Astrophotography - Getting Started

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There are some truly stunning photographs of the night sky out there. I recently posted my photograph of the Milky Way on social media and was asked if I would do a blog post on how to get started with astrophotography. It is quite a long post, but wanted it to be a step by step guide. You might want to get yourself a cuppa...

First things first. You need to be aware of the limitations of the kit you have. If you have any sort of camera from a camera phone upwards you will be able to take some sort of photograph of the night sky, but if you are after NASA style photographs of galaxies and planets you are likely to be disappointed as you need some serious kit, including a telescope with a tracking mount and a specialist CCD camera. This post is intended to get you started with minimal kit as there are  still very many great shots you can get. All the astro photos you see on this blog are taken with a non-tracking tripod and my Fuji XT-1.

Astrophotography is a great hobby, it is really rewarding, as it can take some time to get the shot you want, but it is such a rush when you get a good photograph! By the way, if you are afraid of the dark, or don't like standing in ditches in the middle of the winter, in the dead of night  astrophotography probably isn't for you. 

By the way, if you are afraid of the dark, or don’t like standing in ditches in the middle of winter in the dead of night, astrophotography probably isn’t for you. 

So here is the minimum amount of kit you will need:

  • A camera which you can trigger remotely, either from an app or from a cable release (you can also use the self-timer). You need to do this to avoid the camera vibrating when you press the shutter as this will ruin your shot.
  • A sturdy tripod
  • A wide angle lens, preferably prime if you have it. Anything wider than 50mm full frame will do nicely. The faster the better. f2 or faster is ideal, but if you don't have that, use what you have.
  • A star guide or app. I like Sky Guide, but any will do. 
  • Warm clothes and a flask of a nice hot drink. Don't underestimate how darn cold you will get.

Learning the Night Sky

In the Northern Hemisphere at least, we are heading towards autumn and the nights are drawing in. If you are not familiar with the night sky, this is a great time to go outside on a clear night and start to learn to navigate around the heavens. Use your app to be able to locate various constellations. The winter sky is great for this as you will see Orion, The Plough, Cassiopeia and other well know constellations.

I can’t emphasise how important it is to understand the constellations and what you are photographing, I have seen so many beginners take a badly composed shot where they have cut the top off a constellation. Consider it similar to cutting off Great Aunt Maud’s head in a family photo.

It is really worth doing this as it will help when you are trying to compose your shots. I can't emphasise how important it is to understand the constellations and what you are photographing, I have seen so many beginners take a badly composed shot where they have cut the top off a constellation. Consider it similar to cutting off Great Aunt Maud's head in a family photo.

Light Pollution

Light pollution is a real problem for most people, but some great shots can still be had in town. If you can get yourself about 30 miles away from any town or city, you should find life a little bit easier. There are lots of online light pollution maps to help you find somewhere local, or use it as an excuse to take a holiday somewhere remote! I do most of my practise from my driveway, and we live in a town quite close to London, and have a street light right outside. I still managed to get this lovely shot of Cassiopeia and the Andromeda Galaxy (it's small!) though, so starting out in your garden is often a really good place to begin. 

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Focusing

Having set up you camera on your tripod, and framed your composition, you need to focus. This is the part many people find the most difficult. Set your camera/lens to manual focus. Focus on infinity if your lens/camera has a scale. For some old manual lenses they have a "hard stop" at infinity, others don't. If you are struggling, the easier thing to do is to focus on something far away during the day using autofocus, switch to manual focus and then tape the focus ring in place. If you can spend time practicing focusing on the stars, so much the better. Below are some massively magnified photographs of what in and out of focus stars look like. If the centre of the star appears dimmer than the outer parts, then it is out of focus.

Definitely out of focus...

Definitely out of focus...

Super close-up of a star, still out of focus though

Super close-up of a star, still out of focus though

Super close-up of a star, in focus!

Super close-up of a star, in focus!

Exposure Time

Now we need to head down a road paved with science. Are you sitting comfortably? The stars in the night sky are in a fixed position, but the earth is rotating, which makes the stars appear as if they are moving across the night sky. It is all very pretty, but the effect is that the long exposures needed to capture the very dim starlight means they start to trail. If you are after a nice long star trail, then that's fine, but often you will want pinpoint sharp stars. To calculate the exposure you can use a series of different equations, relating to the position of the stars in the night sky. To get you in the right ballpark, use the rule of 500:

Rule of 500: t = 500 / f
t = exposure time (s)
f = full frame focal length (mm)

It is likely you will need to adjust the exposure time based on the light pollution and to suit your specific camera set up. There is a lot of trial and error to begin with until you learn how you camera captures the small amounts of light in astrophotography. 

ISO, F Number and Other Settings

Choose as high an ISO on your camera that will still give you an image which is acceptable in terms of noise. This varies massively with the camera and sensor. For my Fuji XT-1 I can happily use up to an ISO of 3200, but generally shoot on 1600. 

Open your aperture as wide as it will go. Some lenses have very bad vignetting or lens aberrations which don't show up in daylight, but will make stars look like comets at the corners. If you have this problem stop down 1 or 2 stops as that normally helps.

I tend to leave White Balance on auto. I also leave Noise Reduction on. For long exposures, most cameras will take the photograph, and then take a second shot, but this time without exposing the sensor to the light. The camera can then identify any noise being generated by the camera itself. This is known as a dark frame, and the camera then subtracts the dark frame from the light frame, removing some of the noise. It's clever stuff, and you can do this outside the camera in specialist software if you wish. 

Post Processing & Advanced Techniques

You are likely to need to post process your image, I use Lightroom. There are number of post processing and advanced techniques to reduce noise and really bring out the subjects, but that's for another blog post. For now, import your image and have a play with the exposure and contrast which will help a lot. 

What to Photograph

Here are a few ideas to get you going:

  • Orion is particularly good as it is easy to spot
  • Cassiopeia - If you capture Cassiopeia, you may well also get the Andromeda Galaxy. You won't be able to see it with the naked eye, but it will show up in your photographs. 
  • The Moon - The moon is great to photograph. Pop a telephoto lens on your camera and away you go. You will need a faster shutter speed as the moon is really bright compared to everything else. I normally start at 1/60sec.
  • General starscapes - If you have a nice landscape you enjoy shooting in the day, try it at night and see if you can fill the sky with stars. 

If you do have a go at shooting the night sky, I'd love to see your photographs. Tag me on instagram (@helenfennellphotohgraphy) and use the hashtag #astrophotojoy. Happy shooting and may your nights be forever cloudless!