Re: [APML] Comet Q4, M46, M47 & M93...

[astropix@att.net (Geoff Powers)]

 On Mon, 17 May 2004 07:10:52 +0000, Dominic Cantin writes:
> Thanks Geoff for these clarifications !

 Hey Dom...

     Just remember... take it with a grain of salt... your results may vary!

> I'll see if my supra will go blue fast with the schmidt-camera this week.

     Hope the sky cooperates with your effort! Post the results here, by all means! The steps I'm taking in post-processing *may* contribute some to the blue saturation, but it does seem that most of it is film response. Here's a link to the 'raw', un-stretched image:

      http://home.att.net/~astropix/scan1_stack.html

... the above image is the result of a multi-pass scan, with the scanner in 'Image' mode, generating a *negative* image file, just as the film original. I then made gamma-biased copies of the RGB in PW's 'Color/Negative', run those through PW's 'Advanced Sharpen', then made the positive by putting these RGB's into 'Stack Images' at 100% each. For reference, see:

      http://home.att.net/~astropix/guide_PW_Pro_3.5.html

... the 'Curves' in the above linked 'raw' image are linear, and the 'Histogram' of each RGB channel looks very good, but the pixel counts are higher for the 'Blue' channel. 

     It seems *most* of this is indeed film, but I may very well be missing something here that is skewing the color balance slightly. The M42 shot I used in the guide has a bluish cast as well... but is definitely more neutral than the shorter, faster f-ratio comet shot. 

     Still working on all this... but this routine is working far better than anything else I've tried, with the equipment and skills I have to work with.

 Best...   :o)

--
 Geoff

http://home.att.net/~astropix/
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