Help with Color Correction


I just picked up a non-modified Canon 6D.

Below is a 1h 36m shot of the milky way, ISO 1600 with 120sec subs.
I’m using Siril to process the image.
The question…

Why are the H-alpha regions, Lagoon, Trifid and Omega nebulae showing up basically white? Why aren’t these more red?

I believe I have the color balance correct. I tried both “photometric color calibration” on M20 and or M8 and manual correction using a selection of blank sky. I also tried “remove green noise”

I understand that an astro-modified camera will improve the red response.

I’ve used the Arcsin stretch in Siril to preserve the colors while stretching so that isn’t it.

It is with a Canon 70-200mm at 200mm and f/2.8 with a B&W F-Pro protective filter.

The thoughput at H-Alpha on this filter is at least 95%

Any ideas?



The answer is in your message.

As you said, you will have a lack of red. So it is difficult for the color calibration tool to get something really red.