M42 6 hours Narrowband

[nebulosity. (Jo)]

I had a try with Nebulosity,

Something a bit different, O111 (red) S2 (green) Ha (blue)

Jo

[DavidNg (David)]

Originally Posted by nebulosity.

I had a try with Nebulosity,

Something a bit different, O111 (red) S2 (green) Ha (blue)

Jo

Thanks Nebulosity, certainly different look and steering away from the unpleasant green.

Originally Posted by troypiggo

Isn't Hydrogen the most common element so makes sense it's more abundant? Have a look at the exposure times that the narrowband gurus like Fred V use. Hours and hours on just SII. Need that to get the signal/noise ratio up so it can be stretched enough to match the Ha.

I used 2 hours each, thanks for letting us know, will try more data in S and O. As I remembered using similar ratio to process Trifit nebula, the green signal was nowhere as strong, perhaps M20 has different composition.

Originally Posted by alpal

Hi David,
I got an interesting effect by reprocessing with swapped Hubble palette.
Now Ha = Red, SII = Green & OIII stayed Blue.
It was reprocessed & then added approximately 50% opacity with the
last pic with normal Hubble palette.
It was then rotated & cropped.
A lot of great detail came popping out.

See here:

http://www.astrobin.com/63180/



cheers
Allan

Love the new colors Allan, great suggestion of images combination. I will try that too , Thanks David

[alpal]

David,

Love the new colors Allan, great suggestion of images combination. I will try that too , Thanks David

Thanks David,
If you don't like green - who does? -
then you can always swap Ha for red.
I think the pic came out in quite agreeable colours.

cheers
Allan

[troypiggo (Troy)]

Here a quick roughy showing Hubble palette (SII to Red channel, Ha to Green, and OIII to Blue) a little more balanced. I was trying to get some blue/cyan and yellows in there. You'll notice when you do that, the stars come out magenta. This is because the Ha in G is so dominant, you stretch the heck out of R and B giving magenta in the stars if you want the nebulosity to be balanced.

Couple of ways to achieve this in PixInsight. For this one, I took your 3 masters, using the LinearFit tool I adopted the Ha as reference image and applied the LF to both the SII and OIII. Then just do a LRGB combination with no L selected, and use each master to each channel. Then do an Auto STF, apply that to a Histogram Stretch, and that's pretty much it. I stopped there because I was just trying to show how to get rid of the dominant green for you.

Another way is to use Pixel Maths. By trial and error you'll find for this image that you need to combine the SII and OIII at 1x, but the Ha you really need to drop down to 0.1x. That is, the Ha is about 10 times as strong as the other channels.

Hope that made sense and helps?