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Help With Lum Flat- Always Seems To Be Overcorrecting??

Tony BenjaminTony Benjamin
edited October 2020 in PixInsight

I have attached 3 pictures of a quick Lum shot of Vdb141 in One Drive:

  • Vdb141 with No Calibration;
  • Vdb141 Fully Calibrated; and
  • Master_Lum_Flat

The Lum Flat consists of 25 frames at 1.63 sec each. I am using an FLI ML16200 which has a Full Well of 39,000e - I used 20,000e for the flats (about 50%). I'm also using an ELP Spike a Fielder flat panel.

 

With no calibration you can easily see the dust motes and the vignetting.

 

With calibration the dust motes are gone (ignore the dead column) but the vignetting is now noticeably "grey" inside of the dark corner of the non-cal image? Is it overcorrecting or is it just me? I think it is overcorrecting and I can't figure out why or how to correct it?

 

So how do you get a proper flat?

 

Here is a link to the .Fit files of the 3 pics.

 

https://1drv.ms/u/s!...I5DgP7?e=OQ0J92
 

Any help sorting this out would be greatly appreciated as this has been an issue for some time.


Three .jpgs are attached as well.



Lum_Master.JPG
1153 x 930 - 52K
Vdb141_Fully_Cal.JPG
1157 x 928 - 124K
Vdb141_No_Cal.JPG
1153 x 927 - 130K

Comments

  • Tony BenjaminTony Benjamin
    I did try the Pixel Math (mysub/mymaster) and it looked fine.

    pixel math.JPG
    1156 x 927 - 273K
  • Tony BenjaminTony Benjamin
    The skies been fairly bright with the moon close to full...maybe thats what causing the overly bright "vignetting"??
  • BlockHeadBlockHead
    I think we are connecting tomorrow.
    If you are the same as GeneralT... then I can see the problem in your procedure.
    -the Blockhead
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