From: Roland Roberts <roland
Date: Tue, 04 Apr 2006 12:57:07 -0400
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	Content preview: >>>>> "mk" == Michael Koppelman <lolife
	writes: mk> 3. Take flat fields in each color. Do this at the end of
	the
	night mk> after you have focused. Do not refocus during the night. Use
	a
	twilight/ dawn sky for your flats. Do more than one method if mk> you
	have time and divide one by the other and notice mk> differences. [...]
	pts rule name              description

>>>>> "mk" == Michael Koppelman <lolife

    mk> 3. Take flat fields in each color. Do this at the end of the night
    mk> after you have focused. Do not refocus during the night. Use a
    mk> twilight/ dawn sky for your flats. Do more than one method if
    mk> you have time and divide one by the other and notice
    mk> differences.

For those of us with achromats, I refocus for each color.  Of course, I
requires refocusing.

I think your real point here is (1) flats need to be taken for each
color, and (2) the flats need to be taken at the same focus as the
image, so (3) don't refocus unless you have to and when you do, take new
flats.

regards,

roland
                       PGP Key ID: 66 BC 3B CD
Roland B. Roberts, PhD                             RL Enterprises
roland
roland
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