Night Sky Shooting / Astrophotography on X-T2 : ETTR? ISO 1600?

Sebastien Guyader wrote:

I've been playing around with Sequator, and I thought I'd share what seems to be the a workflow for the cleanest results.

1) Capture: set the camera to Raw, ISO to 800-3200, shutter speed 15-30sec (ISO and shutter speed will depend on the focal length and maximum aperture of your lens).

2) Raw processing: a minimal processing in a good raw converter is helpful. I use Rawtherapee, which allows me to apply white balance (important to me), vignetting and chromatic aberration and choosing the demosaicing algorithm, and to output linear 16-bit TIFF files (recommended input types for Sequator).

3) Aligning and stacking in Sequator:

• Composition: Align stars, Select best pixels (and if needed, Freeze ground)
• Reduce light pollution: Uneven
• Enhance star light: On
• Color space: Linear
• Output: uncompressed tiff

4) Postprocessing: I use Rawtherapee again for exposure compensation (to recover brightness) and final tuning using Lab adjustments (L* curve, chromaticity, fine tuning f color balance with a* or b* curve).

Below is a result I obtained form aligning and stacking 11 exposures (23mm @f/1.6, 15sec., ISO 2000) + 2 dark (noise) frames.

The result is much nicer to me than what I obtained using Siril for aligning and stacking (results I have posted some time ago here: https://www.dpreview.com/forums/post/61698294).

Long delay in posting a response but I was learning some PS techniques on top of what I was used to in LR.

I used Sequator and ran it in a VM on my mac to stack 9 images. I don't think I can ever go back to single shot photos!

Thanks for your guides and tips.

I found the Light Pollution Reduction in Sequator to be distracting or useless at levels 1 2 or 3. At level 4 and 5 (highest level), it was able to reduce any of the sky glow that resulted from stacking.

Here is a stack of 9 images. ISO 1600. 14mm. f2.8. 25 seconds (should have really been 20-23 seconds but I fudged the exposure time).