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#1 arrowspace90

arrowspace90

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Posted 04 March 2024 - 12:40 PM

Im shooting M81 for about the 5th year, like a million other people.

Ok, so this year, Im using a nice Tak E160ED without a rotator.   So far, with almost zero clear nights near dark of the moon, I have the "R" and the "G", and they look fine.  Got the "B" to go, but then the new thing this year is that I bought a mono Ha filter.  Hoping to bring out M83, etc.

 

But here's the problem, I have the 5 position ZWO filter wheel.  For the RGB, I have left the camera on the Tak to prevent rotation of the image.  But, those 5 filter slots are full.  I bought a new 7 position EFW (I will be selling the old one), but if I remove the 5 position and install everything in the 7 position for the new Ha, I will likely introduce rotation.  I have had a problem with this in the past.  Even a few degrees of rotation become a problem in processing.

 

How would you solve this?  I use PixInsight.



#2 gcardona

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Posted 04 March 2024 - 12:47 PM

Plate solve you R or G images and find the rotation angle. Change your filter wheel, then plate solve some test images with your new setup to match the rotation angle of your R's or G's. You should be able to get within 1 deg., which is easily compensated for in the registration process. Registration will compensate for several degrees of rotation, but then you may have tor crop to get rid of registration artifacts at the edges.


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