Blooming stars - help!

[SimonfromSussex]

I managed x9 ha and x6 each RGB subs on the horsehead last night (5 min subs).

Ed80, 0.6 reducer, atik 314L.

Sadly when combined/stacked in maxim dl I've got two quite nasty star blooms.

Usually I can process these out but I've really tried with these and cannot shift them.

Maxim dl has a de-bloom tool but it just gives me purple rings instead?

http://i1190.photobucket.com/albums/z450/simonfromsussex/Horse-LRGB.png

Here is the unprocessed stack:

http://i1190.photobucket.com/albums/z450/simonfromsussex/Horse-LRGBbloom.png

Does anyone have any ideas how to clear/tidy them or is it something I'm doing in capture that causes it?

Simon.

[andrewluck]

These aren't the sort of blooms that Maxim's tool is designed to remove. The Maxim tool is for removing the vertical lines that appear through stars that have saturated an NABG sensor (Non Anti Blooming Gate).

I can't think of any easy answer to your problem as Alnitak is so bright it does tend to spread itself about a bit. Be careful when you're stretching and not pulling the mid-range slider too far to the left is a start.

Is this an HaRGB combination? If so, there is a large difference in size of the stars between the Ha and the colour frames. The Ha stars are a lot smaller. You could try combining the Ha and red frames instead of using the Ha as luminance.

Andrew

[SimonfromSussex]

Thanks Andrew, yes it is an HaRGB combination. I'll try the red blend, cheers.

[andrewluck]

When you perform the non-linear stretches on the red and Ha frames try to ensure that the background areas of the red frame are somewhat brighter than the background areas of the Hydrogen-Alpha frame, while the highlights in the Hydrogen-Alpha frame are somewhat brighter than the highlights in the red frame.

When these frames are combined in Photoshop, paste the Ha on top of the red and change the layer mode to Lighten. This will keep the brightest parts of the two frames and ensure that the stars are retained from the red layer whilst keeping the nebula highlights from the Ha frame.

Use the same stretching values for the blue and green frames as you used for the red. This should make the colour balancing easier.

Andrew

[allcart]

That will be a very nice pic if you can sort out the little problem.

[ollypenrice]

Good advice from Andrew. I never apply more than about 15% of Ha to L for precisely the reasons you see.

Once you have pasted Ha onto red and set Blend Mode Lighten, don't forget that you can play with the curve on the Ha layer to lift or lower it and see the effect it's having on red. I then drop it in at 100% and if the effect is excessive I paste the HaRGB onto the RGB and select the opacity I like.

Olly