Struggling with WBPP Registration

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Patrick Jasanis avatar
I recently switched back to my Williams Optic 81 Zenithstar telescope, with a ZWO2600MC Pro camera.  I have a ZWO OAG.  I've previously used this configuration before and not had issues.  I added in the Williams Optic 0.8 reducer this time.

When I process my images in WBPP, I am getting a significant number of registration failures.

I think that my backfocus is good (60 mm for the WO with the 0.8 reducer).  If the backfocus is off, could this cause registration issues?

Any other suggestions of what I should be checking? 

Thanks in advance, I've never had this issue over the last couple of years.  Kind of baffled.
Patrick
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Joey Conenna avatar
If the there is enough distortion then the registration process may have issues.

Open some raw frames in Pixinsight. Open StarAlignment process, select one as the Reference Image, and the others as targets. Run it and see if it fails. You may want to adjust the registration model to something that can handle distortion better. Even if it works, inspect the output registered images to make sure they look well registered to the reference image. You can place an output registered image on top of the reference image in the workspace and press ctrl-PageDown to "blink" between them. Once you are satisfied, change the Registration parameters in WBPP to those that worked.
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Christian Bennich avatar
Maybe a silly question - have you blinked your images, and double checked the quality??

I recently experienced similar issues, and I had literally forgot to blink one of my channels, which gave me all sorts of trouble.
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AstroCapture325 avatar
Patrick, 
I have the same configuration as you (minus the OAG). Regarding the backfocus, is your flattener/reducer set to 5mm?

Jim
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Patrick Jasanis avatar
Christian Bennich:
Maybe a silly question - have you blinked your images, and double checked the quality??

I recently experienced similar issues, and I had literally forgot to blink one of my channels, which gave me all sorts of trouble.

Yes, I blinked them and thought I had good images.  I will try again.
Patrick Jasanis avatar
AstroCapture325:
Patrick, 
I have the same configuration as you (minus the OAG). Regarding the backfocus, is your flattener/reducer set to 5mm?

Jim

I'm going to double check that I didn't move it.  That is what I selected originally.
Patrick Jasanis avatar
Joey Conenna:
If the there is enough distortion then the registration process may have issues.

Open some raw frames in Pixinsight. Open StarAlignment process, select one as the Reference Image, and the others as targets. Run it and see if it fails. You may want to adjust the registration model to something that can handle distortion better. Even if it works, inspect the output registered images to make sure they look well registered to the reference image. You can place an output registered image on top of the reference image in the workspace and press ctrl-PageDown to "blink" between them. Once you are satisfied, change the Registration parameters in WBPP to those that worked.

Thank you - Will try this later this evening.
Robert Žibreg avatar
Also enable Distortion Correction when stacking. Think it's under registration options, just a checkbox
Tom Engwall avatar
I suspect your back focus is not close enough. At 60 mm , you are 5mm too long. Best to get no more than 1 mm off.
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AnaTa avatar
Patrick Jasanis:
I recently switched back to my Williams Optic 81 Zenithstar telescope, with a ZWO2600MC Pro camera.  I have a ZWO OAG.  I've previously used this configuration before and not had issues.  I added in the Williams Optic 0.8 reducer this time.

When I process my images in WBPP, I am getting a significant number of registration failures.

I think that my backfocus is good (60 mm for the WO with the 0.8 reducer).  If the backfocus is off, could this cause registration issues?

Any other suggestions of what I should be checking? 

Thanks in advance, I've never had this issue over the last couple of years.  Kind of baffled.
Patrick

Listed by others suggestions are great. You could also check out info in FITS readers for several files. Once I had bizarre event when right in middle of session, 3008x3008 chip became 3004x3008. A lot of registrations failed in WBPP. Took a while until I figured out the reason.
Clear Skies!
Armen
Charles Bradshaw avatar
Tom Engwall:
I suspect your back focus is not close enough. At 60 mm , you are 5mm too long. Best to get no more than 1 mm off.

I second this.  Most reducer/flattners have a back focus of 55 mm from the flattner's back.
JohnAdastra avatar
You might try loading your calibrated/debayered images into StarAlignment and ImageIntegration and see if they will stack there. You can try some various pixel rejection settings to see if that works any better. Try increasing clamping threshold and number of points used. You could also do a batch process on the same folder with BlurX in correct only mode to fix up the stars a bit before integrating.
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AstroCapture325 avatar
According to my files, the Flat6AIII has a backfocus of 60.2mm when used with Z81.

16.5 + 21 + 17.5 + 5.2 = 60.2mm

Extender + filter drawer  + 2600MC + Flat6AIII
AnaTa avatar
Charles Bradshaw:
Tom Engwall:
I suspect your back focus is not close enough. At 60 mm , you are 5mm too long. Best to get no more than 1 mm off.

I second this.  Most reducer/flattners have a back focus of 55 mm from the flattner's back.

 Backfocus for other flatteners is irrelevant here. For this particular reducer backfocus is 60.2mm
Oscar avatar
(deleted)
Charles Bradshaw avatar
I stand corrected.
Frédéric Ruciak avatar
Hi, in order to be sure that your backfocus is good, you can use hocus focus plugin in NINA and check the curvature of your image field. The larger, the better of course and below some value (related to your critical focuse zone) you can have distorted corners/edges that complicate the registration. In some configuration a spacer of 0.5mm plus or minus makes a great differrence in field curvature.
Frédéric
Michael Jarvis avatar
In addition to all the valuable suggestions provided so far. you might consider stacking your data with another program (e.g. Deep Sky Stacker).  It may safe some of the data you have already captured.
Jaume Guillamon avatar
Joey Conenna:
If the there is enough distortion then the registration process may have issues.

Open some raw frames in Pixinsight. Open StarAlignment process, select one as the Reference Image, and the others as targets. Run it and see if it fails. You may want to adjust the registration model to something that can handle distortion better. Even if it works, inspect the output registered images to make sure they look well registered to the reference image. You can place an output registered image on top of the reference image in the workspace and press ctrl-PageDown to "blink" between them. Once you are satisfied, change the Registration parameters in WBPP to those that worked.

I had this problem  as well, just put 2 or 3 in Noise Reduction on registration parameters.

Best regards.
Jaume Guillamon avatar
AnaTa:
Patrick Jasanis:
I recently switched back to my Williams Optic 81 Zenithstar telescope, with a ZWO2600MC Pro camera.  I have a ZWO OAG.  I've previously used this configuration before and not had issues.  I added in the Williams Optic 0.8 reducer this time.

When I process my images in WBPP, I am getting a significant number of registration failures.

I think that my backfocus is good (60 mm for the WO with the 0.8 reducer).  If the backfocus is off, could this cause registration issues?

Any other suggestions of what I should be checking? 

Thanks in advance, I've never had this issue over the last couple of years.  Kind of baffled.
Patrick

Listed by others suggestions are great. You could also check out info in FITS readers for several files. Once I had bizarre event when right in middle of session, 3008x3008 chip became 3004x3008. A lot of registrations failed in WBPP. Took a while until I figured out the reason.
Clear Skies!
Armen

Just put 2 or 3 in noise reduction on image registration parameters.
Best regards.
David Cruz avatar
On WBPP in the image integration tab, check the value in 'minimum height'. The default is 0.05, which means that all subs with at least 95% image quality of the best sub is integrated. Check if the value you have makes sense to the subs you got. If you want less frames rejected increase the value. I usually use 0.25 so all subs with at least 75% image quality compared to the best sub will be integrated.

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Bradley Hargrave avatar
You had mentioned you switched scopes. I would check the Image Plate Solver Script and make sure you've set the correct pixel size and image scale for the (Z81, 2600m, focal reducer)
Mike Sample avatar
You might find the back focus adjustment paper at WO Flattener Back Focus instructions helpful. At the bottom two illustrations are included to show how far and in what direction you are off. Examine the stars and compare to those illustrations.

Cheer, Mike
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