An almost 'end of year one' blog review

 If you are new to this blog and want to learn more about it, then firstly, welcome, and secondly why not start here at https://undersouthwestskies.blogspot.com/2025/01/welcome-to-my-new-astronomyastrophotogr.html

A 'cheating' composite photo

A separate foreground shot of our motorhome Bryony, recently out at Weymouth

A se[arate 'stacked' sky shot of  the Orion area which has been cropped and then blended with the original foreground shot. 

I just wanted you to see where I am slowly progressing to on my astrophotography/astronomy learning journey. 

An almost one-year review of the blog

I’ve conducted a brief review of my blog based on feedback from people who have visited it, an analysis by Chat GPT (I just wanted to try it out, having never used it before) and the patient ‘critical friend’ thinking that always comes from my wife.

I’ll just focus on the areas I want to improve over the forthcoming year for now, but if you want to read about my original aims for this blog then you can find them here at https://undersouthwestskies.blogspot.com/2025/01/what-is-aim-and-purpose-of-my-new.html

Some possible blog improvement areas for 2026 could be: 

1.      Posts about acquisition of data and use of equipment are sound but I need to improve the clarity, depth, and readability of ‘post-editing’ tutorials. I also need to include more ‘before/after’ comparison images, explaining step-by-step what I did to get the improvements

2.      Whilst some of my posts are more narrative and less structured, which is fine, I need to include more consistent elements to improve usability for myself and readers e.g. ‘summary of key points’, ‘what I’d do differently next time reviews’, ‘bonus tips’

3.      I need to better categorise posts through their titles to help me and others find their way around the blog e.g. ‘Beginner guides to ….’ ‘Gear reviews’ ‘Image capture’ etc

4.      Increasing interactive features like comment prompts, Q+A posts, regular reader submission pages, ‘How did your results go?’ etc to build up more of a community feel and participation rate

5.      Improve the SEO, discoverability and broader reach of the blog. Use more long-tail keywords (uur??) and more tags/categories. An old IT friend of mine said “make your older posts easier to find and navigate”. And a very social media savvy younger friend of mine, well she said “more visual thumbnails, more summaries for sharing on social media, get an Instagram page”. Gulp!

6.      Two young, world travelling, former students of mine suggested some more varied content could broaden blog interest e.g. “‘Astrophoto travel stories’, ‘Visiting dark-sky sites’” (they were in La Palma when they suggested this one!); “‘interview some fellow local astronomers and astrophotographers you know’” (another of their suggestions). ‘Challenges and setbacks’, ‘Quick tips’. Lots to think about going forward.  

7.      The whole ethos of the blog is based on ‘going on a learning journey of self-improvement’ in astrophotography and astronomy, so is there a way I can provide a visual ‘roadmap’ of the site which gets regularly updated e.g. “If you’re just starting, do X, then Y after you’ve mastered A, then move to B”. Would this move the blog from being more of a journal to more of a community resource?

This was my very first effort at imaging M42

Taken from Cathagena in southern Spain in 2023

So, almost a year in, lots to ponder. I think the blog is beginning to get a strong and authentic feel; one that shares a learning journey in a relatable way backed up by practical details, an honest approach and even, perhaps, a niche focus on ‘beginners’. We will see how it goes forward in 2026. I, for one, will still be out there trying to capture images of our amazing cosmos. I will still be grappling with developing some reasonable post-editing skills for both milky way landscapes and deep space objects. I’ll still be trying to learn and remember all the constellations. I’ll still be trying to learn the basics about the cosmos.

As always, drop me a ‘hello’, introduce yourself, tell us about your own learning journey in astronomy and/or astrophotography. Share an image you are pleased with. Pose some questions.

And, stay safe out there, clear skies and have enormous fun

Steve

An alternative view of the Rosette Nebula

Translated, that means "I did something wrong in post processing but I haven't yet worked out what or how"

Taken in 2023

A beginner's guide to photographing comets

 Detected first on 3^rd January 2025 by the Mount Lemmon Survey in Arizona, pre-discovery images from the Pan-STARRS survey date back to November 2024. Initially thought an asteroid, follow up observations revealed a condensed coma and faint tail. A long-period comet! With perihelion to the sun on 8^th November 2025, its inbound orbit period is around 1,350 years. And it comes from far out in the solar system, probably the outer Oort cloud. So, this is a relatively rare visit to the inner solar system. 

Like other comets, Lemmon has a s small rocky or icy body nucleus and a coma where solar heating has caused ice to sublimate, releasing dust and gases to form the fuzzy cloud around the nucleus. Its tail is broadly curved, of diffused ionised gas, bluish-green in appearance. As the comet gets closer to the sun, sublimation will increase, releasing more material and enhancing they coma and tail. Solar wind and radiation pressure, as it approaches the sun, will continue to ensure that its tail points away from the sun.

Lemmon, with its eccentric and retrograde orbit as it approaches the sun, is probably an early relic from the formation of the solar system and so it gives astronomers a chance to study material relatively unaltered since then. Like many of our visiting comets remaining unchanged as they arrive in our area of space, our sun heats them causing their icy nuclei to release gas and dust on tails and comas that reveal their composition. Studying this material allows us to learn what the early solar system was made of and how planets such as ours may have formed; delivering water and organic materials, the building blocks of life.  Lemmon carries fresh samples of this primordial material – its chemistry and dynamics is of critical interest.

I have only photographed one comet so far and I found it one of the most fun bits of astrophotography I have done so far on my learning journey. The comet changed its appearance every night I went after it and you can read more details here at this previous post:  https://undersouthwestskies.blogspot.com/2025/01/chasing-comet-c2023-tsuchinstan-atlas.html

The positives - I located the comet and managed to image it. The 'future learning'? Getting my editing skills better developed, particularly on white balance!! 😆

I used Sequator to stack several images. 

Clearly at the time I hadn't then discovered 'freeze' ground' and also 'stack for comet' options!

I'm aiming to do much better on Comet Lemmon - if the cloud ever actually clears away long enough in the south west 😱 

Anyway, moving on - what are my ‘beginner’s’ tips for capturing this latest cosmic visitor, if you haven't caught one before?

1.      21^st – 26^th October, when it makes its closest approach to earth and is at its brightest. It is also when there is no or only a faint presence of a new moon

2.      In the northern hemisphere, it will appear in the NW sky after sunset (30 – 90 minutes), once twilight has faded.

3.      Find a clear unobstructed horizon in a dark sky site away from light pollution and be aware that as the night progresses this comet will appear lower and lower in the sky;

4.      Look for the constellation Boötes and its bright star Arcturus as lead in points to its location.

5.      Because it is low on the horizon, try to include some foreground elements such as trees, hills, silhouettes to add context and scale

6.      Its tail will probably point roughly away from the sunset west direction and somewhat downward

7.      A wide to moderate focal length e.g. 24 – 70mm on a full frame camera, or a longer lens/telescope if you want detail in the coma and tail; try ISO 800 – 1600, aperture F/2.8 – F/4 on a fast lens. Exposures 10 – 30” depending on your focal length and whether your mount tracks or not. Shoot in RAW

8.      You could use a star tracker with a 200 – 500mm lens or small refractor for greater tail structure, again ISO 800 – 1600, 20 – 60” and aperture F/4 – F/5; if you are not using a tracker – take multiple 1 – 5” shots and stack them later in software but align on the comet rather than the stars or do both and merge, to keep the nucleus sharp. 

 

Because of its low elevation, there may be atmospheric issues to deal with:

1.      Pick nights with good transparency, if possible, to combat reduced contrast and also haze issues

2.      Try for a clear horizon line under such circumstances; avoid shooting towards sunset glow

3.      Mitigate atmospheric blur and tail motion by taking many short exposures

4.      Use a light pollution filter if you are under lights

 Composition and framing

My Achilles heel in astrophotography and I do try hard to improve it. For comets, which are highly dynamic subjects, composition matters; go for foreground elements such as trees and mountains in wide angled shots. Comets tails always point away from the sun, so that helps in framing the subject. Try to align the comet’s tail diagonally through the image for a dramatic composition. Look for potential juxtapositions – a bright star, a star cluster, an element of the milky way.

How do you do the post processing of your comet image?

1.      In the past I have combined stacks – one aligned on the stars and one aligned on the comet – blending them afterwards in something like deepskystacker or SIRIL - masking carefully to retain both sharp stars and a crisp comet nucleus.

          Combine the two images by blending them together in photoshop or affinity photo

2.      Levels and curves adjustments should aim to extract tail detail without blowing out the coma; use noise reduction but preserve the faint structure in the tail

3.      Colour balance, try to preserve the greenish hues

4.      Crop and sharpen GENTLY to bring out structure without over processing to get artefacts.

What about some beginner tips for shooting comets generally?

1.      Do your research using sources like Sky and Telescope, Sky at Night, etc to learn where and when the comet will appear.  More often than not, best times are when the comet is far from the sun in the sky – so typically visible before dawn or after dusk and when the moon is absent or below the horizon. Choose nights when it is higher in altitude above the horizon to avoid atmospheric haze and light pollution. Stellarium and Sky Safari apps will help you visualise where the comet will appear relative to your horizon, and constellations above.

2.      I have already mention equipment choices above but to build on that:

a.      A DSLR or mirrorless camera that shoots in RAW format. An astro-camera will get deep detail but isn’t essential.

b.      Lens or telescope? Tough question! Wide angle (14 – 50mm) will capture the comet in context with the landscape or milky way. Telephoto or small refractors (100 – 300mm etc – will reveal coma structure and tail detail

c.       A tracking mount such as a skywatcher star adventurer 2i (other brands are available) will allow you to go beyond the limit of shorter exposure times

d.      Tripod and intervalometer enable stability and no vibrations.

e.      Camera settings – how long is a piece of string? If I were doing a TRACKED image then I’d probably go somewhere with ISO 800 – 1600; F/2.8 to F/4 for wide angle lenses and F/4 to F/6 for telephotos; exposures 20 – 60” if tracked and 2 – 10 “if not.  White balance daylight or 4000K

f.        Multiple frames rather than one long exposure are better, it improves signal-to-noise ratio and allows stacking later.

g.       And always shooting in RAW

 

Photographing comets is a unique challenge that combines astrophotography, artistry and timing. Prepare well, bring the right equipment, master your post editing workflow and remember, you are capturing a rare celestial event and ancient cosmic visitor.

The Pacman nebula - first effort.

Just returned from a motorhome trip to Croatia. Whilst there I had the opportunity to image the nebula below.

My location was a forest clearing high in the Croatian mountains, near the border with Bosnia and Herzegovenia. No light pollution but a full moon, so I was using a light pollution filter. Clear big open skies. Very chilly but still, no wind.

My sound scape was one of hooting tawny owls and barking sheepdogs, left out in the upland fields; their calls echoing across the hills for several miles. Thirty metres away, the sound of wild boar snuffling and squealing; crashing through the understory.

We all find being under a big sky looking up at stars and constellations, the faint milky way cloud, soothing and enlightening. Lulled into a peaceful contentment by the regular clicking of my DSLR, it was the rising hairs on the back of my neck, the first warning indication. Distant dogs had stopped their canine conversation; three dogs, a mere few hundred metres away had started one - frantic barks and growls. Tawny owls had gone silent; the boars gone to ground. As the moon rose above the pine forest canopy, shafts of light illuminated the little clearings below it.

Fleeting, rapidly moving shadows; darting and pausing, sniffing the air. I thought it was a myth. It truly isnt. Wolves really do howl at a rising full moon.

This night, I won the Guiness Book of World record entries for 'fastest pack up of astrophotography equipment'. As I slid beneath the duvet at 1am, the tousle haired beauty I have been married to for nearly forty years muttered " you are in early". "Wolves" I replied. "So get back out there so I can claim the life insurance then" came the unexpected sleepy reply!

I don't get this kind of hassle up at Lowery Cross on Dartmoor! And so this is my excuse for a poor image of the Pacman Nebula - sorry folks!

Equipment and processing:

Canon 800D and Zenithstar 61ii on EQM-35-PRO mount; ISO1600, 240" x 30 with no calibration frames. Poorly processed in SIRIL, GraXpert and Affinity Photo.

Astrophotography in Croatia

 I am a lucky man. I own a motorhome and and retired. I can go on long trips. Our most recent one has been 3800 miles to Dubrovnik and back. France, Germany, Austria, Slovenia, Croatia and Italy. From alpine pastures and glacial landscapes to karst scenery and dalmation coastal geomorphology. You can tell I was a geography teacher can't you! 

Perfect nights are usually rare things on such trips.  Campsite light pollution, late arriving motorhomes,  city light pollution, cloudy nights, full moons, fog, woodland sites, roaming bears and wolves. So much to contend with. And then some of the best dark sky sites are high up, along windy narrow roads that are tricky to drive in 4T motorhome! 

Below are some images from Rovinji on the coast, a pretty peninsula town in Istria, Croatia. On this night it was a bright full moon, a starkly lit promenade, a tree covered campsite, a neon lit town on a hill.  So these are by no means good images. 

Capture details - canon 800D DSLR, samyang 14mm F/2.8 lens, intervalometer, carbon fibre tripod.  ISO 400, 11" x 30 images. everything stacked in Sequator. 

Upgrading our laptop - what does an astrophotographer need?

 My old laptop is a dell XPS 13. Portable, lightweight, compact. It has done sterling service for the last eight years. It has travelled with us extensively; been dropped and generally thrown around in a rucksack and a motorhome. Its lid is covered with stickers collected over our travels. I am very, very sentimentally attached to it. 

I love my old laptop. I was heartbroken when I discovered that windows 10 updates will stop in October. I immediately sought to upgrade my old XPS but, alas, on reading up on the dell website, I discovered that my processor was one generation too old. An interent search on various forums confirmed my worst fears; those who had tried to migrate across to Windows 11 on this laptop had had nothing but problems subsequently. 

So, the boss and I decided now was the time to upgrade - but to what? 

Well, we travel a lot so a desk top is out. As is a large heavy laptop. Maggie decided that our new one should have specs that would allow me to continue my astrophotography journey for the next few years. I am slowly progressing towards PixInSight, Star exterminator etc - so it will need some grunt! We want something which will last us another eight years, so good reliable build quality.  I was dispatched to do some research.

My old laptop had an inbuilt graphics Intel card, 256 Gb storage drive and 8Gb of RAM. It has done amazingly well, hasn't it. 

After some thinking, here is my list of 'requirements' for my new laptop

• bigger screen - 14"
• still lightweight and portable; slim build
• non touch screen but with good high resolution and colour reproduction/contrast for photo editing (1920 x 1080 minimum) 
• haptic keyboard
• 32 or 64Gb RAM so I can work more quickly with Fits files and stacking
• a good CPU quad core (minimum) processor intel i7 or i9 is my preference, for speedy stacking, rendering, etc 
• fast NVMe SSD 1 TB drive 
• a Nividia RTX 3060 GPU graphics card 6 GB minimum
• at least four USB ports - thunderbolt 4 would be preferable; built in SD cartd reader as well 
• efficient thermal cooling technology; multiple fans which are QUIET!
• long lasting battery - at least 18 hours if possible 
• good after sales back up and service

Why all the high end specs stuff? Well, I use a DSLR and shoot in RAW. RAW images can be data intensive and stacking a hundred or so and all the calibration frames as well can be really draining on computer resources. My old laptop has struggled at times, especially when using SIRIL.  The CPU does all the grunt work and so I need something more powerful. Fast storage is a must when processing and editing all these files. And of course, the more programs I download in the future, the more memory space I will need so 1 TB seems to be the thing and within my budget - just! As well as editing thye photos, I also make YouTube videos and this is where the old laptop struggled - writing voideos to storage; video editing software etc. Laggy!  This should be so much more quicker with a faster SSD drive. 

What have I ended up with?

Another Dell XPS. No seriously, I looked at hundreds of diffrent laptops of various makes on-line and in store; but at the end, I kept coming back to two brands - Dell and Lenovo. I have used them both throughouit my teaching career and they have proven to be bomb proof as far as I am concerned.  

Dell were selling off the last of their XPS ranges and offering substantial discounts as they have introduced a new 'different' laptop range this year. Consequently, I paid precisely what I paid for the old one eight years ago but this time with a £500 discount on top and the extra warranties thrown in. 

My new configuration specs are: 

• CPU - Intel Core Ultra 7 155H  12 core 3,85 Ghz processor 
• 32 Gb RAM
• fast NVMe SSD 1 TB drive 
• a dedicated Nividia RTX 3060 GPU graphics card 6 GB minimum
• 14" screen, slim, lightweight
• haptic keyboard
• non touch screen with high resolution
• battery that lasts 18 hrs
• ultra quiet two fans and four cooling vents 
• 2 year warranty extension
• 2 year battery warranty extension
• superior after sales technical support package

Basically, I got everything I wanted at a budget I could afford.  Having used the laptop for the last month, I have to say I am really impressed. It is blisteringly fast, lovely to use and rather stylish in design. The haptic keyboard is a revelation. 

Sadly the weather hasnt yet played ball and so I have yet to use SIRIL on it but I suspect it will be far faster than what I have been normally used to.  I'll let you know! 

Postscript:

I have had the laptop for just over a month now and have started some basic processing in Siril, Affinity Photo and GraXpert. The new laptop is blisteringly fast - around five times faster on just about everything I have asked it to do thus far. Take basic OSC preprocessing scripts in Siril. Old laptop, could take up to 25 minutes. Same data on new laptop - five minutes flat. Stacking data in affinity photo - old laptop - 35 minutes; same data new laptop - 6 minutes.  It really is an impressive beast. Moreover, it doesn't overheat, the fans don't get noisy. 

Basically, absolutely loving the new laptop and chose the right specs! 

A beginner's guide to post editing your first milky way photograph

 If you are interested in learning how to take a milky way photograph then just use the search box on this blog - type in 'milky way' and all the posts should materialise. 

In this blog post I am going to share how I post edit my milky way photographs after stacking them. I tend to take multiple shots and then stack them. I do foreground shots separately, process them and then blend the two together. It is a dark art and I rarely get it right but slowly I am making progress. Some days! 

This is a tracked, stacked composite photo

a separate sky blended with a separate foreground shot, both from the same location

sky details: 60" x 15 tracked at ISO 3200 F/2.8

foreground: blue hour ISO 800 15"

Sky stacked in Sequator and processed in SIRIL, GraXpert and Affinity Photo 

So, after stacking my milky way lights in either SIRIL, Affinity Photo or Sequator, what do I then do to them?  Well, this post is all about the sky/milky way bit only. I am aiming to get detail in the stars; detail in the milky way; a natural look to the sky with minimal noise and artifacting. 

Here are my steps to post editing the sky/milky way element: 

1. a 'global' edit in 'Develop' persona in Affinity photo - what other programs may call camera RAW

• White balance - cool look between 3500K and 4500K
• slight increase to exposure if the sky/milky way look underexposed - but I try to avoid blowing out the stars
• adding some contrast to separate out the milky way (MW) from the background sky
• raising the shadows slightly to reveal the MW details 
• lower the highlights slider a little to recover bright stars
• add a moderate amount of clarity and/or texture to enhance details and recover detail in the dust lanes
• some initial noise reduction - some modest luminance early on. 

Exactly same data collected but processed slightly differently 

Having made these global edits - I now duplicate the layer in the layer stack and do subsequent work on this

2.  next some curves and levels adjustments

•  firstly, pulling up the mid tones
• adding a little more contrast by adjusting dark and light ends of the histogram curve - applying a series of very small shallow S curve adjustments 
• some level adjustments to clip unwanted black levels and to brighten image overall
• playing about with midtones and shadows to darken the background sky without affecting the MW - using selections and masks

3. Enhancing the milky way detail using selections and masks 

• applying some local contrast adjustments on the duplicate layer - using high pass or unsharp filters
• applying some dehazing and clarity to selected areas to enhance detail
• some selective masking to enhance particular adjustments such as boosting contrast further
• colour balance and hue work - to make the core pop
• saturation masks to control colour boosting in selected areas of the MW

stacked in sequator - but even with ground 'frozen' mode - the foreground is still out of kilter

4. Noise reduction and star control work

• I may save the image as a Tiff at this point an put it into GraXpert for background work and denoising before bringing it back into affinity photo for further work
• I may well also put it into SIRIL and do starnet separation work to get a starless image and a starmask image. I will work on this latter image to reduce star size, intensity and frequency before doing a star recomposition. This then gives me an image where the milky way isn't overpowered by surrounding stars

5. some colour grading work

• using gradient maps or selective colour to add subtle purple, blue and magenta hues to the milky way area (this is one area I just don't understand and haven't yet got right) 

6.  some final touches 

• cropping
• removing any distractions e.g. trails
• sharpening the MW core a little more using masks

It all sounds so easy doesn't it. Well this is my workflow order. Of course where I fall down is understanding how to do masks and selections; how to use opacity and different blend modes. It's the practical tools manipulation bit in affinity photo which is proving my downfall! 

Very frustrating I must say. 

Beginner's guide to using a DSLR camera and/or GoPro for taking star trail photographs

 The Weather has been pants hasn't it. Everytime there has been a clear night recently, it has always coincided with a full moon; or I have had other pressing family commitments and so haven't been able to get out at night. 

So I am severely curtailing my ambitions for my landscape astrophotography over the next few months. What I would like to walk away with at the end of October is the following:

• a circular star trail landscape photograph of my local church
• similar photo of Windy Cross (A Granite cross and little leat waterfall) on Dartmoor 
• a star trail photo of Rame Head chapel

On the milky way landscape photo front, my ambitions are to obtain by end of October:

• Dartmouth Day mark 
• Start Point Lighthouse
• Rame Head chapel
• Wembury Church
• The Great Mewstone at Wembury Point 
• a better image of Bigbury Island under the milky way alongside one of the huge beach tractor as well

So, to the focus of this blog post. Star trails on a DSLR and/or GoPro. 

Funds are tight. I cannot afford another DSLR body at the moment. My two other cameras are a GoPro Hero 9 and a Sony HX-90 digital compact.  I think the trails will be easier to do on the GoPro, but I am open to that belief being challenged. 

Copyright: Wheal Owles by Simon Torr

So, here are my tips for using your DSLR to gain star trail images:

*source of some information: Peter Zelinka Star Trails tutorial

** I haven't yet shot any star trail images so these are my PLANNED INTENDED settings for future shoots 

Firstly equipment! You will need:

• DSLR
• dummy battery and power bank OR several spare batteries
• Stable tripod with good ball head
• Intervalometer
• wide angle lens - in my case my samyang 14mm. If you want curves - try a 24mm lens, for lines, try 50mm
• Fast SD card - you will need a class 10 UHS class 3 memory card, minimum 32gb - better 64gb

Secondly, what settings do we use? 

1. apply the 300 rule and go for 90% sky coverage in your landscape photo 
2. do one foreground shot at the start or end of your session - so that you can merge it with your stacked star trails in post editing
3. settings:  ISO 1600+ to get lots of stars and dense bright trails; ISO 100 - 800 to get fewer stars and bigger gaps between individual trails with better star colours. In an urban sky - try ISO 400 to 800 at F/4 to F/5.6
4. If light conditions are too bright - reduce ISO and open up the aperture - try F/4
5. shutter speeds - 20 to 30". However, if you use a very low ISO you can increase your shutter speed to 60", 120" or even 180", capturing more light, a cleaner image with less noise and grain. 
6. White balance 3000 - 5200K. I will be probably starting at 3600K. Don't use 'auto'
7. LNR off
8. use an intervalometer. Here it gets tricky. You will either use a 1" delay between your shots or the length of your shutter speed + 1" more. And you need to experiment first before you go out for the night. Peter Zelinka's tutorial really explains it well and you can access it here https://www.peterzelinka.com/startrails
9. I set my intervalometer to take around 3 hrs worth of shots minimum, but that's just me. 
10. set your DSLR to evaluative metering
11. Direction - face north = circles; S = downward arcs; E or W = upward arcs

So what about settings for your GoPro? Mine is a Hero 9

• Night Lapse mode
• FOV - wide
• shutter speed 30" - if in urban environments - then shorten it
• Interval - auto
• ISO 100 - 200 (or 100 min to 800 max)
• If using Protunes - Flat colour and WB of 4000 - 5500K
• shoot in RAW images
• collect 3 - 5 hrs worth of images

Equipment: 

• stable tripod
• spare batteries and/or powerbank and cable
• GoPro camera

Above is an outline of how I go about getting my star trail images. The next step is how to post edit them ad for that I use a program called Starstax.  Having not yet taken any star trails, I won't go into using StarStax until I have used it myself. 

Postscript update:

How am I progressing with star trail imagery?  

I think fair to say, not as well as I might have hoped. 

Here is my first ever star trail shot taken on a motorhome site in Dubrovnik in October 2025. 

So, what's gone wrong?

1. I was shooting on a night with a huge amount of light pollution - bright campsite lighting, rising full moon and light aura from nearby port
2. motorhomes constantly coming and going on the site caused headlight and red brake light reflections in the clouds above 
3. wrong settings in camera - ISO was too high at 800
4. poor processing in starStax - first time I have used it; ditto in Affinity Photo.

Next time: 

1. ensure there is no light pollution
2. choose better settings on camera particular ISO, shutter speed and interval between shots 

Have you got a star trails shot to share with us? Have you got any tips to help us take better star trail photos? What can we do to combat light pollution when doing star trails? 

If so drop us a comment in the box below. 

Until next time, clear skies, have fun and take care out there. 

Imaging IC1396 and the Elephant Trunk's nebula.

 This is my first attempt at IC 1396, a large emission nebula which is a region of ionized gas that glows due to the energy from nearby stars, particularly a very bright, massive star (HD 206267).

It is two nights worth of data as outlined below taken over two nights when there was a full moon, so to be honest I am pleasantly surprised that anything showed up at all!

IC 1396 has a magnitude of 3.5 and is in the constellation Cepheus, approximately 2,400 light-years away from Earth; a vast and complex area. Its most prominent feature is the Elephant's Trunk Nebula (IC1396A), a concentration of interstellar gas and dust forming a dark, finger-like structure. The entire IC1396 nebula spans over 3 degrees and has a near hollow and gas-poor interior and a complex of dark nebulae threaded throughout the perimeter. Many of the dust structures are aligned so they appear to radiate away from the stars in the nebula’s core.

Look for the reddish star which is Mu Cephei, also known as Herschel’s Garnet Star. The tenth brightest star in the constellation Cepheus, with an average apparent brightness of 4.08, it has a radius 1,260–1,650 times that of the Sun and is one of the biggest stars ever discovered; situated at a distance of about 2,840 light-years from Earth.

IC 1396A, better known as the Elephant Trunk Nebula, is a dark nebula formed by an irregular pillar of dust many light-years long. Pressure from bright stars in the core blows dust from that area leaving behind a darker region at the centre of the nebula while compressing dust around the edges, which drives new star formation. As a result, up to 250 young stars- all less than 100,000 years old, have been detected in infrared images taken of the Trunk region. The Trunk itself is about 20 light-years long. It is the first image in which I have ever captured a strong star formation area of the heavens above.

Imaging equipment used:  Canon 800D DSLR, Zenithstar 61ii refractor scope, EQM-35-Pro mount and guiding with ASIair mini, RVO 32mm guide scope and ZWO 120mm mini guide cam.

Data acquisition: two nights of same data collection – ISO1600, lights 25 x 300”, 10 darks, 10 biases and 15 flat frames. Full moon at 96%+ on each night. Location – two different sites in Cornwall.

So, what do I think about the images?

They were quite hard to process. I use SIRIL, GraXpert and Affinity Photo and somewhere along the way I tend to over saturate the colours and incorrectly process the background sky. I have overstretched the images resulting in star over-bloating as well. So, these are very much a first effort.

Am I pleased with them? Yes. Sort of. I am pleased I captured the data on very bright moonlit nights from two separate locations. The post editing? Well, as always, it is a work in progress isn’t it. 

Report card?  Considerable effort, showing some good acquisition skills but clearly more focus required in post editing! B+

These are the minimally processed first effort images 

First effort 'over-cooked' images

So a third effort will be necessary over the next few days

What do you think I could do to improve the processing further? Let me know in the comment box below. Thanks 

My most recent re-edits.....progress is slow! 😅

IC 1318 The Sadr region

 The Sadr region, known as IC 1318 or the Gamma Cygni Nebula, is a diffuse emission nebula that surrounds the star Sadr.  Around 5000 light years away from Earth, the area also includes the Crescent Nebula (NGC 6888) and The Butterfly Nebula as well - which is really IC 1318. You can see a dark thin dust alley and then two glowing cosmic wings either side of it - hence 'The butterfly'. 

The nebulas glow comes from nearby stars releasing streams of charged particles known as stellar winds; these ionise the gases causing them to emit light. 

Sadr is a yellow-white supergiant with x12 the mass of our sun and x 150 its radius. It lies at the centre of this stunning Hydrogen II emission region. 

So, acquisition details? 

This is the result of two nights worth of data, processed in SIRIL and Affinity Photo. 

Equipment used: 

• Astro-modded Canon 800D
• Samyang 135mm F/2.8 lens
• EQM-35-Pro mount
• ASIair mini with RVO 32mm guide scope and ZWO 120mm mini guide cam
• Optolong L-enHance filter clip in eos

Acquisition times:  on each night 

• 35 x 240" subs
• 10 darks
• 10 biases
• 20 flats 

I find post editing difficult. There is so much to learn and I am never sure whether I am getting the final image right in terms of tone and look at the end of it all! 

But, here are my three attempts thus far in the order I did them: 

So, this one is fairly good. I like it but I felt I could have done a slightly more aggressive black point adjustment to get the background sky darker; taking care not to blow out the stars

😧From one extreme to another. Second go and I overcooked it - too much saturation, vibrance and contrast. Back to the drawing board! 

And my third effort - a halfway house. Better sky, better colours, not oversaturated but lost the stars! 

Have I ever told you this post editing alarkey is hard work? 

Beginner's guide to taking calibration frames in Astrophotography

 When I first started out in astrophotography, there was a lot to get my head around – how to use my DSLR on manual; how to use my kit lenses, what additional gear to get; even how to focus in the dark!

My first images were stacked in Deepskystacker and when the results emerged – dust spots, red pixels, and ‘darker’ patches were scattered across the image. Very disappointing. Hardly surprising really. I hadn’t come across the term ‘calibration frames’ then. Now I have and I fully realise their importance in obtaining great astrophotography images.

So, what are these ‘calibration frames’ and what do they do that is so important? 

The frames are additional sets of images taken at the start, part way through or end of our astrophotography session. They are the quiet heroes that ensure our celestial photographs are not only bneautiful but also accurate. Simply put, when we poiuntr our cameras at the night sky, its not just starlighyt we are capturing. We also collect the imperfections of opur camera equipment - dust, noise, vignetting. Calibration frames help clean up our final images by removing or correcting these known defects or inconsistencies on our camera sensor; cleaning up our data before we start stretching and post editing it. Thinkl of them like this. Astrophotography is like painting a masterpiece but our brush is our camera sensor and it has smudges, and opur canvas, the night sky uimage, is unevenly lit. Calibration frames act like cleaning cloths and leveling tools, restoring clarity before we finish the image and start admiring it. 

I take three types of calibration frames. Each one has a specific role to play in improving the quality of my final stacked image. The types are:

Dark Frames

Biases Frames

Flat frames

But before getting into the specifics, lets remind ourselves of the other type of frames – lights!

Light frames are the main images we take of our deep sky or milky way sky objects. Rich in signal from our intended target, they will often contain amounts of the dreaded ‘noise’. Then there may be aberrations, vignetting, hot pixels, plane and satellite trails; not forgetting sensor irregularities, read noise, uneven light gradients, dust motes and more. Basically then, all the stuff that needs to be removed or corrected within them.  Our light frames are straightforward enough to capture aren’t they. We select our deep space object, align our lens towards it, set our ISO or gain and correct our focus, before taking multiple images for stacking later.

So, why is taking calibration frames as well such an important thing to do?

Dark Frames tackle thermal sensor noise. Heat produced by our camera creates thermal noise (speckles) and hot pixels. A dark frame photo is taken with the lens or telescope cap on so that no light can get into the imaging train. Same exposure time, ISO/gain and temperature as our light frames. All we capture is the noise! Having identified this noise, we can now use the frame to eliminate or ‘subtract’ this unwanted data from our stacked data. No more or severely reduced hot pixels, thermal noise patterns etc. 

A dark frame from my astro-modded Canon 800D

We can build a library of darks frames – for different exposure times – and reuse them; if you are using a dedicated cooled astro cam. However, I mainly focus on use of DSLR on this blog and here it is trickier to build such a library. This is because dark frames also depend on the ambient temperature changes encountered from one imaging session to the next. Keep our DSLR either on or off our scope when taking dark frames. I just put my lens/telescope dust cap back on and continue shooting using the same exact settings as my light frames! It takes longer in the field but I don’t mind being out under the stars! One tip for taking darks with a DSLR is to ensure that no stray light can enter the sensor area, so I block off my eyepiece viewfinder with tape. A friend puts a small, lightweight, dark coloured fleece blanket over her rig when taking them. Now that’s dedication!

So, how many dark frames should we take? How long is a piece of string? Reading around, between 10 – 20 seems the norm. I’ve seen some astronomy sites recommend between 20 – 30, arguing the more the better for obtaining a clean image. The key bit – DO NOT wait until the following night to take your darks. We take them on the night we are shooting. Remember same or as close as temperature to when we shoot our light frames.

 

A Bias frame on my astro-modded Canon 800D

Bias frames capture 'read noise'; the electronic ‘pattern’ (tiny electrical 'offset') and ‘read’ noise generated when the sensor reads the data and the camera downloads an image. Its like measuring your camera's natural hum when its sitting quietly.  We set our camera to the fastest shutter speed it can do – in my case 1/4000”, keep the cap on the lens/telescope and keep the ISO the same as our lights. The result is a map of your sensor's internal noise pattern. Take the stray light prevention measures outlined above when doing dark frames. Stacking these with our light images will help correct ‘fixed pattern’ noise and remove unwanted artifacts from dark and light frames. The image is 'subtracted' from yo9ur actual light image and so the constant buzz is removed. You are muting the background static to allow the true music of the stars to come through clearly. 

How many? 20 – 50 seem the consensus needed to ensure accurate calibration.

 

Flat frames correct uneven illumination  - vignetting, dust motes or shadows, on our sensor thus ensuring a smooth background in our final images. There are a number of different methods for taking flat frames and you can go research these to find which is best for your set up, but here is what I do:

I cut out part of a clean white T shirt and stretch it between a small embroidery hoop that is just a slightly larger diameter than my Samyang 135mm lens and Zenithstar 61 ii aperture. I then place it over the aperture of my lens/telescope and then place a small tablet over the top of this. It has an ‘evenly lit’ white screen. Keeping my camera and telescope/lens in the same set up as my light frames i.e. no changes to focus, ISO or imaging train etc, I change my DSLR to AV mode and then take short exposures, avoiding any clipping of the histogram. I am aiming to have the histogram about a third or half way across from the left-hand side. I cannot emphasis this point enough – we must NOT change our imaging train or shooting circumstances. So, no changes to camera rotation, focus, ISO etc.

Adding flat frames into the stacking of our images helps correct vignetting, dust shadows etc. They reveal how your equipment 'shades' light, allowing software to correct the image so brightness is consistent across the field. They are one of the easiest ways of boosting our final image quality and should therefore not be missed out.

A flat frame taken on my astro-modded Canon 800D. The file has been reduced in size slightly for upload to the blog. 

How many do I take? Normally around 10 – 20 flat frames. I take mine at the end of my imaging session after my darks and bias frames.

Some quick clarification by the way  – vignetting is the light fall off towards the outside of your light frame. It might resemble a dark circle.

 

I tend to use SIRIL, Affinity Photo, Deepskystacker and Sequator for post editing my astro images and each has a calibration phase when you add your calibration frames into the stack with your lights. The software then applies the various corrections before any alignment and integration. Clever software!

Essentially what seems to happen is that bias frames are combined to create a master average bias frame. This is then subtracted from the dark frames to remove bias noise. Flat frames are calibrated and then either the master bias or the master dark frame is subtracted from flat frames. Calibrated flats form a master flat frame. The master dark is subtracted from our lights.  Everything is then aligned and stacked. Probably an oversimplification of the process.

So,  should we skip doing any of them? You will hear, see, read that people do!  All I can say is I don’t. For me they are the difference between a clean astro image and one with those distracting artefacts in them.  Do I keep a library of them as a DSLR user? No! Why? I’m constantly switching lenses and telescopes. There are temperature and humidity variations from night to night. I suspect there is dust on some of my optics. Adjustments to ISO, exposure time, focus. Camera rotation to get best framing of my DSO target. The list is endless isn’t it. 

In conclusion – I hope this simple overview helps you understand calibration frames better. They are foundational to our astro imaging post processing work. Without them, our cosmic portraits are like listening to a symphony through a dirty speaker - we can hear the melody but distortion maks the finer notes. Used correctly we can remove/reduce noise, aberrations, vignetting and produce higher quality finished images. Calibration ensures the scientific and asethetic integrity of our images. We increase our chances of gaining sharp, clean vistas of nebulae and galaxies. The invisible polish that turns a night of data into a window on the universe. 

Most free programs I use do it all for me, so I just need to ensure that I have taken my time and care over capturing my calibration frames correctly.

Good luck in capturing yours.

The final image after stacking the lights and the calibration frames