Welcome to the third and final instalment of my three-part Astronomy blog series. Part 1 and Part 2 have so far given you some insight into how light travels and what you can see in the night sky with your unaided eye. This chapter will introduce you to how you can photograph the night sky to tease out even more stars, objects and details that our unaided eyes aren’t able to see.

Astrophotography is an enormously satisfying hobby and is a subject that integrates all five areas of STEAM:

• Science – using your knowledge of the night sky to understand what you are wanting to capture.
• Technology – the need to understand and use various equipment including a camera and telescope/lens. Advanced users can also teach themselves photo processing in software including Adobe Photoshop and Lightroom.
• Engineering – the ability to ‘engineer’ the best optical set up to photograph your desired target.
• Arts – astrophotography photos can create the most amazing visual art!
• Maths – using basic maths to make calculations on your camera setup and exposure settings.

Astrophotography can become a very complex and expensive hobby but it doesn’t have to be. You can still create some amazing photos with basic and inexpensive set ups – I started off with a simple DSLR camera, a cheap lens and tripod and these still serve me well today for some of my photography sessions (certainly for 1, 2 and 3 in the list further down).

Due to the depth of the subject and the various ways you can approach your technique and set up, the following will simply introduce you to some of the different types of astrophotography and then at the end I will link to a helpful YouTube video that will take you a little deeper if you wish to have a go yourself. For each type of Astrophotography, I do recommend searching further ‘how to’ videos on YouTube to broaden your understanding prior to your first session.

The Basic Principles

During the daytime, when you take a photo with your phone or camera, it will typically open and close the shutter in about 1/200^th to 1/1000^th of a second – very fast! This is so it only lets enough light through to your sensor to capture the image you need without over-exposing the image.

With astrophotography, the opposite is needed therefore your shutter needs to stay open longer to allow as much light as possible to hit your camera sensor, typically with a shutter speed of anything from 20 seconds up to around 2 minutes (and longer as you get experienced), depending on the object you’re photographing. This is called ‘exposure’ time. You’ll also need to play around with the ‘ISO’ setting of your camera too so that your sensor’s sensitivity to light is increased. The ‘Aperture’ setting of your lens also needs consideration which acts like the iris of your eye so in certain cases, the wider open it is, the better (to let in more light).

As the Earth rotates, there’s also the issue that the sky appears to move so after around 20 seconds, depending on your lens, you will get what is called ‘star trails’. Therefore, for capturing deep space objects and planets (as per 4 and 5 in the list below), you will benefit from using a star tracker mount to track the movement of the sky and always keep the object in frame of view. But all of this will come in time as you build your experience and knowledge of the subject.

So, let’s now look at the different types of astrophotography. Don’t forget - ‘how to’ videos on YouTube will be your best resource to learn more about each of these.

1. Nightscapes

The easiest way to get into astrophotography is to take simple nightscape photos. Just like you would in the daytime by pointing your camera at some scenery, the same principle applies here. Use a tripod, a wide-angle lens (15-55mm is ideal) and then use your manual camera settings to go for an exposure of around 20 seconds (to avoid star trails) to take a single photo. The best photos are those where you can have a point of interest in the foreground such as a building, monument or even just a tree (if there is no wind moving the object, otherwise it will blur in the photo). One other tip is to ‘light paint’ your foreground by shining a torch/light on the object whilst the camera lens is open (taking the long exposure photo) as I have on the tree in the photo opposite. Once you get more skilled, look in to photographing nightscapes that show the Milky Way!

2. Moon Photography

The moon is also a great beginner target as it’s easy to find and offers plenty of detail to capture with its many craters and ‘seas’. Due to the moon’s brightness, the trick here is to capture short exposures using speeds of 1/10 second or less and reducing the ISO. One photo on its own can be good enough, but to pull out even more detail, as you get more experienced, you should aim to take several photos and then stack/process them in free software packages called ‘PIPP’ and ‘AutoStakkert’. Use a zoom lens where possible of around 200-300mm but you can still capture the moon with lens shorter than this. The photo opposite is one I took using a 300mm lens and stacked in the above free software.

3. Star Trails

Star trail photos are one of my favourite types of astrophotography as they are relatively straight forward to capture and look amazing. The principles are essentially the same as (1) in the list above however by keeping your camera steady on a tripod, the idea is you use an Intervalometer (about £10-15) that plugs in to your camera and set this to automatically take c.20 second exposures continuously for around 1-2 hours (so you can step away and relax). As the stars move in the sky, each photo will take a photo of the stars in a slightly different position. Ideally you want to ensure you get the North Star (Polaris) in your frame of view as all the stars appear to revolve around this due to the Earth’s rotation. Then use a simple and free piece of software called ‘StarStax’ to stack all your photos together to create something like the photo shown opposite. Again, also find a point of interest to use in the foreground.

 

4. Deep Space

Another of my favourite types of astrophotography is taking photos of deep space objects such as gas clouds (called a ‘nebula’ – dense regions in space forming the next generation of stars) and distant galaxies including our nearest neighbour, Andromeda, around 2.5 million light years away (shown in the main header image of this blog)! This is when a star tracker or some kind of tracking mount comes in handy as you will need to take several long exposures ideally in the 1 minute (or longer) range. I generally look to take around 1-2 hours’ worth of photos, so that could be 120 x 1 minute exposures, or 60 x 2 minutes exposures. This allows each photo to collect as much light as possible. You then need to use some free software called Deep Sky Stacker (there are many others) to stack all your photos to create a single photo that is rich in data for you to then process/edit further in Adobe Photoshop or Light Room to bring the detail to life, like in the photo opposite. This photo is of the Orion Nebula (in the Orion constellation) taken from my own back garden.

5. Planets

Photographing the planets can also be a specialist area of astrophotography but does generally require a telescope with a long focal length that offers a high magnification as the planets do appear very small. It is possible to capture planetary photos with a DSLR attached to a telescope, though most of the detailed photos of planets you might see on the Internet are generally captured with a dedicated astrophotography camera (that looks more like an eye piece than a camera!). Due to a planet’s brightness, similar to moon photography, shorter exposures are often required with hundreds of frames stacked together to reduce noise and tease out the details. Sometimes these frames can be obtained by taking a video of the planet (which captures several frames per second) instead of individual photos. Or, like me, you might just be happy photographing the planet with a single image as per my photo of Jupiter here with its four ‘Galilean’ moons in companion.

Summary

Astrophotography can be very rewarding but does require patience and technique – the latter which you will undoubtedly develop and perfect with each photography session. My best advice is to take baby steps and don’t be disheartened if you don’t see the results you are expecting right away – keep at it! Take your time to understand more about each type of astrophotography by learning more on YouTube and don’t be put off by expensive equipment you might see on these videos. As mentioned, all you need to start your journey is a basic DSLR camera, a tripod and a lens (any will do to start with). And then go from there.

All the photos in this blog and the previous two blogs (except the ISS) are my own photos. These will give you a flavour of what you can achieve, but I too am still on a journey to take better photos by learning more and practising new techniques (and upgrading equipment as funds allow).

So finally, I’ll leave you with a relevant link to a good video I highly recommend from a YouTube channel that I enjoy learning from (amongst many). The subject of Astrophotography can be a little technical so there’s no harm watching videos with a bit of ‘cheese’ and humour to help understand the subject!

 

 About the Author:

Jordan Mawbey is a senior marketing professional day-to-day, but his hobby outside of work is Astronomy, Cosmology and Astrophotography. Jordan enjoys sharing his knowledge on these subjects to others to help them become more enthusiastic about looking at the night sky, understanding what is out there, and how you can photograph these objects in more detail. Follow his Instagram photography page at https://www.instagram.com/jjm_astro/