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  #21  
Old 20-09-2011, 05:23 AM
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Rob,

I meant the illumination on the LHS is not the same as on the RHS. This looked different to the typical vignetting pattern where the corners are all dark and the centre light but it could be a bit of both.
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  #22  
Old 20-09-2011, 05:29 PM
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I only ask because I feel I have to apply more flat/vignetting correction to city images than dark sky, which I've found counter-intuitive.
Yet another flats mystery. Some great info in this thread.
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  #23  
Old 20-09-2011, 08:57 PM
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Rob,

I was also surprised that the dark site image calibration was different to the city. I need to spend some more time looking into this to work out what is going on. Hoping to get some time on Friday.

Peter
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  #24  
Old 28-12-2014, 07:38 PM
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philiphart (Phil Hart)
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Just thanking people (especially Marc) for the contributions to this old thread. Helped me with the same issue today which I've had a few times recently but only now had the time to debug.

I was getting strongly over-corrected images using PixInsight (probably ImagesPlus also if I recall the last time I used it). Adding Bias frames and reducing the brightness of the flat has much improved the result. Not actually sure which of those two did the trick but I'm a happy chappy now.

DBE in PixInsight is now freed up to fix the remaining issues more easily .

Phil
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  #25  
Old 06-01-2015, 10:34 PM
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Quote:
Originally Posted by philiphart View Post
Just thanking people (especially Marc) for the contributions to this old thread. Helped me with the same issue today which I've had a few times recently but only now had the time to debug.

I was getting strongly over-corrected images using PixInsight (probably ImagesPlus also if I recall the last time I used it). Adding Bias frames and reducing the brightness of the flat has much improved the result. Not actually sure which of those two did the trick but I'm a happy chappy now.

DBE in PixInsight is now freed up to fix the remaining issues more easily .

Phil
Its reassuring to hear even the photography masters sometimes struggle with flats Phil.
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  #26  
Old 07-01-2015, 09:04 AM
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Its reassuring to hear even the photography masters sometimes struggle with flats Phil.
LOL Rob

Master or not I can assure you I have lots of struggles!

Phil
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  #27  
Old 07-01-2015, 05:48 PM
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Quote:
Originally Posted by philiphart View Post
I was getting strongly over-corrected images using PixInsight (probably ImagesPlus also if I recall the last time I used it). Adding Bias frames and reducing the brightness of the flat has much improved the result. Not actually sure which of those two did the trick but I'm a happy chappy now.
I'm pretty confident it was the brightness of the flats; I've had this happen to me before. The next time I went through the exact same process but reduced the exposure of the flats and everything worked perfectly.
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