Ghosts of Cassiopeia

[dariv]

I've started a new project and I'm wondering what to do about very bright stars?
What can I do to push the color and reflection of the secondary back?

Thanks!
-DaRiv

[Burly]

That is a big halo , what is your imaging setup train camera , filters etc just in case something in imaging train exaggerating effect .

Dave

[dariv]

Orion 8" astrograph F4
GPU Aplanatic coma corrector
Orion thin OAG
ZWO mini electronic filter wheel
Astronomik 1.5" narrow band filter set 6nm
ZWO ASI 1600MM Pro camera

[admin]

Would you be able to post an example?

Secondary reflections are best dealt with during acquisition.
Filters with poor quality coating can also cause significant halos...

[Burly]

It may be worth experimenting with the imaging train to see if any one item is causing the halos

[dariv]

NewComposite.jpg (78.28 KiB) Viewed 12321 times

[admin]

I'd say that's (pretty severe) secondary reflection, clear as day. You can make out the spider vanes and central obstruction.

There is something in your imaging train that is reflecting light back and forth. Try eliminating the variables one by one by imaging a bright star.

[dariv]

Yes, but what can I do to try and salvage this data set?

[admin]

Yes, but what can I do to try and salvage this data set?

That'd require some serious editing/doctoring, however your first plan of attack would be to use the Filter module, which was designed for this sort of thing.
Set Filter Width to max (so it is more targeted), Filter Mode to Reject , and start clicking on the halo.
You can use the Layer module to layer back in the stars (and blue nebulosity) from the original (with a bit of Mask Fuzz to make the transition less stark).
You can further try to mask back things in selectively, pushing quite far into doctoring;

NewComposite2.jpg (71.39 KiB) Viewed 12271 times

[dariv]

Ivo,
That's really amazing what you can accomplish. Can you give more detail about the use of layer in this example? or perhaps post the log of what you did? Two of the modules I hardly ever touch are layer and filter so this kind of new to me. I see how you use the filter. But it kills all the blue in the image. If you try to mask just the halo, you get a big black halo instead. I guess the layer module is used to extract the blue in the image, but not in the halo? and then blend it back in after the filter?