77

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Posted 17 October 2021 - 02:48 PM

I noticed it sometime later, but when looking at the image history I find the very first exposure after the flip was off center. On a separate night I sat with it and watched closely. The guiding paused, meridian flip countdown timer started, and then it flipped. Shortly after it plate solved, and found it was outside of limits so it slewed back in. Then an autofocus routine…then back to my sequence.

This is likely an obvious, and familiar step-by-step process to everyone here. Sorry to ramble. Point being, after all that, the image was off center.

I’m using ASTAP. Not sure if that matters.

#18 ngatel

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Posted 17 October 2021 - 03:10 PM

I use ASTAP. There is a setting in the Plate Solve page for accuracy. Mine is set to something like < 1 or 2 degrees. If it is set too high, NINA’s centering won’t be too accurate.

Edit: I think my tolerance in the NINA plate solve set page is < 1 or 2 minutes not degrees, as scopewizard mentioned. I think the default was something 5, which wasn’t very accurate.

I import the coordinates from Stellarium and NINA does everything else flawlessly 99% of the time. The only real issues I have had with NINA was some of the initial set-up parameters, mostly because I was too lazy to read the instructions closely.

Edited by ngatel, 17 October 2021 - 04:19 PM.


#19 scopewizard

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Posted 17 October 2021 - 03:23 PM

The CGX will not do a meridian flip unless repeat the goto target.

In Options\Plate Solving what is your plate solving tolerance, mine is 1 min.

When you create a sequence in the framing window, the RA and Dec will change in your sequence based on the frame having move from the Stellarium position. When you view your sequence, you will notice that the position stated is not the same as the one in Framing. In framing you are seeing the Stellarium position. If you brought the position just before you started the sequence and the scope has already been centered, the next request will move the scope to the position you imported before starting the sequence. I have done that, not good.

In my sequences, I always turn on cool the camera, meridian flip settings and in Target Options, I turn on slew to target, center target and start guiding.

 

I does not matter if they are already doing it. On the first image taken I will seen if any settings are off. Munch better knowing right away then 2 hours later.



#20 Tecc77

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Posted 17 October 2021 - 03:52 PM

Maybe I’m doing this entirely wrong?

I have my scope and camera (sensor) built in Stellarium. I use that to frame my target, and then click “current object” under telescope control. I also slew to the object in Stellarium.

Back in NINA, I bring in the coordinates, which are presumably those locked in when I clicked “current object”. Or maybe it’s current position. Either way, that’s my process.

I’ve just (literally) updated to 1.11 nightly, which is a totally different layout. I’ll get my bearings and report back on my settings. I appreciate the help.

#21 SnowWolf

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Posted 17 October 2021 - 04:45 PM

One thing that needs to be set is the target in the sequence.  If that hasn't been set, after the flip, NINA will sync on wherever the mount thought it was pointing.  But, after several hours of dithering, that may not match the actual target.



#22 Tecc77

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Posted 07 November 2021 - 07:32 PM

Depending on the version of NINA you're using, you can even setup an instruction to re-center should the target drift too far (it's called "Center After Drift"). Also, in your settings for meridian flip, you can tell it to re-center as well under options -> imaging -> meridian flip, there's a toggle for it.

I’m not sure if you’re still following this thread, but I have a follow-up question. I’m solved my original issue. My framing after flips is back in tolerance. I’m running the latest version of Nightly, but I’m not clear on the “Center After Drift” feature you mention, Will you elaborate?

 

If it matters, I dither every three, typically. Lately I have been running bright nebula for 6+ hours. I’m sure there’s drift, but I’m asleep.  



#23 jonnybravo0311

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Posted 07 November 2021 - 07:45 PM

I’m not sure if you’re still following this thread, but I have a follow-up question. I’m solved my original issue. My framing after flips is back in tolerance. I’m running the latest version of Nightly, but I’m not clear on the “Center After Drift” feature you mention, Will you elaborate?

 

If it matters, I dither every three, typically. Lately I have been running bright nebula for 6+ hours. I’m sure there’s drift, but I’m asleep.  

The "Center After Drift" does a quick plate solve after every image (it's a parallel instruction, so it's not eating into your imaging time). If it determines you're too far out of tolerance (a value you set in the trigger when you add it to your sequence), it will execute a slew and center command and plate solve to get your target centered again.



#24 Tecc77

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Posted 07 November 2021 - 07:52 PM

The "Center After Drift" does a quick plate solve after every image (it's a parallel instruction, so it's not eating into your imaging time). If it determines you're too far out of tolerance (a value you set in the trigger when you add it to your sequence), it will execute a slew and center command and plate solve to get your target centered again.

Do I need to enable this feature? I guess I’ve overlooked it (multiple times). 



#25 jonnybravo0311

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Posted 07 November 2021 - 08:17 PM

Do I need to enable this feature? I guess I’ve overlooked it (multiple times). 

It's in the advanced sequencer. You "enable" it by including it as a trigger condition in your instructions.




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