New to my blog? You can drop in here first to learn more about me and the blog: https://undersouthwestskies.blogspot.com/p/welcome-to-my-astronomy-and.html
As the blog grows, I want it to stay easy to navigate. To help with that, I’ve put together a simple guide that explains how everything is arranged and how to find things quickly:
- Want to Find Something Quickly on My Blog? https://undersouthwestskies.blogspot.com/2025/12/want-to-find-something-quickly-on-my.html
You’ll also see labels, categories, and series developing over time so you can follow particular themes - whether that’s equipment, observing sessions, learning logs, or location-based posts. Anyway, welcome and enjoy. I hope ytou find something useful. Steve
Milky Way Editing Workflow: What I Managed to Salvage From a Tough Night at Durdle Door
“Not every Milky Way session gives you diamonds —
sometimes you come home with gravel. Last week at Durdle Door was one of those
nights! Here, in today’s post, I show how I salvaged the data, blended the sky
and landscape in Affinity Photo, and squeezed something usable out of a tough
session. Clear skies… eventually!”
Last week I returned to Durdle Door for my second
Milky Way session of 2026 — and if you’ve read the trip report, you’ll know it
was a night that fought me every step of the way. Between wind, moon glow, and
a restless tripod, the data I brought home was… well, let’s call it “character‑building.”
Sometimes astrophotography hands you diamonds; sometimes it hands you gravel.
This time, I came home with a bucket of gravel.
Still, even a difficult session has value. You learn, you
adapt, and you squeeze every last drop out of the data you did manage to
capture. That’s what this post is about: how I processed the images,
what worked, and how I blended the sky and landscape using Affinity Photo.
Read the full story of my Durdle Door Milky Way shoot
here: My Second Milky Way Session of 2026 at Durdle Door
https://undersouthwestskies.blogspot.com/2026/05/my-second-milky-way-session-of-2026.html
And if you want the detailed version of my milky way editing
workflow, this earlier guide covers the foundations: For the full breakdown
of my workflow, see my Milky Way Editing Tutorial (Affinity Photo +
Sequator).
https://undersouthwestskies.blogspot.com/2025/12/editing-tutorial-guide-to-how-i-post.html
My Milky Way Editing Workflow (2026 Update)
1. Stacking the Sky Images — Twice
For each night, I created two separate stacks:
- one
in Sequator
- one
in Affinity Photo
I always do this. Some nights Sequator produces a cleaner,
more natural result; other nights Affinity Photo pulls ahead. It’s a bit like
developing film in two different darkrooms — you never know which one will coax
out the best detail until you compare them side by side.
Each program produced one stacked sky image for Night One
and one for Night Two.
2. Preparing the Landscape Images
I selected a handful of blue hour and midnight
hour landscape shots and opened them in Affinity Photo’s Develop Persona
for basic RAW adjustments.
Key steps:
- neutralised
the pink cast caused by my astro‑modified camera
- applied
the same colour‑correction method described in my earlier workflow post
- exported
each landscape frame as a TIFF
These TIFFs become the “foreground plates” for the final
composite.
3. Preparing the Stacked Sky Images
The stacked skies went through the same initial treatment:
- colour‑neutralising
the astro‑mod magenta tint
- adjusting
white balance for a clean, natural starting point
- exporting
as TIFFs ready for blending
At this stage, both sky and landscape images are “pre‑balanced”
so they play nicely together later.
How I Replace the Sky in Affinity Photo
This is the part people ask me about most often, so here’s
the exact process I use — clean, repeatable, and reliable-ish – if you have
some basic photo processing skills.
Step‑by‑step sky replacement workflow
- Select
the sky
Use the Select Brush Tool to paint over the sky area.
Click Refine and brush along the horizon to improve the transition. - Invert
the selection
Now the landscape is selected instead of the sky. - Create
a mask
With the landscape layer highlighted, click the Mask Layer icon.
The sky should now disappear. - Deselect
- Add
the sky image
Paste your sky TIFF into the document. - Move
the sky layer below the landscape layer
This places the sky “behind” the masked foreground. - Position
the sky
Use the Move Tool.
I temporarily set the sky layer to 75% opacity so I can align it precisely.
Blending the Horizon for Realism
This is where the magic happens — the difference between a
believable composite and one that looks like two photos glued together.
Softening the transition
- Select
the landscape mask
- Use
a soft black brush at 10–20% opacity
- Gently
paint along the horizon to soften the edge
- If
the transition is still too harsh, apply a 1–3px Gaussian Blur to
the mask
As my wife, who makes her own clothes, would say “Think
of this step as feathering two pieces of fabric together until the seam
disappears.”
Matching Colour and Light Between Sky and Foreground
Adjusting the sky
On the sky layer, I typically apply:
- Recolour
Adjustment (warmer or cooler depending on the scene)
- Curves
Adjustment (to brighten or darken specific areas)
- HSL
Adjustment (to reduce saturation if needed)
For the Milky Way:
- background
sky → slightly cooler, bluer hue
- Milky
Way core → a touch more magenta
Right‑click each adjustment and choose Mask to Below
so it only affects the sky.
I often darken the sky slightly near the horizon — a
personal preference, but it adds depth and realism.
Adjusting the landscape
The goal is to make the foreground feel like it belongs
under that sky.
Typical adjustments:
- Curves
to darken or cool the landscape
- HSL
if colours feel too warm or saturated
- Mask
to Below so adjustments apply only to the landscape layer
Finally, I may feather the horizon again with a soft black
brush at 10–20% opacity, building up the blend gradually until it feels
natural.
Final Thoughts
This wasn’t the Milky Way session I hoped for — far from it.
But even when the data isn’t great, the workflow still teaches you something.
Every failed frame is a stepping stone to the next successful night, and Durdle
Door will definitely see me again when the conditions are kinder.
If you’ve got tips, tricks, or your own approach to blending
sky and landscape, drop them in the comments. I always credit contributors in
future updates and love learning from other people.
Clear skies, stay safe, and keep looking up
— Steve
- Beginner’s
Guide: How to Photograph the Milky Way in the UK https://undersouthwestskies.blogspot.com/2025/02/beginners-guide-to-taking-your-first.html
- How to plan for a milky way photography session: https://undersouthwestskies.blogspot.com/2025/08/a-beginners-guide-to-post-editing-your.html
