M13 Hercules Globular Cluster

[Menno555]

I just did see that Oopfan (Brian) also made a M13 posting. Here is my version from 2 nights back (plus data from 2021).

Capturing and processing globular clusters really is like a different kind of discipline in comparison to galaxies or nebulae. I used 30 second exposures and with my f/10 scope, that's right around the "switching point" where drift becomes visible but where the pixels are not "full".
And with processing it's a balancing act between not using (or almost not) noise removal because the small faint stars disappear but at the same time stretching rather aggressively to show those same stars. And of course not to blow out the core.

M13-sm.jpg (499.15 KiB) Viewed 799 times

Bortle 6/7
Meade LX200 8" f/10 ACF OTA
Ioptron CEM25EC mount
Baader IR/UV Cut filter
Optolong L-Pro filter
Zwo ASI071MC Pro camera

Captured with SharpCap Pro @ -10 Celsius / White balance R50 B50
Baader IR/UV Cut: 50 x 30sec / Gain 90 / Offset 10
Optolong L-Pro: 100 x 30sec / Gain 90 / Offset 20
Per set: 20 x darks, 50 x flats and 50 x darkflats

Stacked with DeepSkyStacker
All in 1 stack

Processed with Siril and Photoshop
Siril: Background Extraction, Histogram, Crop
Photoshop: Curves, Levels, Camera Raw Filter (blacks, white balance, shadows, color saturation, clarity, sharpening, noise reduction)

[oopfan]

Really great, Menno!

I totally need a new kit. Big aperture is a must.

Brian

[carlomuccini]

Hi

Congratulations for the beautiful photo

I saw that you used two filters: IR cut and Lpro
How did you balance the final colors?

Carlo

[Menno555]

Really great, Menno!

I totally need a new kit. Big aperture is a must.

Brian

Thanks Brian!
The 8" definitely is a plus, yes

Hi

Congratulations for the beautiful photo

I saw that you used two filters: IR cut and Lpro
How did you balance the final colors?

Carlo

Thank you Carlo
I first tried to stack and process the sets separately, merging them in Photoshop. But that result was not to my satisfaction.
Stacking both sets in one go gave better results in this case. The L-Pro filter gave more red dominant results and the UV/IR Cut was more dominant in blue.
That total stack I processed in Photoshop and the final color balance was done with the White Balance (Temperature and Tint) in the Camera RAW Filter. First roughly so that the histogram there did match and then finetuning so that the background was around equal in it's RGB values. And then strengthen the lot

Menno