Re: [APML] Rising Emu

["Marco Lorenzi" <lorenzi@libero.it>]

Grat Axel! A curiosity: did you ever experienced any problem with dew in
Namibia? I think it should be quite dry but I have no idea what happens
during the night...
Marco

----- Original Message -----
From: "Axel Mellinger" <axm2@canopus.physik.uni-potsdam.de>
To: <astro-photo@seds.org>
Sent: Monday, May 20, 2002 10:59 PM
Subject: Re: [APML] Rising Emu


> On Mon, 20 May 2002, Volker Wendel wrote:
>
> > this is a great shot! How did you get the background color so neutral?
>
> Volker,
>
> the images were "flat-fielded" by subtracting an unsharp mask consisting
> of a Gaussian-blurred version of the original image. Of course, I had to
> remove the Milky Way star clouds from the mask by hand; otherwise, they
> would have been "flat-fielded", too.
>
> > Another question (because I´m in Namibia in July too): how do you plan
such
> > mosaic shots? Do you look for the center of the area for every shot and
how
> > much do you overlap the frames?
>
> In the text below the mosaic, there is a hyperlink titled "4-frame mosaic"
> that will open a little JPEG file with the four raw images. As you can
> see, I try to get about 20% overlap. Sometimes this is not trivial to
> achieve, especially in areas with few bright stars (when it is hard to see
> anything at all in the viewfinder). It is always a good idea to sketch the
> frames in a star chart, especially when your exposures are several nights
> apart.
>
> Clear skies,
>
> Axel
>
> --
> Axel Mellinger  <http://canopus.physik.uni-potsdam.de/~axm/astrophot.html>
>
>
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