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Old July 6th 07, 07:02 AM posted to alt.binaries.pictures.astro
Rick Johnson[_2_]
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Default ASTRO: Comparison of Pseudo RGB to Direct mapped narrowband



Richard Crisp wrote:

Stefan brought up how the synthetic hbeta rendition of the NGC7K widefield
made using Halpha and [OIII] resembled an RGB nebula

using the same idea but including the [SII] line, I made another such
pseudo-true color image of the Veil region.

in this current case this prescription was used

Red = Ha + 30% [SII] (because the [SII] is in the red spectrum and also is
weak compared to the Halpha)

Green = [OIII]

Blue = [OIII] + Hbeta

Hbeta = 30% * Halpha (approximating the natural 2.92:1 ratio of Ha to Hb)

I took the previous image, disassembled it and reassembled it according to
the prescription above


Here's the updated webpage with the non-downsized resolution versions
linked:

http://www.narrowbandimaging.com/vei...ao3s2_page.htm

For comparison here's a repost of last year's true RGB version of the
western side. The pink regions match though I show blue where your mix
shows green. This was early in my RGB days. I really should redo it.
Also it was with the floppy Meade focuser so stars on one side are
elongated as it couldn't hold the camera in the image plane. Notice how
much darker it is on the left side (inside of the bubble) than on the
right or outside. Seems that bubble really is cleaning out space. If
you hunt hard there's a faint galaxy in the image.

Exposure was L=4x10' RGB 3x10'. Otherwise the same a most of my images
today.

Rick
--
Correct domain name is arvig and it is net not com. Prefix is correct.
Third character is a zero rather than a capital "Oh".

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