First Bi-Colour Narrowband Image

[ozstronomer]

Hi All,

I have seen some great Bi-colour Narrowband images on the forums so I've decided to give it a try.

This is 2 hrs of Ha and 3.5 hrs of OIII. Frames have had darks and Flats applied.

The Ha nebulosity is prominent but the OIII doesn't appear to have added anything to the overall image except to add a blue cast.

The attached screen shot shows the layers. Hue/Saturation is as follows.

Ha H=0, S= 100, L=-50
1st OIII H= 133, S=100, L=-50
2nd OIII H=240, S=100, L=-50

The image I have seen of NGC 6188 has the OIII really adding to the Ha and giving it extra depth. maybe this is just the wrong target?

Any help or suggestions gratefully appreciated

Thanks Geoff

[gregbradley]

Not bad at all for a first time at this.

The formula I use is Ha is red O111 is blue and green is made by combining Ha and O111 and using pixel maths to divide it in 2.

I use CCDstack to do this.

Perhaps also there is a gradient here that needs to be addressed but try the above first.

Greg.

[ozstronomer]

Hi Greg

Thanks for the suggestion however I don't have CCDstack so is there a way to do it in Photoshop

[gregbradley]

I would open Ha and O111 in a layer each. I would adjust the opacity or the fill slider to 50% and then flatten those 2 and save the result.
I would then open that combined result and delete the red and blue channel.

Then I would do layers in Ha and O111. Delete the green and blue channel in the Ha layer and the red and green layer in the O111.

Adjust the opacities of each layer until you get a pleasing result.

Then save it as a .psd file so you can open it again with all the layers intact should you want to change something.

I haven't done this myself but it should work.

Greg.

[RickS]

A good start, Geoff! Everybody seems to have a different recipe for bi-colour. Here are a few I've tried:

R=Ha B=O3 G=0.2Ha+O3
R=Ha B=O3 G=0.45Ha+0.55O3
R=Ha B=O3+0.15Ha/1.15 G=O3

Not all objects have interesting amounts of OIII.

Cheers,
Rick.

[ozstronomer]

Thanks Greg and Rick, I'll give that a go

Cheers Geoff

[Ross G]

Hi Geoff,

Great photo for a first attempt.

Good luck.

Ross.

[stevous67]

Thats a great looking image Geoff - excellent.

Steve