How do we construct a successful deep sky astrophotography picture, you might ask? I will preface this by stating that these are some of the most difficult images to produce. From capture to processing, they can challenge you in ways you never thought imaginable.       This can lead to nights spent tearing your hair out trying to work out why something isn’t working. Ask any astrophotographer this and you will likely find the majority have wasted a night or perhaps several precious nights under the stars trouble shooting some obscure equipment issue that stopped them doing the thing they wanted to be doing - taking pictures. It is for this simple reason I keep it as simple as possible when imaging from my backyard.

The best way to learn anything in this life is to simply watch or read about the process start to finish from someone who is already doing it; then to simply try it for yourself. You will encounter problems; but I promise you, with practise you will also find solutions. Consider that no one is an expert at anything the first time they try and keep this in concious thought throughout the process - even when it isn’t perhaps going that well on the night. It may interest you to discover that this picture shown above was made, not with a telescope, but a common photography zoom lens (albeit a very high quality, fairly expensive one). Simply owning a camera and telephoto lens has the potential, with time and patience for one to be able to produce such an image. Like us all, I stand on the shoulders of giants when I learn something new. This is always the case unless you are the one blazing your own trail. I learned a huge amount from reading then attempting to put it into practise on the night.

So how do we do it? We have to counteract Earth's rotation in order to collect enough light to produce exposures which then must be stacked to reveal faint detail and slowly build up enough signal to create a picture. Astrophotography is much different to daylight photography: we have to stack and layer exposures over one another in order to display (after processing) the faint details of the night sky. In doing so, earth’s motion becomes a huge issue as the further we punch into the night sky, the quicker the stars move relative to our fixed tripod.

Enter; the equatorial mount. The equatorial mount, or star tracker, will follow the stars across the night sky. This solves our biggest issue. This one piece of equipment is a game changer not only for deep sky work, but also for astro landscape style shooting. Regarding guiding, forget about it, at least for now anyway. Guiding is the process where we have another small camera and scope matched up to a star, or pattern of stars in the night sky which plugs into the mount and provides corrections for things like periodic error in the mount. It is intended for ultra long focal length lenses and scopes to allow us to track for longer. I am here to tell you that you do not need one if you are under 200mm. I know this because I have used several star trackers, and I can track the night sky for 2 minutes at 200mm on a full frame or crop body sensor, using accurate polar alignment and balancing. This is good because, as I mentioned at the beginning of this guide - simplicity will afford the best return and enjoyment, at least for me. So now we have a mount and a tripod...I am going to lay down what matters: it isn't your camera, or lens. Any camera or lens made within the last 10 years that has live view and a manual mode can be used; whether it is full frame or a crop body it matters not. Even the lens matters little, at least initially because remember we can stop it down a little to make it sharp if it isn't great at the first few apertures (more on this later as we consider aperture’s affect on starlight).

My current kit is a Nikon Z 8 with their 70-200/2.8S zoom lens. (I decided the redcat in this picture was not for me). The latest 70-200/2.8S nikkor has fantastic aberration control at 200mm and it’s f/2.8 aperture allows other options such as shooting comets or meteors which are very aperture dependant, that slower telescopes would struggle to record. It’s stars right out to the edges remain good and have very low amounts of CA, and improve on stopping down which gives a lot of options  in how I use it. Along with this kit I use several fast primes from 14mm up to 85mm and other DSLRs to connect them into. I use these for both deep sky and astro landscape style pictures. Any camera made in the last ten years will do just fine.

So what I am saying here is, use any camera and lens that you have currently. Just make sure you use it on a star tracker, and go somewhere as dark and un-light polluted as you possibly can. Shooting from very light polluted skies is possible but much more frustrating, and harder to remove artefacts like gradients that will show up in your images later on. The best advice is, as with anything, walk before you run. Use a wider prime or zoom lens initially because the demands for strict polar alignment are much less. I recommend using a lens between around 50-200mm at this stage. Oh didn't I mention? We cannot simply plop down the star tracker, turn it on and expect it to cancel out earth's rotation; we need to align it to the North star in the northern hemisphere and a star pattern in the southern hemisphere. This isn't as difficult as it sound's and I will write more about this later on. At the moment you can refer to youtube about this until I flesh out this section of this tutorial.

So now we have our mount and tripod, along with camera and lens all ready to go. They are connected up, balanced and we are polar aligned. A couple of other important points - set your camera to RAW mode. Also set your white balance to daylight in order to stop it fluctuating between each shot throughout the night. Now we really need to get technical…

We need to think about our target. If you are a beginner, go easy on yourself and choose something large like a whole constellation. If using a full frame body a 50mm lens fits this task well, or 35mm on a crop body. I shot this target only a few years ago with a simple 50mm lens stopped down, allowing my star tracker to complete 2 minute exposures at f/4 and ISO 800. In processing I then stretched the image to reveal the faint details buried within. I use   Telescopius which is a telescope / lens simulator for astrophotography. This lets you plug in your camera, lens or telescope and frame your target. This let’s you see how your resulting shot could look. It goes further than that though, it is also very useful to physically find your target in the night sky.  The first few times, this will be the difficult part, until you find your way around the night sky. Targets which I recommend, and are very easy to find are the Orion Nebula, the Cygnus region,  the Auriga constellation,  the North America Nebula, the Taurus Constellation,  or Andromeda. This  is not an exhaustive list of course.

We have almost everything we need; except our final settings which can only be definitively set on the night. The principals that govern the correct settings are that light collection is paramount, along with balancing aberrations of your lens, ultimately achieving the best stars possible across your image. This is why astro photographers would rarely shoot wide open when using a lens. It's why the above shot was made at f/4. My final individual frames where achieved using what I stated above - ISO 800, f/4 and 2 minutes sub exposures. ISO needs to be left low to protect highlights and ideally if your camera sensor has a dual gain chip, an ISO selected considering this. Check www.photonstophotos.com for your ideal ISO for deep sky. For the Z 8, I want to be at ISO 500 for example as this is the point at which the dual gain kicks in. I then fire off a test shot and see what my histogram reveals. I’m looking for the peak of the data to sit around one third from the left. (This does not need to be exact). If it does not, I need to either increase the exposure length or change the aperture to get to approximately one third from the left histogram wall. Once I achieve this…we are ready to begin shooting. Make sure you have attached your lens heater to protect against dew, a battery pack if your camera can be run off USB (or if not be ready with batteries to switch out). Use either an interval timer or the sky watcher app connected via wifi if using a star adventurer mount. Frame up, focus manually using live view by zooming into a bright star and take a test shot. Do not rush this part; it will save the headache of a wasted time under dark skies to reveal out of focus shots headed for your recycle bin.

How much data do we need? This depends on your light pollution. Basically, the more the better the picture will be, with greater colour and less noise. It will also stand up to more pushing and pulling in processing too. In very dark sky areas, such as bortle one, two or three, even one hour can work depending on the faintness of the target. For most of us in less than perfect skies, several hours of data are required to build a picture. I try to get at least two to three hours on the average target. The Pleiades widefield shot at the beginning of this guide is over four hours of total imaging time in bortle four skies with the target at zenith (overhead in the darkest part of my sky). The first time, take as many shots as you possibly can. Evaluating the first few and then periodically during the next few hours if the stars remain sharp is important. You just completed your first multi-hour deep sky astrophotography data!  The last thing before we pack up and head to bed is to take calibration frames. I will elaborate on these soon as I build this page and the coming pages. This all said; it isn’t a picture yet. It is simply RAW data that we must stack and dig out the faint signals which lie within. Next…we stack and process it to make that beautiful end result - the picture.

This page is being continually developed and expanded. Check back soon.