Re: [APML] Very Deep Seagull Nebula

[Matt BenDaniel <matt@starmatt.com>]

swalters@att.net wrote:
> 
> Matt,
> 
> That's very impressive.

Thanks and I'll pass your appreciation on to Steve Mandel.

> Can you say a bit more about whatever problems you had
> combining them? I'm mostly curious about issues due to
> mixing CCD and scanned film.

I've combined both CCD and tech pan (H-a and full spectrum) images with
my color film images.  Assuming the source data is well prepared, I
don't think there's a lot of difference whether it comes from CCD or
film.

The most obvious issue is that greyscale images usually have to be
reduced in contrast to combine with a color image.

The colors in this image (the CCD was used as red channel, NOT L) turned
out to be too intense for my taste, so I desaturated them slightly.

Preparing my original color film image (99% full frame!) for standalone
presentation was a lot of work (as usual). The anti-vignetting was the
biggest issue.  See article on my web site.

I'll have to shoot the Seagull on film again sometime.  I know I can go
deeper!  See:
http://members.home.net/dachurchill/northern/155/A0936.html

> What do you think might improve this method? (not that
> it looks to need much improvement!)

Hmm.  I don't know.  You tell me.

> Was it any more difficult getting good color balance
> with the CCD/film component differences than from LAB or
> RGB film methods?

Because I combined the H-a data in red channel, not luminosity, I had no
need for LAB.

Even with full-sprectrum L channel compositing, you can stay in RGB
mode, if you introduce it as a layer using the luminosity function. 
See:
http://people.ne.mediaone.net/mbendaniel1/gallery/astro/hh.html

> Any problems getting alignment due to differing pel sizing?

I registered my color image with Steve's as the reference.  RegiStar
scales automatically.  My 6 arcsec stars scaled down to about one pixel
FWHM, the same as what Steve got.

> Nice work!

Thanks!

Matt
http://starmatt.com

--  APML Archives at <http://astro.umsystem.edu/apml/>  ---
             Unsubscribe at <majordomo@seds.org>