From: "milton_aupperle" <milton@outcastsoft.com>

Date: February 15, 2010 1:01:14 PM MST

To: Astro_IIDC@yahoogroups.com

Subject: Re: Mars: RGB vs L(IR)RGB

Hi Antonio;

For LRGB filtered imaging, I color balance using a G2V star and shoot separate L R G B filtered images at the same exposure time.

I outlined the procedure I use for this to this list on November 19, 2009 and then again on December 8, 2009.

Yahoo is hopeless for searching, so you'll have to manually flip back to them to find them.

You can find lists of many G2V star easily with Google :

http://www.skymap.com/g2v.htm (list of 627 stars)

and

http://starizona.com/acb/ccd/advtheorycolor.aspx (near the bottom, plus a good description of how we perceive color)

or just searching with the phrase "G2V Star".

HTH..

Milton Aupperle

--- In Astro_IIDC@yahoogroups.com, "aa27100" <antonio.agnesi@...> wrote:

Thanks Alan (and Willie, Milton)!

How do you weigh the color channels captured through RGB filters? I usually tend to calibrate the white point on the "white" feature of the image (polar cap on Mars, rings on Saturn, white bands on Jupiter). Maybe taking a picture of a sunlit white sheet of paper is a better way to have an absolute calibration... (not sure about what to do with the IR)

Thanks for your valuable suggestions!

Antonio

-