astrophotography-image-stacking.md

Astrophotography Image Stacking on Mac OS

This is a very quick tutorial on how I do my astrophotography image stacking on Mac OS. The document is mostly for myself to remember how to do it, but feel free to add your comments and improvements.

I knew some of the rules described in the following, but never really remembered them exactly. So here it is, my little reminder on how to stack astro photos.

Requirements

• Starry Ladscape Stacker
• Photo editing software, I do use Lightroom CC

How To

TL;DR

• max brightness in edit
• reduce contrast in edit
• leave lens profile correction on in edit
• remove noise reduction in edit
• export as TIFF in sRGB color mode

Capture Images

• Expose images to the right (ettr)
• "At least 10, probably not more than 40 images should be captured." [^sls-req]
• "All light frames and dark frames should have identical exposure settings (duration, aperture, ISO, focus). (Aperture and focus are irrelevant to dark frames and are ignored for dark frames)." [^sls-req]
• "The maximum time from capturing the first frame to capturing the last frame is 120 minutes. Less than 30 minutes is strongly recommended." [^sls-req]

Editing

• Switch white balance from Auto to Custom ("in Lightroom, if the white balance is set to “automatic” and you “sync” the settings across all of the images, the “automatic” setting is copied, not the specific temperature and tint.") [^sls-prep]

• "Reduce contrast in order to not "losing details either in the dark areas or in the highlights during stacking" [^sls-prep]

• "Turn off sharpening and noise reduction" [^sls-prep]

• "Apply lens chromatic aberration corrections if you want—Turn off all other lens corrections; in particular, lens distortion correction must be turned off." [^sls-prep]

• "Your primary goal at this point is adjust the tonal range of the images so that not too many stars are blown out and the darker areas are a bit brighter than you want them in the final image" [^sls-prep]

• "In general, the changes you can make during RAW conversion are:

  • adjust exposure
  • adjust contrast
  • adjust white balance
  • turn on chromatic aberration correction
  • apply a little noise reduction (a little, not a lot)" [^sls-prep]

There is also the recommendation to

• "Turn off lens distortion correction" [^sls-req] I tested both versions and don't know how to apply the correction later, so I leave it on.

Export

• Export as TIFF using sRGB color mode

Stacking

Stacking is not captured as part of this tutorial, but explained in full depth here

Known Problems

• "Clouds are a problem because they typically move quite quickly. There is no good way to deal with them—they will be blurred in the final result" [^sls-kp]

Different Frames

• "Light frames. These are your normal exposures." [^sls-proc]
• "Dark frames. These are images captured with the lens cap on. They are used to reduce fixed pattern noise." [^sls-proc]

Sources

1. [^sls-req] https://sites.google.com/site/starrylandscapestacker/restrictions-and-requirements-version-1-9?authuser=0
2. [^sls-prep] https://sites.google.com/site/starrylandscapestacker/preparing-images-for-starry-landscape-stacker-version-1-9?authuser=0
3. [^sls-proc] https://sites.google.com/site/starrylandscapestacker/processing-images-with-starry-landscape-stacker-version-1-9?authuser=0:
4. [^sls-kp] https://sites.google.com/site/starrylandscapestacker/shooting-starry-landscapes-for-version-1-9?authuser=0

See Also

• StarryLandscapeTracker Website

Example

The following edited picture is taken in Sweden Mårdselforsens.

• ISO 8000
• Sony 20mm F1.8 at F2.2
• 13.0 sec with Sony A7iii

This is the stacked and edited version (29 images in total):

• You can see less noise in the sky when zooming in, but the original version is already pretty good.

DSC08344.jpg

Mårdselforsens-Max Brightness-srgb-lens correction-10000-Min Horizon Noise.jpg