Bright Blue Stars Create Fuzzy Halo

[1loosetooth]

Hi, I searched the forum but didn't seem to find the right answer to my issue: After I use AutoDev, the brightest stars in my photos develop a fuzzy halo, the brighter and bluer the star, the brighter and larger the fuzzy halo. I tried the Shrink module and Fringe Killer with no success, it did not reduce the fuzzy halo. I'm sure that I'm missing an obvious fix, but what?

[happy-kat]

what are you using to image with, might that be chromatic aberration?

[1loosetooth]

Hi, I'm shooting with a C8 SCT and Nikon DLSR, I've attached a picture that demonstrates the issue.

[Mike in Rancho]

Nice looking image! Especially considering the focal length you must be at for this field of view.

I'm not sure I see anything that unreasonable.

Big and bright stars make fuzzy halos. And at this scale, those are the biggest and brightest of them. Often blue, but sometimes white or orange.

I do notice many are a bit misshapen, which I would attribute to something in the optics. And there's a bit of ringing, perhaps from use of deconvolution?

The fuzziness of the halo can sometimes be smoothed out by the settings you choose in denoise, as well as SS module - particularly in 1.7 where the gamma is 0.50, or if lowered to that in 1.8.

Shrink module settings can also be variously used for some deringing (if not otherwise handled in deconv), reducing the core and/or halo some, color taming, or yet again smoothing out the fuzziness of said halo.

Mostly though, for me, bright halos are just a part of this, and I'll try to make sure they at least have a nice bright star look to them when all is said and done.

Now, if you think you are really losing control of a star right from the get go in AutoDev and you think you shouldn't be, you might try including one of those bright stars within the ROI and see if that keeps it from being a bigger ball of fuzz? It's also possible that the gamma and shadow linearity sliders might help with that if you aren't including the star in the ROI, though off the top of my head and I can't recall just which one or which way to slide them.

[1loosetooth]

Thanks, to bring closure, I used a combination of the Repair and Heal modules along with masking the fuzzy blur with fill lighter pixels and unmasking the star with lasso, one star at a time. There were only a few stars that needed this attention. I need to learn to be more creative with the mask function as Startools appears to have the ability to correct most if not all photo anomalies.

[Mike in Rancho]

Well, if you like it and it's the results you were aiming for, cool deal.

I admit I am more partial to image 1 though, but I am a fan of stars and star color.

You also have some ringing artifacts around the newly-white stars too. You might be able to clean that up by using Shrink with the affected stars selected, mask grown as needed, and use no iterations of shrinking but do use deringing to whatever pixels are needed. Just a thought.