Some sessions give you diamonds. Others, merely gravel! The ups and downs of milky way astrophotography!

 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

 Below is the updated, slightly refined workflow I used for this session.

 

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.

 

Lots to be please about in the landscape bit - most of it is well lit and in focus. 

The blur of breaking waves is nice. 

Issues? The stark transition line at horizon; the mismatching tone and colouring between landscape and sky. The sky is too blue and not well defined. 

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.

 

Version two - the landscape is too dark now! 

This post editing malarkey is quite challenging to grasp! 

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

1. 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.
2. Invert the selection
   Now the landscape is selected instead of the sky.
3. Create a mask
   With the landscape layer highlighted, click the Mask Layer icon.
   The sky should now disappear.
4. Deselect
5. Add the sky image
   Paste your sky TIFF into the document.
6. Move the sky layer below the landscape layer
   This places the sky “behind” the masked foreground.
7. 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.

 

This one is my favourite - the landscape was taken at midnight. The sky done afterwards with fewer tracked shots at a lower ISO and shutter speed. 

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