Re: [APML] Scorpius, Sagittarius, and the Milky Way

["Chris Cook" <ccjd@ix.netcom.com>]

Awesome shot Wei-Hao.  Those tight stars are beautiful.  Gotta love that
13,000+ft.... :-)

Take care,

Chris

----------------------------------
Chris Cook
Astronomical & Nightscape Photography
www.abmedia.com/astro


----- Original Message ----- 
From: "Wei-Hao Wang" <whwang@gmail.com>
To: "APML" <astro-photo@seds.org>
Sent: Monday, July 05, 2004 4:11 AM
Subject: [APML] Scorpius, Sagittarius, and the Milky Way


> ALOHA,
>
> A new image is in
> http://www.ifa.hawaii.edu/~wang/gallery/picutres/sco_sgi_milkyway.htm
>
> To correct the vignetting pattern, I used a little crappy but quick
> flat field method.
>
> As I introduced my flat field technique to you about half year ago, I
> took several
> images of daytime sky and average them to make a flat image.  The old way
is
> to nonlinearly match this flat with the sky background in a real
> astronomical image
> and then divide the image with the matched flat image.  This method works
quite
> well.  I had showed the results on my Orion mosaic to you.  However,
> this technique
> may be a little difficult for most people since it requires some computer
> programming.
>
> In order to see if things could be more simple, I divide the image with
the flat
> directly (without any background matching).  The result is the image
above.
> I have to say, this flat fielding is not perfect but the residual
> vignettign pattern
> can be so easily fixed in PhotoShop.  I think this is worth trying.
> You don't need
> to write a C++ program.  All you need is to take a picture of daytime sky
and
> find a image processing software that does division (PhotoShop doesn't).
>
> 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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