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Corner artifacts with N10 and SBIG STL-11000

Flat N10 STL-11000

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#1 rbrecher

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Posted 03 March 2014 - 03:12 PM

Hello all

 

I use an N10 with an SBIG STL-11K camera, and a LRGBHa filter set from Baader.  I have always had corner artifacts that are not corrected using twilight flats.  Please use the following link to download files to help me iagnose this problem:

 

https://www.dropbox....e3nk/DBvcAxj0qZ

 

I have posted raw and calibrated single frames, the twilight flat used to calibrate (stack of 16) and the finished image.  My Ha filter does not show this defect, but all the others do to varying degrees. I can just about correct this using DBE, but I do have to crop at least a little, and I would rather not have to do this.

 

Anyone have any ideas what could be causing this?  It's like the flat is overcorrecting the corners.  I am considering upgrading to a camera with a larger chip (e.g. 16803).  Perhaps my current camera is not ideal for a scope this fast?  In that case, what large chip camera do people recommend for use with this scope?

 

Thanks for your insights and advice.

 

Clear skies,

Ron



#2 gmalits

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Posted 04 March 2014 - 08:34 PM

Hi Ron,

 

I think you are using 2" Filters, like me (mine is an atik 11000 with efw2 filterwheel, 2" screwed in filters), the vignetting is simlar to my setup.

the chip ist ok, the filtersize ist the proplem in this fast f3.6 setup.

is it possible to use large square filters (50x50 mm) with the build in filterwheel of the STL-11k? this would reduce the hard vignetting.


Edited by gmalits, 04 March 2014 - 08:35 PM.

regards, Gerald
---------------------------------

DDM85S / 10N-OK3 f3.6


#3 gmalits

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Posted 04 March 2014 - 08:47 PM

I measured your masterflat in CCD Inspector, the vignetting in the corner is over 60% !  Ithink, the flat cant compensate such strong vignetting.

I also crop my pix....

Attached Files


Edited by gmalits, 04 March 2014 - 08:50 PM.

regards, Gerald
---------------------------------

DDM85S / 10N-OK3 f3.6


#4 Konihlav

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Posted 13 March 2014 - 05:04 PM

some STL user's flat:

http://blog.astrofot...ttingAtF3_6.jpg

 

my G3-11000 flat:

http://blog.astrofot...gNEWadapter.jpg


Edited by Konihlav, 13 March 2014 - 05:05 PM.





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