Re: [APML] M13 with Canon 1Ds

["Mike Unsold" <mike@mlunsold.com>]

Hi Jerry

I guess the bright very overcast sky would have a color temp of about
10,000K.
So this would skew the blue to red ratio by a factor of ~2. A white card in
full sun
on a clear blue day would be better. Is there a better substitute for a G2
star???

Mike


----- Original Message -----
From: "Jerry Lodriguss" <jerry@astropix.com>
To: "Discussion of Film Astrophotography" <astro-photo@seds.org>
Sent: Monday, March 17, 2003 12:34 PM
Subject: Re: [APML] M13 with Canon 1Ds


>
> >I am trying to color balance the 1Ds and your comments are most welcome.
> >It appears that the Canon 1Ds has the following white balance factors:
> >
> >H-alpha = 3.65, Red = 1.02, Green = 1.0, OIII = 1.043,
> >H-beta = 1.0, and Blue = 1.01. The factors are based on exposures
> >of a white card and uniform light gray cloudy sky.
>
>
> Hi Mike,
>
> Color balancing under a light gray cloudy sky will make the results biased
> because of the high color temperature of the illumination.
>
> Jerry
>
> Astronomical photography: http://www.astropix.com
>
>
>
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> Astro-Photo@seds.org
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>


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