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:
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!
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?
apply the 300 rule and go for 90% sky coverage in your landscape photo
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
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
If light conditions are too bright - reduce ISO and open up the aperture - try F/4
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.
White balance 3000 - 5200K. I will be probably starting at 3600K. Don't use 'auto'
LNR off
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
I set my intervalometer to take around 3 hrs worth of shots minimum, but that's just me.
set your DSLR to evaluative metering
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.
This is my first attempt at IC 1396, a large emission
nebulawhich 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
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?
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. Simply put, they
help clean up our final images by removing or correcting imperfections for
known defects or inconsistencies on our camera sensor; they clean up our data
before we start stretching and post editing 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 work on sensor noise. Heat produced by
our camera creates thermal noise 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’
and ‘read’ noise generated when the sensor reads the data and the camera
downloads an image. 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. So, we are shooting very short exposures. 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.
How many? 20 – 50 seem the consensus needed to ensure
accurate calibration.
Flat frames correct uneven illumination and vignetting
and remove dust motes 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 and 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. Used correctly we can remove/reduce noise,
aberrations, vignetting and produce higher quality finished images. 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
Finally, I have seen my first ever noctilucent clouds, and all from the comfort of my own front step. 11.40pm looking to the north west. The light pollution from the northern part of the city dimmed their glow slightly but I am still thrilled. They are stunning to see.
Formed around 80 km above the Earth's surface in the mesosphere, tiny, minute ice crystals form around cosmic dust at temperatures around -140 C.
These photographs were taken quickly on my smartphone so they are the best but even so, I'm one happy soul!
Read for next month? Here are some things to look out for. I will update this page regularly as I find more things of interest to add.
WHAT’S IN THE NIGHT SKY FOR July 2025? (Northern
Hemisphere)
July 2nd
For next few
days look out for noctilucent clouds,
shimmering, slivery blue clouds in NW after sunset.
July 3rd
Earth reaches aphelion 2054 BST – point in
Earth’s orbit furthest from sun.
Also, Mercury at greatest eastern elongation from
the Sun (PM)
With 25
degrees separating the Sun and Mercury, this is probably best opportunity to
see the planet in the evening sky this year - should be easily seen, roughly
14 degrees over the western horizon 15 minutes after sunset.
If the planet
isn’t readily apparent, try scanning the horizon with binoculars to help you
locate it.
July 4th
Conjunction: Venus and Uranuswill be
separated by 2.4 degrees in morning. Venus easy to spot low above ENE horizon
around 0330 whilst Uranus will be tricky to pick out in dawn twilight
July 5th
Venus And The Pleiades (AM)
Venus is now
passing the M45 Pleiades in the morning sky - use lower powered binoculars if
you’d like a close view of them together - around 90 minutes before dawn - as
the sky will need to be dark enough for the cluster to be easily visible - a
good opportunity to capture an image of the two together.
July 7th
Red super
Giant Antares is 2.3 degrees NW of
this evening’s 91% lit waxing gibbous moon at 2300BST, low above Southern
horizon
July 9th
Bright globular cluster NGC 6752(mag +5.4) well placed in evening sky for next
few nights; reaching highest point around midnight local time
July 10th
Full ‘Buck’ moonlow in sky – illusion time when moon appears larger than it actually
is
July 13th
Glimpse Venus above ENE horizon around 0330 BST
July 17th
The summer triangle asterismis high up, due south around 0100 BST – look for
three bright stars – Deneb, Vega and Altair
July 19th
M45 Pleiadescluster
close to moon tonight and tomorrow night as well
July 20th
The Waning Crescent Moon passes in front of the
Pleiades star cluster in the early hours in North America.
July 23rd
Early alarm
today mag -1.8 Jupiter at 4.2
degrees south of slender 3% lit waning
crescent moon, both low above NE horizon around 0400 BST
July 24th
New Moon week
(July 24 or 25) - Try to capture the Galactic Centre of the Milky Way. It's
the last month of optimal visibility!
July 25th
Short brief
window of darkness – look for M8 bright Lagoon
nebulaand companion M20 Triffid nebulato north of teapot asterism
July 26th
Rising Venus will be 0.6 degrees SSW of Crab nebula M1–
dawn twilight and low altitude will make it tricky to catch
July 28th
Mars in evening sky joined by waxing crescent moonlow above western horizon around 2200 BST
July 30th
Southern Delta Aquariid meteor showerreaches peak activity – around 25 meteors per
hour
July 31st
Saturn rises around 2300 BST, reaching good
altitude above SSE horizon before dawn.
A few nights ago I managed to image NGC 7000 The North American Nebula and I was very pleased with the results. This post documents the night and my first image.
A day or two later and I have had another go at post editing and this is the resultant image.
And here below is the original 'first effort' post editing of the data from a few days ago.
Quite a difference isn't it. I have managed to regain some of the nebula detail particularly in the areas I'd originally blown out. I think there is better definition an structure to some of the key features as well.
On the negative side - the colour balance still isn't right is it? I think it should be a deeper red colour but maybe I'm wrong on that?
Anyway, in the spirit of being a lifelong learner, please give me some feedback. It will help me and other beginners who visit these pages. All constructive criticism is welcome in the comment box at the end of the post and thanks for taking the time to give me and others useful feedback. Appreciated.
So what were the editing programs I used second time around?
SIRIL V1.2.6
Affinity Photo
Photoscape X
I followed the following video I found on YouTube -
How did I change my normal post editing workflow this time round?
This time around there were a few changes to what I do:
I didn't use GraXpert
No deconvolution (not sure about this one - but I religiously followed the video)
Workflow was all done in SIRIL as follows:
Crop and rotation
Background extraction - and playing around with parameters more; did it twice
right hand mouse click and 'aberrations' to take a close look at the stars
Colour calibration to get background neutralisation and also accurate 'whites'
Photometric colour calibration - ensuring focal length was more accurate - reflecting that I was using 135mm lens on APS-C crop sensor DSLR
General Hyperbolic stretch - using modified arcsinh in linear mode. I had drawn a tiny square on an area of dark background sky (when zoomed into the image). Used eye dropper to set symmetry point and then moved the middle and right hand side slider triangles about; also applied some highlights protection as well. Repeated GHS x 3
Colour saturation adjustments - repeated for just cyan-blue adjustment as well
Cosmetic correction applied
Starnet applied but with 'pre-stretch' box unticked
On starless image in linear mode- Histogram transformation - just red channel - a few subtle repeat adjustments
Histogram Transformation - reducing stars by moving middle and right hand slider triangles
close starmask and re-open starless image
complete background extraction on this image - ensure no red squares are on nebulosity areas; increase samples line slider; add dither - switch between compute background image and 'original' image to see changes
Histogram transformation - adjust red and repeat - small iterations
Star recomposition - GHS - select black point in menu - make small adjustments
recrop to preference
GHS - on all colours - use symmetry point based on square in area of dark background within nebula area
colour saturation adjustments - first on global; then repeat for pink-red and then again for cyan-blue
Histogram Transformation minor adjustments
SAVE as TIFF and open Affinity Photo
In Affinity Photo:
in Camera RAW 'evelop' persona - adjustments to basic elements (exposure, white balance, saturation, vibrance, contrast, brightness etc
back to camera editor - denoising, sharpening, level adjustments
EXPORT as PNG
In Photoscape X
Film - find overlay that best adjusts final image and apply
Insert text and logos
SAVE as PNG
I learned much more about how to do GHS and use color saturation from the above video. I will try doing this again but next time including GraXpert and also Deconvolution in SIRIL
With blocked horizons to my south and west, an incoming cloud bank from the south west, a limited viewing time slot, a rare clear night for three hours and the light pollution from my neighbour's kitchen light which is left on all night, I was feeling highly pressured the other night!
I'd spent much of the day, as for most potential night observation sessions, glued to my phone - checking photopills, google maps, clear skies, sky safari plus, astrobin and the met office weather forecast. Where to go? What to see and image? What had others done on Astrobin? Plans, more plans, rewritten plans. Most times I enjoy this process but when there have been very few nights thus far this year where skies have been relatively clear, this first one for weeks - well it was causing me stress. FOMO type stress!
As it was, the forecasts began to worsen and so I gave up planning a trip somewhere. Another crushing disappointment! But, lo and behold, the skies above my house began to clear around 9pm; a direct defiance of the weather forecast apps. Would it clear? Was there a chance that I could just.........
..... set up and sneak out into the garden for a short three hour astrophotography session based on whatever I could see in the skies above my garden?Wow.....opportunistic! All that planning about to be chucked out the window! I felt quite 'devilish and rebellious' I must say! No packing the car, gathering appropriate clothing and packing flask and snacks. Just everything set up by 10pm waiting for darkness to fall. Stress free - literally moving equipment from study to garden. Simple! Wonderful!
I think I have become 'captivated by technology'. A slave to it and too geeky by far. And that's saying something as I have always been geeky! In the last year I have set up autoguiding on my basic rig, got to grips with the ASIair app and then more recently become obsessed with getting my donated EQM-35-Pro to work with all my 'gear'. And let's not get started on my obsession with mastering every post editing astrophotography programme there is!
Has this desire to get it all working and the pressure to make the best of every limited observation opportunity made me lose sight of something more important?Have I lost sight of the joy, awe and wonder at just pausing, stopping and staring at the night sky above me?For no other reason than to just appreciate its sheer beauty and immensity?
The privilege of being able to just walk out and set up in your back garden at a moments notice should not be underestimated nor under appreciated. By 11.30pm I had started my imaging session of NGC 7000 above me in the NE sky. For two and a half hours after, I just sat on my new bench below my kitchen window and stared at the sky above whilst my 'technology' went about its little workflow plan.
At first I tried to trace out the constellations above me but I soon gave up. Why? Because I had forgotten them. Now I never was good at remembering them in the first place but actually I couldn't name one. And I am sure a couple of years ago I could. So what has happened? So obsessed with getting it all working, getting it all framed correctly, getting the guiding so precise...... did I lose sight of the point of being out there in the first place?To learn new things and to appreciate the cosmos above me?
I have been privileged to have walked under the extraordinary skies of the Serengeti, the Namibian deserts, and the river estuaries of The Gambia. I've wandered the salt flats of Death Valley under the stars; clambered across the red rocks of Capitol Reef National Park and viewed the stars from the high alps and Kilimanjaro. I can remember that intense feeling of complete awe and wonder; of feeling both infinitely small and inconsequential and yet, simultaneously feeling so unique - the only one of ME - in the entire universe. (Unless of course there are actually parallel dimensions, in which case...... )
I gave up tracing constellations and focused on some star hopping instead where I made better progress. Almach to Mirach to Andromeda. Bingo. Deneb to Sadr to Crescent nebula. Result. Down to the Western Veil Nebula. Getting better! And then, I realised something immense. I was missing the point of being out there. Star hopping was utilitarian. I knew it because it was an ends to a means - finding a DSO to image.
I breathed in, slowed my breathing, kept staring up at the sky above and relaxed. A zen moment of mind clearance and slowly my mind started to wander. The bump of a snail falling off the ivy onto the decking. The scurrying of tiny feet across the top of the cushion box - Caligula, our resident rat was on nocturnal prowl. The grunting and snuffles of Hermione our hedgehog as it discovered slugs in the pea patch. The hoot of Ollie our woodland tawny owl; the rustling of ivy outside the kitchen door in the gentle warm night breeze.
Above me twinkling Vega and despite living in a bortle 5 area, the moon hadn't risen and so an hour in my eyes had become accustomed to the dark; the night sky above began to take on the appearance of a black velvet table cloth over which some uncouth diner had spilt some salt - scattered grains bright against the fabric.
Tranquility descended. No more expectations and pressure to keep checking the histogram. No jumping up to see that the cabling wasn't snagging. No trying to star hop. No feeling the need to 'absolutely learn and master' the constellation positions. Just me looking up from my comfy bench, sat on my comfy cushion, appreciating the awe and majesty of the vast cosmos above me.
And questions...... of course I had questions...... my brain can't stop asking questions.... it never rests....
...... does space actually end?
...... are there really multiple universes?
...... are we really the only ones out here?
...... is there really a theory of everything?
...... NGC 7000 existed 2500 light years ago and I'm imaging it now - but....is it still there? Has it actually dispersed?
And of course most importantly ..... is transwarp travel actually theoretically possible? And if so, when?
I really enjoyed not dashing out to the coast or up onto Dartmoor for a change! Garden astrophotography. What a revelation!
I have bitten the bullet and gone ahead with the purchase of an EOS Optolong L-enHance clip in filter for my DSLR. This was against advice from people at various astronomy retail outlets and also on various Facebook forums. Essentially, they felt I should wait until I upgraded my image train to a specific astro cam and filter wheel arrangement and then go for the Optolong L-eXtreme or some such other filter.
But, I can't afford to upgrade my image train at the moment, nor for the foreseeable future and anyway, I like imaging with my DSLR. 😕
Recently, finding a cloudless night has been about as rare as finding golden hen's teeth. But one did occur a few nights ago and so I went out into the back garden for an imaging session.
Now I was facing some constraints!
a 60% waning moon rising at 1 am
my first try at using a clip in filter with my newly astro-modded DSLR
a limited sky view - I can only image from NW to NE skies from my garden; or directly overhead towards the zenith. The steep hilly garden to the south with its tall woodland trees block southern sky views.
I decided to try for an emission nebula - NGC 7000, The North American Nebula. I've given details further down the post. A bonus would be capturing IC 5070, The Pelican Nebula.
Wanting a widefield view and after my disaster missing Rho Ophiuchi last session (because I used my Zenithstar 61ii), I opted for my samyang 135mm lens. So, equipment on the night was as follows:
Samyang 135 mm lens
Canon 800D astro-modded DSLR
Optolong L-eNhance clip in filter
Skywatcher EQM-35-Pro mount
ASIair mini
RVO 32mm F/4 guide scope with ZWO 120mm mini camera
Red dot finder scope
Celestron Lithium Pro battery pack
Two dew heater straps
Two power banks
Skywatcher right angled Polar viewer and MSM green pen laser
So here is the night's images - the same image - wide view and cropped in. Shooting details shown between the images. Remember that Blogger has a 100mb upload capacity and so I have had to reduce the quality of the images somewhat to get them to load up to this post.
Shooting details: ISO 1600, F/2.8, 300" x 25 with 10 of each calibration frame
Post editing details: Stacked in Siril; background extraction and denoise in GraXpert; colour calibration, deconvolution in Siril; finishing stretches, sharpening and colour balancing etc in Affinity Photo
So, two questions - how did the night set up go; and, how did the post editing workflow progress?
The night went smoothly. Actually one of the smoothest night set-ups I have had. From getting out the tripod to finally shooting on the target took just 40 minutes; not my normal 60 or so! Result!
I was worried that using the clip in filter would cause me some focusing issues but I whacked ISO to 12,600 and then found the brightest star I could find in the sky. Using Live View and my zoom in buttons, I was able to see the star clearly and get sharp focusing straight away. I used a strip of masking tape to then secure the focus position on the lens.
Because I couldn't see Polaris (due to scaffolding up the side of the house - recent huge flat roof leak - long story - let's not go there 😱) I had to rely on 'All sky align' mode on the ASIair mini. It worked perfectly! Five minute long exposures are the longest I have ever done and BIG result? Guiding was spot on perfect, most of the night it was below 1.0. Seriously, on a stiff to balance EQM-35-Pro - amazing!
Time spent a few weeks ago working on my imaging train also paid off. I have sorted my cabling and arranged it so that surplus cables are bundled neatly and stored on the imaging rig - reducing the cable rig weight. My son-in-law kindly 3D printed off some tripod powerbank holder clips which helped as well. I will do another post about this at a later date.
Upshot? I managed to image for around 2 and 1/4 hrs before clouds started to close in. Ideally I would like to try and get three hours worth of images. Maybe I will try and add more images on the clear night - although I am also being tugged by the desire to go off and get some milky way landscape images!
I am, in all truthfulness, always pleasantly surprised when I manage to get the ASIair working as it should. Initially, things didn't look very promising but then things settled down.
Ok, what about post editing then?
I am still using Siril version 1.2.6. I know there is a new, really whoopy new version out but I haven't bothered to download it yet because I am still trying to understand the basics on this simpler version. Small steps and learning to walk before you run and all that!
However, I am really pleased with these images. The full resolution ones show marked improvements in my post editing skills? So why the sudden leap forward? Well, I have managed to better understand GHS stretches in Siril. I have altered my workflow slightly to do more stretching in affinity photo as well. I better understand how to reduce star intensity and luminosity using JR Ritson Macros for affinity photo (thanks James). For the first time, one of my DSO photos has some 3D depth and structure to it.
At long last!
I know there are still many issues not addressed - especially colour saturation and blowing out some of the detail in core areas - but small steps as I said before. I am a 'slow' learner. Persistent, curious, determined, resilient - but 'slow'! 😁😂
So, what about the filter?
A game changer in my view. Wow. Noticeable effect immediately from my bortle 5 back garden. I won't bother doing a review of the filter as there are many already on the net - try these if you are interested:
It is easy to insert. The springy arms on the clip can be adjusted, and unlike my optolong L-pro, this filter doesn't fall out as soon as you move the camera! It seems to work well with an astro-modded DSLR. I used auto white balance for a change and got no odd colour casts. However, I need to play about with colour balance in the DSLR and see what happens on future imaging sessions. I think for the first time, I have gained some good contrast and colour saturation in one of my images. It certainly reduced the normal light pollution colour casts that I normally get. I read on many forums that if I was going to use it, longer exposures was the way to go with some people recommending between 5 - 8 minutes each. Given the longest I have ever imaged before now is three minutes - this is a game changer for me! A Bahtinov mask helps you get really sharp pinpoint stars and focus and of all the calibrations frames, the flats are the most important I suspect as they will correct any vignetting caused by the filter (although I couldn't see any on the finished Siril results image.)
And finally, what do we need to know about the two images above?
NGC 7000 The North American Nebula is magnitude +4.00, an emission nebula in the constellation Cygnus and close to the bright star Deneb. The nebula covers an area x10 the size of the full moon and was first discovered by William Herschel in October 1786, from Slough! When light pollution was obviously not an issue!
It is a huge interstellar cloud of ionised hydrogen and the shape we see from earth is caused by a band of interstellar dust that lies between it and our planet - this dust absorbs the light of stars and the nebula itself and somehow causes this shape to materialise to our vision. Can tell I'm no astrophysicist can't you! 😁
The portion of the nebula that represents Mexico and central America is known as the Cygnus Wall and is an area of concentrated star formation.
From us to the nebula is around 2,500 light years.
So why do we see red? The hydrogen alpha area shine because their hydrogen gas has been ionised by UV radiation from a nearby hot star. For a long time it was thought that this was due to the proximity of Deneb, but not so! Its surface temperature is only 8500K. A star with at least a surface temperature of 35,000K is required. Deneb is not hot enough and too far away from the middle of the nebula complex.
So, where is the UV coming from? There is a star off the 'Florida' coast area of the nebula which may be a contender. It appears small and dim from Earth because it is behind the nebula but it is closer than Deneb and its surface temperature is 40,000K. Ideal!
And IC 5070 The Pelican Nebula?
Tricky to discern but I have circled it above. You will need a little imagination here! Early astronomers thought the nebulous gas emissions resembled a pelican! Nope! Me neither but hey there we go!
Anyway, it is an area of very intense mixed star formation and gas cloud formation and is highly studied by modern astronomers today. Light from energetic young stars are slowly transforming cold gases to hot ones, so causing an ionised front to slowly advance outwards.
IC 5070 is divided from NGC 7000 by a dark dust molecular cloud area.
Still can't see the Pelican? Look for a dark dust cloud eye and then a long bill. The bright front of ionised gas curves away forming the head and the neck.
Nope, me neither! And normally, as a geographer, I am really good at this 'spatial awareness' malarkey!
