Re: [APML] Blue Witch in a Red Sea

[Wei-Hao Wang <whwang@gmail.com>]

Hi Chris,

This is an excellent shot.  That area is indeed full of H-alpha.  This makes
the vignetting removal very difficult because one cannot be 100% sure if it 
is the sky background or nebulas that are removed.  A Schmidt camera 
can easily bypass this problem since it has very little vignetting.

http://www.ifa.hawaii.edu/~wang/gallery/picutres/witch_head.htm
This is my work.  Vignetting is corrected in PixInsight.  Because of the 
nature of vignetting removal, the most extended nebulas are all gone.
The red nebulas in my picture are those whose size is much smaller than
the field of view.  

Another field you may want to try is M45:
http://www.ifa.hawaii.edu/~wang/gallery/picutres/subaru_deep_field.htm
When I processed this image, I had the same problem on vignetting 
removal.  Your Schmidt camera will be the perfect weapon for large scale
nebulas like these.

Cheers,

Wei-Hao

-- 
________________________________________________________________
Wei-Hao Wang  :)

Institute for Astronomy at University of Hawaii

Address:                       
2680 Woodlawn Drive         Personal Website:
Honolulu, HI 96822             http://www.ifa.hawaii.edu/~wang
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