Equipment - Making a DIY right angled viewfinder for a star tracker polar scope

Newly arrived to my blog? Want to know more about me before you dive into my posts? Why not visit the home page first and start your exploration from there: 

https://undersouthwestskies.blogspot.com/2025/01/welcome-to-my-new-astronomyastrophotogr.html

And welcome. Welcome to 'UnderSouthWest Skies'. Thanks for stopping by. I hope you find the experience worthwhile. This blog post has been written from my own 'beginner perspective' after doing lots of reading on the topic below.  In getting my head around it all, I may have got odd bits slightly wrong; but, like you, I am on a leaning journey, so please forgive any unintentional errors.  Meanwhile, clear skies to you. Take care and thanks for visiting   Steve aka PlymouthAstroBoy 

Finally, I have got around to making a right angled polar scope viewfinder. The cost of them is around £80 mark with postage, here in the UK. I had an old pentax DSLR right angled view finder and I was sure I could 'adapt' it. Now there is an issue in that this old one mirror flips everything horizontally....but more of that little quirk later in the post. 

I've wanted one of these right angled viewers for quite some time. I find it increasingly difficult to bend down and look up through the central polar scope of my skywatcher star adventurer tracker (same for my Ioptron sky tracker as well).  There isn't an astrophotographer alive who uses a star tracker who doesn't understand this issue. Here at a latitude of 50N - the tilt of the tracker is such that when the polar scope is inserted, you are on your knees with your back arched to look up through it. If you can do that! When I'm on my knees below it, my eye is around 14" away from the viewfinder - rendering it useless! If I try to get underneath it and closer, I invariably end up knocking the tripod and then struggling to get back off my knees - very frustrating! 

When doing DSO astrophotography and using my ASIair mini - then there is no problem if I am slightly out in the initial polar alignment as the ASIair helps me correct it quickly. But when doing milky way astrophotography - then a right angled viewing gizmo is going to be very helpful indeed. 

So what stuff did I use?

• an old pentax right angled DSLR viewer
• electrical tape
• an old polar scope cover piece I had knocking about
• some very tiny phillips screws 

(I should at this point just explain for those not in the know, that a polar scope is essential to getting good alignment with the stars so that the camera tracks their movement above and trailing stars is avoided. This involves aligning the tracker with the north star Polaris. The bigger the lens you use, the more accurate you have to be in your alignment processes - otherwise you will have horrible trailing and photos that cannot be stacked together in any available software.)

I removed the metal silver viewfinder frame off my ebay purchase by undoing the four tiny screws and then took the protective cover lid off the polar scope. Using the silver viewfinder slot as a template I then marked out drill holes and also a central large hole to be cut out.

Ten minutes judicious use of my multi-tool with drill and then sander bits and hey presto - the protective lid had been cut out. It was then just a matter of screwing the lid back onto the DSLR viewfinder and then doing a few trial fits. 

It proved to be a little loose but a thin strip of duct tape on half of the lid lip - turned it to a fairly snug push-on fit. 

Does it work?  OF COURSE IT DOES! 😁

I have genuinely surprised myself - no more wet knees, cricked neck or wrecked back muscles. 

And it works on the star adventurer too.

So what about the flipping issue? 

Ok, how best to describe this? For some reason, the right angled viewer mirror flips the view of the polar scope reticules. So, 3 o'clock is at the 9 o'clock position and obviously, 9 o'clock switches over to the 3 o'clock position.

What does this mean in reality? Well when positioning Polaris on the correct place in the inner circle of the reticule using a polar alignment app to help determine its position - if Polaris is shown at the 5 o'clock position on the app, on my reticule, when using the polar scope, it will have to be placed at the 7 o'clock position instead.  It takes a minute or two to get your head around it - think mirror flip of the reticule along the vertical axis. 

It may sound confusing but in reality is quick and simple to work out; as long as I remember!! 

I spent around £2 in all instead of £80 so I am happy and I have reused/recycled something to boot. 

With plastic 3D printers etc - I am sure there is a free template for making the bit which fixes a viewfinder to the polar scope on the tracker. 

I found this Sky at night article which gives a better overview on how to do it than I have above 

https://www.skyatnightmagazine.com/advice/build-a-right-angled-polarscope-adaptor

Tutorial - using Sequator

 How I have been using Sequator thus far in my astrophotography learning journey

Around two years in now to learning, from scratch, i.e. no knowledge base whatsoever, how to

·        Use my DSLR in manual mode

·        Do some basic astronomy using a beginner’s telescope

·        Complete some basic astrophotography – both deep space targets and milky way landscapes

One of the free software programs I got to grips with early on was Sequator – mainly for stacking my very limited milky way landscape images. Below I outline my Sequator work flow.

Remember, this blog is written by a complete beginner to astronomy and astrophotography – for other complete beginners! Essentially it is a record of my learning journey in these fields. Mistakes, warts and all!

I am doing this post on Sequator today because some one emailed me and asked if I had any basic workflow notes for a complete beginner. They had been looking at my ‘Beginner’s guide to taking your first milky way photograph’ series; in one blog post I mentioned my using Sequator but didn’t expand on it. Luke, this post is for you buddy.

 

Firstly, lets start with – What is Sequator?

It is a free, at the moment, software for windows platforms. It stacks and aligns RAW or TIFF file night sky images, and in doing so removes random noise. An added advantage? It handles images with a little bit of foreground in them. All the better then! And, bonus, it will help with other challenges such as light pollution, distortion, hot pixels, etc. I found the basic functions quick and easy to learn, understand and set up ad I have put my workflow notes on sequator further down this post. Remember, I am a very new beginner astrophotographer. So, I am sure I have missed things out, for which I apologise. But the aim of this post is to give you something to work with initially if it is the first time you have come across Sequator.

As well as light images, you can add darks and flats as well. The basic settings for processing the images are straight forward. There are other options that can be selected depending on the images being stacked and these are explained in the manual which can be viewed here: https://sites.google.com/view/sequator/manual

 

 

Here then is my beginner’s workflow using sequator:

1.       Sometimes, not always, I may batch edit my lights before placing into sequator – using affinity photo – NOTE: only edit exposure, contrast, highlights, shadows, and WB – I am aiming to try and reveal further detail from shadow areas and prevent blowing out of brighter stars -  if you do this, save them as TIFF files at end

2.       Open ‘Star Images’ – drag and drop light images into sequator (SQ) NOTE: star frames = lights; noise images = darks – use same number of these as lights added – at least 5 - 8; vignetting images = flats

This is one of around 15 images I collected on the night

ISO 3200 f/2.8  11"

I have blocked out the number plate for obvious reasons

3.       Check ‘output’ box and name file – save as Tiff 16 bit file

4.       SQ automatically selects image as base image – double click base image to choose image I want.

5.       Composition – ‘align stars’ for all images with foreground or just milky way and/or stars. (If doing star trails – select ‘trails’ instead). On ‘Accumulation’ – select ‘best pixels’ – slider across to HIGH – this will remove satellite and plane trails from final image

6.       Click ‘freeze foreground’ (bottom LHS) if images contain foreground elements. Check box ‘selective’ alongside. Slider across to ‘strict’. Select ‘best pixels’

7.       Sky region – allows you to help Sequator decide which part of the image is sky and which part is foreground.  Use ‘boundary line’ if you have a flat non punctuated horizon line between sky and foreground. Use ‘irregular mask’ for complicated horizon or foreground objects punctuating it. Mouse scroll wheel will green paint in sky area. Leave little gap between foreground and sky that has been blanked out. (Right mouse click = eraser for mistakes). Click ‘auxiliary highlight’.

8.       Auto brightness – off. HDR – off (although try as on if different exposure levels between images – if final image is over exposed – redo and check both these to on) ‘Remove dynamic noise’ – on. It removes hot pixels – especially useful if images are long exposure ones. If not using dark images – reduce distortion effects – I keep on ‘auto’ as it seems to remove any star streaking in the outer edges and corners of my final stacked image.

9.       Check ‘light pollution’ – only if present in images. Check ‘uneven’ or ‘deep sky’ – depending on conditions. Don’t apply light pollution too aggressively. I find it gives horrible results and so unless there is major light pollution – I don’t use it.

10.   Can check ‘intelligently aggressive’ box or leave unchecked an use slider to determine how much light pollution compensation to apply. Default – check the box.

11.   Check ‘reduce distortion effects’ box to auto. Check ‘complex’ box at bottom

12.   Ignore rest of boxes on menu

13.   Click ‘start’

14.   On final image – zoom in and check any areas with trees etc for stacking artefacts etc.

 

Around seven minutes processing to this, the final stacked image, saved as a TIFF file and ready to import into Affinity Photo for further processing work 

In Affinity Photo, I do some post editing work on the final TIFF image from Sequator. Post editing skills development is a focus on mine for 2025. Why? Because I really suck at it! 😭

Anyway, from the image above via the images below: 

and finally ending up with this: 

Best I can do with my current limited post editing skills and knowledge of Affinity Photo tools and workflow practices. Ho Hum! Not Bad for a first effort I guess. 

Sequator can be used for star trails as well. I haven’t done any star trail work yet but if you are interested here are two websites that give tips:

Star trails in sequator

https://www.skyatnightmagazine.com/astrophotography/star-trails-software-sequator

stacking milky way images in sequator

https://www.ntounas.gr/how-to-stack-milky-way-photos-using-sequator/

 

Two videos about Sequator that I found useful were:

As always, I hope this has been helpful if you are a beginner. If I have anything wrong or if you can offer some better tips, then please drop me a comment below so that I can update the post.

As always, dark skies to you all, stay safe and take care out there. Have fun

Steve 

Beginners guide to taking your first milky way image - 6 getting a milky way 'selfie'

 How to take your first milky way ‘selfie’

An aim for this year; to get a decent milky way selfie!  

Below are the selfies I took last year. All of them can be significantly improved upon.

So, what have I been doing? What do I need to do to raise my game further this year?

This is post 6 in my blog series ‘Beginner’s guide to taking your first milky way photograph’ – a series in which I share my learning journey thus far towards this aim. As always, please remember I am writing as a complete beginner to astrophotography and the sole rationale for my entire blog is one of helping beginners (like me) make some rapid ‘basic skills’ progress in their astronomy and astrophotography knowledge.

My first effort at a milky way selfie taken at Mesa Verde Lodge in USA

In the car park  battling with stray car headlights and random security lighting coming on and off 

This was a single exposure 

What equipment do I use to obtain a milky way selfie?

·        Canon 800D DSLR

·        Samyang 14mm f/2.8 or Canon 22mm f/2.8 lenses – affordable, sharpish, wide angle lenses basically

·        Tripod

·        Intervalometer (although I am thinking of getting a remote shutter release at some stage this year)

Previous posts will give you tips about planning for milky way photography, additional equipment needs and basic camera and base astro settings. But, here I will stress a couple of things I discovered last year.

For a good selfie, you need a dark sky location.

Secondly, if you are doing a silhouette composition, you will need to find a location where you are higher than your camera i.e. you are shooting upwards slightly so you are silhouetted against the milky way. You can also use a light source such as a light orb, headtorch or adjustable LED panel as well.

Your image composition should tell a story - see my previous post on composition tips. If I am doing a ‘headtorch looking up to milky way shot’ I shoot in portrait. If I am using an orb to light some of the landscape around me – I shoot in horizontal.  

To get a sharp silhouette or image of myself, I am to make my self smaller in the frame by either going away some distance from my lens or by using a very wide-angle lens which will make me look smaller in the frame. In either case I am trying to be not further than 8 – 12m maximum from my camera.

I found focusing your camera for a selfie shot to be tricky. I have given tips on focusing at night in a previous post on camera settings. For now, I’d suggest you either focus on the sky itself (infinity) and you stand somewhere as close to the hyperfocal distance as you can. Alternatively, I an focus on myself – I mark where I am going to stand, return to my camera and then focus on that marker.

Of course, the issue about a selfie is simply this – how long can you stand still for? How hard is it to stand still during the exposure? If you are holding a lighting orb? Or when there is a slight chilly wind blowing? Practice getting a comfortable pose. I found that breathing out very slowly when taking the exposure helped enormously. Alyn Wallace in one of his videos I have embedded below recommends a sitting pose if you find standing for any length of time difficult.

 

Taken down the Roseland peninsula in Cornwall at Treveague Farm

Another single exposure but one where I held the light orb for too long so that it completely washed out the motorhome 

What camera settings do I use?

·        Manual mode

·        RAW

·        Lens focusing – manual

·        No light pollution 1600/3200 ISO; light pollution then 800/1600

·        Not using star tracker – then shutter speed 10 – 20” depending on 300 rule and lens focal length with aperture f/2.8;

·        Doing two images – tracking and stacking sky – f/4.0, ISO 800, 30” shutter speed; combined with a blue hour foreground exposure with me in it, experimenting with shutter speed, aperture and ISO settings  

·        I tend to do test shots irrespective of whether single or tracked or stacked exposures – checking against histogram

How do I take the photo if I am standing in the scene?

You will need a remote shutter release, or an intervalometer, or use your camera’s internal shutter release timer.

Again, the videos below give plenty of tips but this is how I do it. I use an intervalometer on which I set a delay – that’s the time period I have to get into my location and pose. I also have my camera’s 10” delay setting switched on. This means once I am in position, the 10” delay on the camera will then kick in – I can see a red flashing light or hear a bleep when that happens – this is when I firm up my pose!  I then mentally count down my exposure time in my head and then add another 10” on top of that before I finally move out of pose.

Single exposure with illumination from my smartphone

Milky Way at Wembury Beach

Did this work last year?

Yes…..and no……!  So what am I going to do differently this year? Not sure yet is my answer. I will start with what I did last year and then try something different. Rome wasn’t built in a day. I am expecting lots of duff shots but that is part of the fun. I tried single exposures, so maybe try and perfect this a little more and do some stacked/tracked/blended shots this year as well. 

If I make any changes to the above approach, I will add a postscript update below.

How much didn't go well in this effort? Where do we start? 😭

Well, I tried although Lord knows why! 😆

In the meantime, if you have any better tips and approaches, then why not share them in a comment below so that future post readers can learn from your experiences too

Dark, clear skies, stay safe, enjoy the forthcoming return of the milky way to our northern skies

Steve

 The videos below helped me on my first steps to taking a milky way selfie 

 

Beginner's guide to taking your first milky way photograph - 5 stacking and tracking

 This is the fifth blog in a series of posts in which I share what I am learning on my ‘journey’ towards obtaining a good milky way night time image. In my second year chasing down this aspiration, last year was dabbling and learning lots. This year, I want to ‘nail’ one or two good milky way landscape images. It’s a mission! Whether I can deliver on it or not is a moot point though!

If you have just arrived at this page, you may want to go back and read the first four posts in this series before reading this one. They sort of follow a logical order.

This blog post series shares what I have learned thus far to help encourage those of you seeking your first milky way image. Remember I am still at the very beginning of my learning journey. I am no expert. I claim no expertise in any way at all. A complete novice in photography and astrophotography. This entire blog is written from that perspective – a chronicle of my learning journey written by a beginner for other beginners. I know very little about anything frankly but therein lies the attraction. If I can do it with my very limited knowledge – then so can you; and probably better, as I am a rather slow learner at the best of times.

As always, if I have made any mistakes in my posts, I apologise. Please drop me a comment highlighting the issue and I will correct it immediately.

Please note: I will not be going into huge depth about how things work and why we do things the way we do. I’m not dismissing the importance of having a theoretical understanding – its critical – I’m just saying it’s not the focus of these blog posts. My aim, is to just get you out there, obtaining a first milky way image.

 

To help you achieve this, I will outline some simple answers to these questions:

1.            What equipment do we need?

2.            What advanced planning is needed to ensure success on the night?

3.            What base settings can we use to help us get success?

4.            What foreground composition considerations do we need to make?

5.            What are the different techniques for getting a milky way photograph?

6.            What do we need to consider if we want to do a milky way selfie shot?

7.            How can we improve our milky way photography skills?

8.            What is a ‘beginner’ workflow for post editing our milky way photographs? 

 

Our fifth question then - What are the different techniques for getting a milky way photograph?

Up to now in this series of blog posts, I have been looking at doing single exposure images of the milky way in a landscape setting. I touched on occasionally, an alternative method, doing two separate images – one exposed for the sky; the other for the foreground. We then blend these in post editing to create one single image.  At its simplest, I call this technique ‘exposure blending’. We might return to this technique later in the post.

However, there are a series of other techniques that we could use to get our first milky way image. The key concept, isn’t it, is about getting as much light as we can to our sensor through longer shutter speeds or wider apertures – but this can bring the problems. Longer shutter speeds introduce movement errors; wider apertures mean more of our scene will be out of focus.

However, there are other approaches we can adopt which can mitigate some of these impacts:

·        Star stacking

·        Using a star tracker

·        (Long exposure foregrounds)

·        (Focus stacking)

This is a post series by a beginner for beginners with the aim of helping you obtain your first milky way landscape image. Once over that first hurdle, you will be so keen to get other better images that you will advance your own learning rapidly through YouTube tutorials, on-line reading and plenty of practice. I am a very slow learner as you will have already deduced from previous posts – so it takes me time to assimilate and understand the basics!

 

This is one of the very first tracked/stacked/blended exposures I took

6 tracked images of 120" each, and stacked in deepskystacker. 

I then did a separate foreground exposure and blended them very badly together post editing.

The sky shots were done 100m away out in a desert section. I had been warned about mountain lions roaming the area so I remained close to the motel ranch entrance. It was a very dark sky location and when a ranch domestic moggy suddenly appeared between my legs meowing loudly, it is the closest I have come to a major instantaneous heart attack! 

So, lets investigate the technique of star stacking.

In star stacking – you take multiple photographs of the sky and stars using short shutter speeds. These are then aligned in software which creates a single final image – like an average of them all. This approach reduces the amount of ‘noise’ in the image.

If you do deep sky astrophotography (my other passion) then you will be familiar with ‘stacking’ multiple images.  Stacking allows you to use faster shutter speeds for pin point stars, and smaller apertures/higher F-stop numbers to improve the depth of field in your image, the focus of the stars and reduction of aberrations.  It sounds counter intuitive doesn’t it – faster shutter speed and narrower aperture – but because you have taken lots of images and stacked them together – you are getting, effectively more light into the final image.

What equipment will I need for star stacking?

·        Tripod and ball head

·        Intervalometer

·        (Lens warmer)

·        (Star Tracker)

 

What would be good starting settings for star stacking?

Firstly, you compose your scene. See my previous post about compositional tips.

Then we set our base astro settings. I start with ISO 800 or 1600; F/2.8 and then a shutter speed that is matched to my lens focal length (see my post on settings). I’ll go for a shorter shutter speed than the 300 rule suggests for my crop sensor camera so that I can ensure pinpoint stars.  It is however a balancing point as a shorter shutter speed means I will not get as much detail out of the fainter areas of the milky way. ISO wise? You can correct exposure during post editing. I find that on my camera if I use too high an ISO it produces images with lots of noise – which is what I want to avoid.

How many photos to take? I take many in quick succession. Nothing about camera position or composition gets changed between exposures. I tend to take between 10 and 15, depending on my base astro settings. 15 photos at 10” = 150” of integration time (the combined exposure time total). 150” is approximately 2 and a half minutes – that is a lot of light gathering! But there is another reason why between 10 – 15 is ideal – during that shooting time – the stars above are moving – well changing position as it is us on Earth who are moving beneath them. Anyway, the stars positions will change significantly, the more exposures you take. Keep it simple!

It is the opposite when doing deep sky astrophotography – the more images you stack, the better the final image is likely to be. With no foreground to consider, you just must periodically reframe your target back into the middle of your frame.

 

This was a single exposure shot 

What about the foreground element in these milky way shots?

If I am star stacking, I make it a personal rule that I am doing a separate foreground image, from, as far as possible, the same tripod position and ball head angle. I am exposing for the foreground specifically, not worried about star trailing and will probably be thinking about hyperfocal distance or focus stacking. I will be using a lower ISO. I may well try and take each exposure at a shutter speed of 1 – 4 minutes. I’ll be watching the histogram with an eagle eye. In saying all this, a friend, also a beginner, prefers to go for one long shot using the hyperfocal distance method – so a shot somewhere around 4 – 10 minutes. I’ve not tried this approach – I would worry about something moving within the shot during that time. For example, on my south coast, there are plenty of fishing boats out at night – a moving fishing boat will leave a significant trail across a 5-minute image!

I have explained these techniques regarding foreground images in a little more detail in my previous post on camera settings for milky way photography, which you can access here: https://undersouthwestskies.blogspot.com/2025/02/beginners-guide-to-taking-your-first_20.html

 

What are the advantages and disadvantages of the star stacking approach?

Advantages:

·        more integration time but with benefit of narrower apertures and shorter shutter speeds

·        reduced noise visible in final image which means more detail is revealed and a better noise to signal ratio – this is because multiple photos average out the noise resulting in clearer images

·        stacking software tends to remove satellite and airplane trails (not always, but most of the time)

·        pin point sharp stars

·        increased detail for post editing work especially with regard to colour accuracy

Disadvantages:

·        the time it takes to do multiple exposures

·        potential alignment issues if there has been wind movement during the taking of the images; some star trailing if you left too longer gap between the multiple exposures

·        increased post editing time – extra steps and complexity using some of the software; and you must raise your game in terms of understanding some more complex editing techniques (which is my current BIG problem!)

·        potential loss of detail in the foreground – my sequator images always appear with blurry foregrounds which are dark and lacking in detail – hence my shifting to taking a stacked star sky image and a separate stacked or single long exposure foreground image and blending them post editing to one image

·        over aggressive smoothing and averaging during stacking software processing – leading to an over smooth image which lacks milky way/star detail

What software will you need to stack the images you collect?

There are three pieces of software that can stack your collected images

·        DeepSkyStacker – free and great for sky shots with no foreground

·        Sequator – for images which are predominately sky and a small amount of foreground (around 10% or so)  Windows platform

·        Starry Landscape Stacker for Mac users

I will do future posts soon about using Sequator (for beginners) and a similar post for DeepSkyStacker – as I use windows platforms. It will be part of my post about post editing work flow for a milky way image. Although I won’t do anything on using Starry Landscape Stacker – I will post some useful blogs and YouTube tutorials which give details for Mac users to follow.

 

A stacked shot using sequator for the first time

I clearly got my base astro settings wrong in this image sequence

How can we use a star tracker to gain our milky way image?

I love my star trackers. I have two – an Ioptron Skytracker Pro and a Skywatcher Star Adventurer 2i Pro. The former I use for milky way imaging; the latter for that and for deep sky astrophotography as well. I am considering an upgrade of the SWSA2i to a SWSA gti GOTO model but that is all the subject of a future post!

So, if you are new to the concept of star trackers – what are they?

Trackers go between your camera and your tripod and they move your camera in rotation with the Earth so that your stars are followed precisely with your camera and there is no star trailing. Basically, a tracker is motorised and allows you to compensate for the rotation of the Earth.

It brings huge benefits:

·        You gain far longer exposures – I can easily get up to 3 – 4 minutes on the SWSA2i with no problem. Using my milky way lens – I can get 5 minutes+ easily if I wished.

·        That is a huge amount of light capture and a higher signal to noise ratio for a single exposure.

·        It results in images with less visible noise ad better colour accuracy

·        Images have more detail within the sky and are sharper throughout. Perfect!

·        Moreover, I can use narrower apertures and lower ISO’s – so I can go to ISO 800/1600 maximum consistently. Narrower apertures also lead to less aberrations and vignetting

I wrote a previous post on how I set up my SWSA2i with step-by-step guidance:

https://undersouthwestskies.blogspot.com/2025/02/beginners-guide-on-how-to-set-up-and.html

Here are my steps:

1.       Level my tripod – I have a bubble level on my tripod but I also use a small spirit level as well.

2.       Attach my equatorial wedge mount to the tripod – I don’t use the wedge that came with the SWSA – it was the first thing I replaced as I found the original insufficiently precise for my deep sky astrophotography – instead I use a William Optics wedge. Far superior – well engineered. However, I want to stress that for milky way photography with smaller lenses and camera weights – I found the original wedge was more than satisfactory.  The wedge by the way is also known as an altitude-azimuth mount! One of the things you must ensure on such a wedge is that you have set your latitude – your angular elevation. Don’t forget to do this.

3.       The tracker mount now goes on top of the wedge and I make sure it is securely mounted and that the level of the tripod hasn’t changed.

4.       At this point I might add in my optional counterweight kit – to balance my lens/camera rig and reduce wear and tear on the motor itself.

5.       Before going any further, I will now carry out the Polar Alignment procedure using the little polar illuminator which comes with the SWSA – I will outline this process in more detail later in this post. I also use a green laser pen to line up with Polaris – mine attaches to the viewfinder on the tracker – making it so easy.

6.       Having ensured an accurate polar alignment, I now attach the base plate and ball head to the tracker mount. I prefer a ball head but you might use some other accessory to attach your camera – a two-way head; a MSM Z plate etc. Be very, very gentle – try not to move the tripod or mount even a fraction – otherwise your polar alignment will be out and you will have to start the set up again.

7.       On goes my camera/lens combo. I use a L bracket on my DSLR (see previous post on camera settings). I add on any accessories – so dummy battery pack, intervalometer etc. However, this is where you can throw out your polar alignment so,

8.       Redo your polar alignment or at the very least re-check it again. Fine tuning may be required.

9.       Now do some test shots – I turn the tracker on and do a 30” and 60” test shot to see that the tracker is working properly and that there is no star trailing. Zoom in to the review image – check the corners, the centre – are stars pin point sharp dots? All being well – I now do test shots at 120” and 180” as well. Pinpoint dot stars – then I am ready to go.

 

My Polar Scope app to help locate Polaris correctly 

What is polar aligning?

A tracker has to have its rotational axis aligned with the north celestial pole (NCP) or the south celestial pole (SCP). In the northern hemisphere – we can use Polaris which sits close to the NCP and this is what I am focusing on now in this blog post. Getting sharp pin point stars really does rely on getting polar alignment correct.

How to locate the NCP and the SCP

If I use my 14mm Samyang lens, then I can get away with just a rough alignment to Polaris. I use my green laser pen which attaches to my tracker polar scope. Quick and easy.

 For a precise polar alignment, I will use the polar illuminator, the green laser pen and an app that comes with the SWSA tracker. It shows precisely where to place Polaris in my polar scope reticule for any given time in a particular day.  I will adjust both altitude and azimuth knobs until I get this precise locating of Polaris.  When this adjustment has been made and my various knobs have been tightened, I check that my hemisphere switch is set to north.

 

The polar clock inside my SWSA app 

What are my base astro settings and additional equipment for tracked images of the milky way?

·        Aperture F/2.8 although do some test shots to see which aperture gives you best result. There is a case to be made for stopping down to something like F/4.0 - you can do longer shutter speeds to make up for this - the narrower aperture will bring better focused, sharper sky and greater depth of field within a scene

·        Focal length 14 – 35mm max

·        Shutter speed 120 – 180” normally. Sometimes I will go up to 240 or 300”.

·        ISO 800 (although I often find my Canon 800D performs better at ISO 1600 for some strange reason) If it is windy – reduce your shutter speed length and increase your ISO a little.

·        Check your histogram – most of the information should be in the midtones zone. Zoom into one of the nebula that will appear in your milky way core image an see if that is correctly exposed and detailed – if so – all is good

·        Remember a tracker will blur a landscape element – so if you use a tracker – separate sky and switch off tracker for separate foreground images to later blend post editing.

·        I use an app with my tracker that also controls my camera settings – you made need an intervalometer. Have a lens warmer on standby as well just in case of high humidity/fog. You camera will get warm taking longer and more numerous exposures.

I hope this blog post has given you an overview of stacking and tracking techniques. I found the videos below particularly helpful. 

 

As always, any mistakes, please forgive me - post a correction in the comment box below and I will get it sorted in the main post text above. Similarly, any further tips, thoughts or observations on tracking and stacking for milky way images, let me know below. 

It just remains for me to wish you clear skies - stay safe, have fun

Steve