Friday, April 8, 2016

Astrophoto Flat Field Illustration

This is to demonstrate the effect of taking "flat" frames to clean up errors in the optical system, such as due to dust-motes or vignetting. (Bias and dark frame subtraction are another matter.)

First up is an unprocessed single frame light image ....





Now, here is the flat frame, taken the next morning. (Note the dust mote just above and left of center and the more pronounced ones toward the bottom.) ...

 
And here is the resulting frame after applying the flat frame.  (Still needs a little work but I think you get the point. Another reason to crop) ...
 
 
No noise reduction or bias frames were applied, just to show only the effect of applying a flat frame.
 
Flat frames are worth the effort.
 
William Shaheen
 

 

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