Centaurus A

AstroJason (Jason) · #1 26-04-2013, 02:49 PM

Captured this shot of Centaurus A last night. I was up against the full moon and light pollution of Sydney Olympic Park. Taken using my 60D at 200mm. This is a stack of 120 x 60 second exposures. Flats, Darks and Bias' applied.

I had those huge black halos around the brightest stars in the image but I have been learning how to fix them up in photoshop. They aren't entirely corrected but still working on my processing skills.

JZ (Ross) · #2 26-04-2013, 05:16 PM

Nice shot.
I'm new to this stacking caper. Haven't tried it myself as yet.
What causes the black halos, and how do you fix them?

Larryp (Laurie) · #3 26-04-2013, 05:17 PM

Nice result, Jason!

AstroJason (Jason) · #4 27-04-2013, 02:20 PM

Cheers guys. I forgot to add that that was just a 70% crop of the original image. The data was too noisy at 100%.

Ross, I think the dark halos around the stars are due to me using a DSLR lens (which isn't really designed for shooting long exposures of stars at night). The halos are there right out of the camera even before I begin processing. That said they can also be caused by over processing images as well but I have the problem of having them there even before I begin processing

Below is a direct link to a powerpoint presentation which I used to remove the dark halos from around the stars using photoshop.

Remove Dark Halos

JZ (Ross) · #5 30-04-2013, 01:31 PM

Hi Jason,

Thanks for the explanation and the powerpoint.
I have not noticed the halos in my shots (I've only done a few so far).
I'll have to go back and have a closer look.