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Data from FaanBE on reddit askastrophotography:
https://reddit.com/r/AskAstrophotography/comments/1napads/best_way_to_proces_osc_dual_narrowband_siril/
The image is is copyright FaanBE.

Images made with a stock Canon 90D, 70-200 mm f/2.8 L IS lens at 130 mm, f/3.5/ Aperture = 130 / 3.5 = 37 mm diameter. Total image: 44. Exposure time: 1 minute each, for a total of 44 minutes.

Raw convert in photoshop CS6 with lens profile (include flat field). Raw converter settings:

temperature = 7000
tint = +150

exposure = -0.45

blacks +15

################

Sharpening:
amount = 25
radius = 1.0
detail = 25
masking = 0

Noise reduction:
luminance = 33
luminance detail = 50
luminance contrast = 0
color = 25
color detail = 50

############

lens profile selected

Remove chromatic aberration

defringe:

purple amount = 2
purple hue = 30 / 74

green amount = 1
green hue = 32 / 68

No darks, no flats, no bias.

Temperature and tint determined by making a star with solar B-V color index close to the Sun. Star identified in the Figure 1, below.

Figure 1. A "white" reference star.

Stacked in DSS

Color preserving stretch:

rnc-color-stretch ../dss/veil-nebula-dss-stack.tif -rootpower 10 -rootpower2 4 -skylevelfactor 0.01 -histogrambox1 2238 2167 2556 2565 -scurve1 -display -obase veil-nebula-90d-dual-narrowband-130mm_MG_9170-213-dss-rs10,4,slf0.01,hbx1,sc1

Cropped result after some curves adjustment to make the background more uniform:

Figure 2. Final result, 1/2 full resolution.

Reduce star size:

Figure 3. Star size reduced using ImagesPlus stars: 0.8

Resources:

Astrophotography Made Simple Details of color calibration: Sensor Calibration and Color

September 12, 2025