Beginner’s Guide to Post-Editing a Stacked Comet Image in Affinity Photo V2

 Beginner’s Guide to Post-Editing a Stacked Comet Image in Affinity Photo V2

With the free of Affinity Photo 3, I know many astrophotographers are considering the switch across from Photoshop. I have been using Affinity Photo for two years now and this is my workflow for processing a comet image.

Tools Used:

·       Develop Persona (for RAW files)

·       Photo Persona (main editing workspace)

·       Layers, Masks, Curves, Levels, HSL, and Noise Reduction filters

If you want to know how to capture a comet image - these previous posts may help: 

https://undersouthwestskies.blogspot.com/2025/10/a-beginners-guide-to-photographing.html

https://undersouthwestskies.blogspot.com/2025/11/imaging-session-chasing-comet-lemmon.html 

https://undersouthwestskies.blogspot.com/2025/11/beginner-tutorial-how-to-stack-comet.html

 

Workflow

If working from a single RAW file:

Start at Step 1 (Develop Persona).

If importing a stacked FITS/TIFF image:

Open the file directly into Photo Persona, but still follow the adjustments from Step 2 onward.

 

1. Prepare Your Image in the Develop Persona (RAW files only)

These steps set a clean starting point before moving to the main editor.

• Exposure: Pull back highlights if the comet nucleus looks blown out.
• Black point: Increase slightly to deepen the sky background.
• Contrast & Clarity: Keep very low — high values exaggerate noise.
• White Balance: Neutral or slightly cool for a natural comet colour.
• Lens Corrections: Enable chromatic aberration and vignetting corrections.

Click “Develop” to enter the Photo Persona.

 

2. Clean Up the Background & Frame the Image

This stage sets your sky background and composition before isolating the comet.

a. Crop & Rotate

Straighten the frame and position the comet creatively (e.g., rule of thirds or aligning the tail diagonally).

b. Duplicate the Base Layer

Right-click → Duplicate.
Having a backup layer is always useful.

c. Remove Gradients / Light Pollution

Choose one approach:

• Manual tools:
  Use the Inpainting Brush or Clone Tool to smooth bright areas near the horizon.
• Curves + Mask method:
• Add a Curves Adjustment Layer
• Invert its mask
• Paint white on the mask where gradients occur
• Gently darken those regions
• External tool:
  Software like GraXpert often produces excellent gradient removal results, then you re-import the cleaned image into Affinity.

This gives you a clean sky to work with before enhancing the comet.

 

3. Isolate and Enhance the Comet

This step ensures that adjustments to the comet don’t accidentally affect the stars or sky.

a. Select the Comet

Use the Selection Brush Tool or Freehand/Pen Tool to outline the comet and tail.

b. Feather the Selection

About 10–30 px, depending on image resolution.

c. Create a Masked Layer

Right-click → New Layer with Mask.
Now you have a specific “Comet Layer” for targeted editing.

d. Enhance the Comet

• Curves: Lift midtones and highlights slightly to brighten the tail and nucleus.
• HSL:
• Slight saturation boost (5–10%)
• Subtle hue shifts if you want to emphasise green/blue tones in the coma
• Detail Enhancement:
  Use Unsharp Mask or the Clarity filter, gently:
• Radius: 1–2 px
• Amount: ≤ 30%

This should bring out tail structure without creating halos.

 

Comet Lemmon october 2025

Images snatched between cloud breaks 

4. Control Stars & Background

Comets often benefit from reducing the prominence of surrounding stars.

Option A — Using Plugins

If you have the James Ritson astrophotography macros/plugins for Affinity (or similar tools), apply the star-reduction macro here.

Option B — Manual Star Softening

A simple technique: 

1. Duplicate your background layer.
2. Apply Gaussian Blur (≈ 3–5 px).
3. Change the layer’s Blend Mode to Darken or Soft Light.
4. Mask out the comet so it remains bright.

This subtly reduces star intensity without removing them.

Optional: Boost Star Colour

Use HSL or Selective Colour, applied through a mask targeting only the star field.
Increase saturation very gently for natural, pleasing star colours.

 

5. Final Colour & Contrast Refinements

These global adjustments tie the whole image together.

• Curves: Add a subtle S-curve to improve overall contrast.
• HSL or Selective Colour:
  Adjust the sky tone — aim for a natural, slightly cool deep grey/blue-grey rather than pure black.
• Levels:
  Bring the black point inward carefully. Avoid clipping faint comet tails or dust structures.

 

6. Noise Reduction & Final Polish

Noise typically increases after gradient removal and enhancement steps, so save this for last.

1. Merge a copy of the visible layers (Right-click → Merge Visible).
2. Apply Reduce Noise (Filters → Noise → Reduce Noise):
• Luminance: ~30–50%
• Colour: ~20–40%
• Preserve Details: ON

You can also use a mask to apply noise reduction only to the background, keeping the comet sharp.

 

A second version of my Comet Lemmon image 

7. Exporting Your Final Image

Choose output format based on purpose:

• TIFF (16-bit): Best for scientific, archival, or further processing.
• PNG or JPEG: Ideal for sharing online (JPEG quality ~95%).
• Use sRGB profile for web posting.

 

Optional Advanced Techniques

• Comet/Star Combination:
  Blend a comet-tracked stack with a star-tracked stack using Lighten or Screen blend modes for the best of both worlds.
• Affinity Astrophotography Stack (V2.4+):
  Affinity now supports astrophotography stacking natively, including star alignment and median stacking — useful for producing a cleaner starting point before editing.

 

Final Thoughts

Affinity Photo V2 is a powerful, affordable tool for comet processing, and once you get comfortable with masking and adjustment layers, you’ll find it capable of professional-quality results.
Working slowly, keeping edits subtle, and masking carefully will help your comet images look clean, natural, and visually striking — perfect for sharing or printing.

Of course, as a beginner myself, Affinity Photo is still something I have to master. Masking is my Achilles heel – rather frustratingly!

As always, do you have a different work flow? What do you do differently? What additional tips would you add in here? Drop us your tips, thoughts, observations in the box below. 

Clear skies and take care out there, and as always, have plenty of fun! 

Steve 

Equipment review: Samyang 135mm f/2 (Manual Focus) — My Go-To Wide-Field Astro Lens

 First visit to this astronomy/astrophotography blog? Well, firstly a warm welcome to you and thanks for stopping by. If you want to find out more about me and this blog, why not visit my introductory page at https://undersouthwestskies.blogspot.com/2025/01/welcome-to-my-new-astronomyastrophotogr.html  You can also browse other posts by using the search bar or the blog post list on the right hand side and I'd really like to hear from you via the comment boxes. Drop me a tip, an observation or a question. Take care and clear skies to you.  Steve 

Samyang 135mm f/2 (Manual Focus) — My Go-To Wide-Field Astro Lens

If you love photographing the night sky but don’t want to remortgage your house to do it, then the Samyang 135mm f/2 could be your new favourite piece of glass. I like to keep my setup simple, reliable, and travel-friendly and I’ve been using this lens for more than two years, teamed with my Canon 800D; it’s my go-to companion for wide-field astrophotography whether it be to frame a nebula or sweep across the Milky way without lugging a telescope around.  

After two years of late nights, frosty fingers, and countless star fields, I thought it was time to share my thoughts. What makes this lens such a hit among astrophotographers? How does it perform? What are its strengths and pitfalls? And, what are the trade-offs you should know before you buy? Let’s find out.

In this review, I’ll:

• Walk through the key features
• Highlight the strengths
• Weigh up the downsides
• And wrap up with my honest verdict

My lightweight, portable wide-field astro rig incorporating the samyang 135mm f/2 lens with my canon 800D DSLR 

Overview

The Samyang 135mm f/2 is a bit of a cult classic in astrophotography circles — a manual-focus, full-frame compatible prime lens that delivers serious optical performance without burning a hole in your wallet. It’s available in several mounts (Canon EF, Nikon F, Sony E, and more), and photographers often praise it for its sharpness and contrast at a surprisingly modest price.

Think of it as the astrophotography world’s version of a dependable old telescope — it doesn’t boast flashy electronics or fancy features, but what it does offer is clarity, consistency, and a ton of light-gathering power.

At f/2, it’s a light vacuum, pulling in photons like a cosmic magnet. Even at f/2.8, stars in the corners remain crisp and clean, with minimal chromatic aberration or distortion. For me, it’s become a workhorse lens that simply delivers, night after night.

Why It Shines for Astrophotography

Here’s what I think makes the Samyang 135mm such a gem for capturing the night sky:

1. A fast f/2 aperture — a real light bucket.
Speed is everything in astrophotography. The faster the lens, the less time you need to collect light — and that means fewer tracking errors, shorter subs, and sharper stars.

2. Excellent corner-to-corner sharpness.
Even wide open, stars stay tight and well-defined all the way to the edges. Many lenses struggle with soft or warped corners, but this one keeps its composure beautifully.

3. Great value for money.
Compared to astrographs or premium telescopes with similar optical performance, the Samyang 135mm is an absolute bargain. You get premium-level sharpness at a fraction of the price — ideal for beginners or anyone building a portable setup.

4. Manual focus — an advantage, not a drawback.
In astrophotography, autofocus is about as useful as sunglasses at midnight. Manual focus gives you full control, and with a simple Bahtinov mask (you can easily 3D-print or order one online), you can achieve razor-sharp stars every time.

5. Plenty of compatible accessories.
This lens is a tinkerer's dream. You can attach support rings, dovetails, red-dot finders, guide scopes, ASIAir units — even a ZWO EAF focuser if you want to automate your setup. These can be 3D printed – if you are lucky enough to own one – or easily purchased off various shopping websites

6. Perfectly balanced focal length.
At 135mm, you’re right in that sweet spot between wide-field and close-up imaging. Large nebulae, Milky Way segments, star fields — it handles them all beautifully. On crop-sensor cameras, the extra reach (around 200mm equivalent) makes it even more versatile.

7. Impressively low chromatic aberration.
Colour fringing on stars is minimal — a big win if you’re after clean, natural-looking results, especially in narrowband imaging.

8. Portable and travel-friendly.
Pair it with a small star tracker like the Sky-Watcher Star Adventurer, and you’ve got a grab-and-go setup that can fit in a backpack. No observatory required — just clear skies and a bit of patience.

9. When using a cooled astro camera (mono/colour) with filter wheel etc, the Samyang 135mm f/2 can serve as a fast, relatively “short‐telescope” field of view—great for large nebulae, wide star fields, Milky Way segments in narrowband or broadband. Because many astro-cameras have large sensors, the good corner performance is very useful.

copyright astropical space

Disadvantages (a.k.a. “The Fine Print”)

No lens is perfect — and the Samyang 135mm does have a few quirks worth knowing. Think of these not as deal-breakers, but as “lessons from the field.”

1. Vignetting at wide apertures.
At f/2, corners can lose up to 40% brightness. It’s nothing a good set of flat frames (or stopping down to f/2.8) can’t fix, but it’s worth planning for.

2. Sample variation.
Quality control can be hit or miss. Some copies are pin-sharp, others have slight decentring or coma issues. Buy from a reputable dealer with a solid return policy.

3. Infinity focus quirks.
When used with astro cameras and adaptors, the lens doesn’t always hit true infinity focus right at the mark (particularly when using M42/T2 adapters, it seems). You may need to experiment a little with spacers or back-focus distance.

4. No weather sealing or stabilisation.
Not a huge issue for astrophotography, but if you’re shooting on cold or damp nights, dew control is essential. A lens heater or dew strap is your friend here.

5. Focusing precision required.
At f/2, the depth of field is razor-thin. Even a hair off perfect focus can soften your stars. Take your time, use Live View zoom, or better yet — a Bahtinov mask.

6. Middle-ground focal length.
Some users find 135mm to be neither wide enough for sweeping Milky Way shots nor long enough for small galaxies. Personally, I find it a perfect “in-between” — but it depends on your targets.

7. Back-focus spacing issues (for astro cameras).
When used with filter drawers or adaptors, incorrect spacing can throw off sharpness or infinity focus. It’s worth double-checking your measurements — the devil really is in the millimetres.

8. Heavier than you’d expect.
At first glance, it looks compact, but it’s got a bit of heft to it. Still, when you balance it properly on a tracker, it’s more than manageable.

My Verdict

After two years of use, I can confidently say, that based on personal experiences, the Samyang 135mm f/2 must be one of the best bang-for-your-buck astrophotography lenses out there. It’s sharp, fast, and remarkably capable for its price. A compelling option for beginners on a limited budget who want a relatively fast, high-quality lens.

Sure, it asks for a little patience — careful focusing, calibration flats, and the occasional bit of back-focus tinkering. But if you’re willing to put in that small effort, it rewards you with breathtaking wide-field images.

Copyright Stellar Discovery 

To summarise:

• Highly recommended if you’re using a DSLR or mirrorless camera and are ready to get serious about wide-field astrophotography.
• Excellent for astro-camera users, provided you dial in your adapter spacing and calibration.
• Less ideal if you need autofocus, weather sealing, or prefer ultra-wide or ultra-long focal lengths.

In short, this lens is like an honest, hard-working friend — it doesn’t boast, but it consistently delivers. It’s built for those who value results over bells and whistles.

What about you? Have you used the Samyang 135mm f/2 in your setup? What camera have you paired it with — and what celestial wonders have you captured? I’d love to hear your experiences in the comments below.

Until next time — clear skies, steady mounts, and may your focus always hit infinity.

— Steve

If you are seeking a more detailed review of the lens then try this one  - I take no responsibility for the website or any links from it - but I did find it an informative review - https://stellardiscovery.com/samyang-135mm-f-2-widefield-astrophotography/

Beginner tutorial – how to stack comet images in Deep Sky Stacker (my work flow)

First visit to this astronomy/astrophotography blog? Well, firstly a warm welcome to you and thanks for stopping by. After reading this post, if you want to find out more about me and this blog, why not visit my introductory page at https://undersouthwestskies.blogspot.com/2025/01/welcome-to-my-new-astronomyastrophotogr.html  You can also browse other posts by using the search bar or the blog post list on the right hand side and I'd really like to hear from you via the comment boxes. Drop me a tip, an observation or a question. Take care and clear skies to you.  Steve 

 Beginner tutorial – how to stack comet images in Deep Sky Stacker (my work flow)

Ever wondered how to turn your series of faint comet frames into one crisp, detailed image? In today’s post. I’ll walk you through my step-by-step work flow for stacking comet images in Deep Sky Stacker DSS) – a free, powerful tool that’s perfect for astrophotographers who want to capture the beauty of a comet without those distracting star trails.  

In summary, the work flow order goes like this:

1.      Open picture frames

2.      Then for each image use the green comet image to select the comet’s nucleus – saving the position for every frame

3.      Entering the stacking settings, choosing a comet stacking mode (Comet only, stars only, both)

4.      Starting the process of stacking

 

So, let’s dive straight into the more detailed work-flow.

Step 1: Register all images 

First, let’s get your light frames ready.

• Open Deep Sky Stacker and click ‘open picture files’
• Select all the comet frames you want to stack
• (Select all the bias, flats and dark frames you want to add in)
• Click ‘check all’ – and then choose ‘Register checked pictures’

·       In the pop-up window, make sure to:  –

o   check ‘register already registered pictures’

o   check ‘automatic detection of hot pixels’

o   DO NOT check ‘stack after registering’.

o   Then click ‘OK’ to start the registration process

This last step makes sure DSS knows exactly how to align and handle your images before we move on to the comet itself.

 

Step 2: Mark the comet’s nucleus in each image 

Now for the fun part — telling DSS where your comet is in each shot.

• Select the first image in your list
• Click the green comet icon on the right side of the screen
• hold down the Shift key and click directly on the comet's nucleus to mark its position. A pink circle should appear around it.
• Save the changes for that image. You can click ‘save all’ so DSS keeps track of the comet position across all selected frames OR
• Repeat this process for every light frame

This step can be a little repetitive, but it’s essential — it tells DSS how the comet moves across your frames, allowing it to align the comet while still handling the star background correctly.

Tip: If you’ve seen the tutorial “How to Stack and Process Comet Images with Deep Sky Stacker,” it shows a great visual example of this process. How to Stack and Process Comet Images with Deep Sky Stacker

 

Step 3: Stack the images

With everything marked, it  is time to stack your comet.

• Click ‘Stack checked pictures’.
• When dialogue box appears, choose ‘Stacking parameters’ appears
• go to the Comet tab and choose your desired stacking mode.
• "Stars" (comet trails)
• "Comet" (star trails) or
• "Stars + Comet" (both) – my go to choice  
• Click OK to start the stacking process. 
• If another pop-up window appears called ‘stacking steps’, keep the default settings and just click ‘OK’ again.

When DSS finishes, save your stacked image as a TIFF file, ready to edit in your favourite processing software — whether that’s Photoshop, Affinity Photo, PixInsight, or any other astrophotography editor.

Want to See It in Action?

If you prefer to follow along visually, these videos do a fantastic job of demonstrating how to select and use the comet stacking modes in DSS:

How to STACK Comet in Deep Sky Stacker - Beginners Astrophotography Tutorial

How to Stack Comet Images Without Star Trails in DeepSkyStacker

Final Thoughts

Stacking comet images in DSS might feel a bit technical at first, but once you’ve done it a couple of times, it becomes second nature. The reward is absolutely worth it — a clean, vibrant image that beautifully captures the motion and structure of your comet, without losing the stars in the background.

Give it a try with your next comet data set and watch your images transform! As always, if you have a tip or an observation about my work-flow, then drop me a comment so we can improve it for all and, it goes without saying, but I will anyway – stay safe, have fun and clear skies to you all

Steve

Whats happening in the night sky this month? November 2025

 First visit to this astronomy/astrophotography blog? Well, firstly a warm welcome to you and thanks for stopping by. After reading this post, if you want to find out more about me and this blog, why not visit my introductory page at https://undersouthwestskies.blogspot.com/2025/01/welcome-to-my-new-astronomyastrophotogr.html  You can also browse other posts by using the search bar or the blog post list on the right hand side and I'd really like to hear from you via the comment boxes. Drop me a tip, an observation or a question. Take care and clear skies to you.  Steve 

What’s happening in the Sky – November 2025

Date	Astronomy visual observing	Astrophotography
1/11	The Moon rising or waxing gibbous near Saturn is a nice sight south-west after dark. (Mag+0.4 Saturn 5.7 degrees from moon)  Mercury low in south-west skies.
2
3
4	Calisto's shadow transits Jupiter from 0701 to 1036. Jupiter rises 2055 - 2225
5	Full ‘Beaver’ Moon / “Supermoon”
6	6-10 Nov Early evening: check for the Pleiades cluster in Taurus (just above right of a low Moon maybe) and larger star fields; morning twilight: Venus rising low. Also - transit of Titan across Saturn 2033 - 0233 on 7/11
7	Ganymede eclipsed by Jupiter's shadow 0400
8		Comet 24p/Schaumasse crosses M44 Beehive cluster - capture with big apertures/bigger imaging rigs
9
10	71% waxing gibbous moon close to Jupiter 0600 as awn twilight brightens - both less that 4 degrees apart
11	Meteor showers: Taurids peaking. 60% moon near M44 Beehive Cluster. Saturn's tilt less than 0.5 degree - appearing virtually edge on till 8/12
12	With the last ¼ Moon waning and dark skies improving: Meteor activity (Taurids) may be seen after midnight.	go for faint constellations, try spotting the Milky Way band rising in north-east dark skies.
13		As moon subsides – good DSO’s for next twelve days include M45 Pleiades. M42 Orion,  M27 Dumbell nebula,
14	Titan occulted by Saturn 1848; reappearing 0035 on 15/11. Moon enters glancing partial eclipse by Saturn's shadow at 0125	Double Cluster (NGC 869 & 884) in Perseus – use narrowband filter; M33 Triangulum Galaxy
15	Saturn’s tilt apparent and it will continue reducing its tilt towards December
16
17	Leonids peaking. Radiant located in head of Leo the Lion, marked by sickle part of asterism. meteors around 15 per hour
18	Peak Leonids meteor shower around 17-18—best after midnight, look away from the Moon and horizon.	Dark skies good for deep sky for the next part of the month.Target the fainter DSO’s
19
20	Venus low in morning twilight; Saturn in evening; other planets may be visible with binoculars. New moon	Good 135mm targets for nights either side of new moon – IC1805 Heart nebula; NGC 1499 California Nebula;  NGC 13333 Molecular cloud reflection nebula (try long broadband filtered exposures)
21	21-25 Nov The evening sky centres on the richer winter constellations: Orion, Taurus, Gemini rising. Use binoculars/telescope to scan for clusters and nebulae. Uranus at opposition. Jupiter - 0105 - 0450 double shadow transit by Io and Callista's shadows
22	Titan transits Saturn 1852 - 0110 on 23/11
23
24
25	Shadow of Ganymede transits Jupiter 0208 – 0525. Actual moon transit between 0609 - 0929
26
27
28	1st ¼ moon
29	Saturn sits 28 Degrees s of 65% lit waxing gibbous moon
30	Titan occulted by Saturn 1722 - 2308