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Weird stars with 294mm pro

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#1 Eric Horton

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Posted 09 June 2021 - 09:53 PM

First time connecting my 294mm pro to my skywatcher quattro 10" with skywatcher field flattener.  I have not been happy with the stars at all and very frustrating as last year the 294mc pro worked well on this same scope.  

 

Tonight i spent more time with the problem and basically learned that it is something with the 294mm pro camera.  I rotated the camera and the problem rotates.  I take the camera out and put in the 294mm pro and back to regular looking stars.  

 

I know that the pixel sizes are very different with the 294mm pro being at 2.31 and the 294mc pro at 4.62 and wonder if this is the problem.  If that is the case, is there any solution to use this scope with the 294mm pro?

 

I have pasted here a zoomed in portion of a couple of the stars so you can see how it almost appears a "bite" has been take out or a notch is out of the star.   With the 294mm pro I played with gain and offset, really no change to the way the star looks.  Normally I would say something in the light path until I put the 294mc pro on and it doesn't have the problem.

 

Anyone with this scope and camera?  Any ideas on how to correct of if I can correct?  

 

As always, I appreciate any help or guidance.

 

Screen Shot 2021-06-09 at 10.44.34 PM.png



#2 Dynan

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Posted 09 June 2021 - 10:20 PM

I believe you have a typo in here:

"Tonight i spent more time with the problem and basically learned that it is something with the 294mm pro (294MC-Pro ?camera.  I rotated the camera and the problem rotates.  I take the camera out and put in the 294mm pro and back to regular looking stars."

 

You don't say if you're using an OAG for guiding.

 

Even though the sensor size is exactly the same in both cameras, could one be orienting differently to the OAG prism stalk, thereby causing an intrusion into the light cone for one and not the other? (Not aligning to the long side of the MC sensor?)

 

If you're not using an OAG, nevermind... I got nothin'.



#3 Eric Horton

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Posted 09 June 2021 - 11:42 PM

Sorry you are correct.  The problem is with the 294mm pro the 294mc pro works fine.  No OAG.  just flattener, spacers and then camera.   I took the filter wheel out of the equation too.



#4 rzgp33

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Posted 10 June 2021 - 02:29 AM

NB the two cameras have different sensors

 

294mc  IMX294

294mm IMX492

 

The image looks weird.  Almost like tilted coma... are all stars like that or just in the corners? Double check the required spacing etc.

 

You are doing the right thing in simplifying.

 

Have you tried binning the 294mm? then you would have the same pixel size (4.6)? one more thing to simplify.

Next I would remove the flattener and then try the 294mm with another scope etc.

 

 Apart from that I got nothin' either.



#5 Dynan

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Posted 10 June 2021 - 05:46 AM

Please let us know if/when you find the culprit...curiouser and curiouser...hmm.gif



#6 Jinux

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Posted 10 June 2021 - 11:54 AM

Um.... packman cluster?

 

sorry, couldn't resist.

I'm using 294mm and haven't found these.


Edited by Jinux, 10 June 2021 - 12:40 PM.


#7 Eric Horton

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Posted 10 June 2021 - 12:57 PM

Um.... packman cluster?

 

sorry, couldn't resist.

I'm using 294mm and haven't found these.

That's what I was going for.  But unfortunately, there's only so many of those I can take :) :)



#8 Eric Horton

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Posted 11 June 2021 - 06:28 AM

NB the two cameras have different sensors

 

294mc  IMX294

294mm IMX492

 

The image looks weird.  Almost like tilted coma... are all stars like that or just in the corners? Double check the required spacing etc.

 

You are doing the right thing in simplifying.

 

Have you tried binning the 294mm? then you would have the same pixel size (4.6)? one more thing to simplify.

Next I would remove the flattener and then try the 294mm with another scope etc.

 

 Apart from that I got nothin' either.

I was hoping to of had clear skies last night to try removing the field flattener but that did not happen.  I have tried different binning options up to 4.   I will post back when I can get some clear and try this.  Thanks!!




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