Few subjects are as captivating as the stars, so it’s easy to spend hours gazing at them. Find out how to capture astro images loaded with detail.
If you’ve ever tried to take a picture of them using the automatic mode on your camera or phone, doubtless you’ll have been disappointed with the results. Creative cameras with manual MASP modes, such as DSLRs, have the ability to capture a much higher level of detail than the human eye. But they do need to be set up correctly to do the night sky justice, so stabilising your camera with something like a tripod is essential for this technique.
Dark Sky areas
The night sky can look very different depending on where you are on the planet, as you’ll be able to see different star constellations. The southern hemisphere also gets a much clearer view of the Milky Way, so places like South America and Australia can be particularly good for these kind of shots. Regardless of where you are, you’ll want the sky to be as dark as possible.
A dark sky area is one that is far away from the light pollution of city street lights, as this light will bleed into your shots, reducing contrast and star visibility. There are loads of dark sky maps online showing you where these dark pockets are. In England, places such as Kielder Forest in Northumberland become fantastically dark in the evenings. You can also use apps such as Star Walk 2, which show you where specific constellations are, as well as where the Milky Way sits in the sky. This particular app also informs you of special celestial events such as meteor showers.
Set your camera up on a tripod and compose your shot. Focusing can be tricky as there is little light, but if you place your active AF point over a star it should be bright enough to lock on to. If the autofocus keeps hunting back and forth, don't worry. Go into your camera’s Live View mode and zoom in on the screen view so you can clearly see how sharp the focus is. Put your camera or lens into manual focus and adjust the focusing ring until the stars are pin-sharp.
Go into your camera’s manual mode, set an ISO of 800 to begin with and open your aperture as wide as it will go. This is usually f/3.5-5.6 on a kit lens, but if it will open further that’s even better. Shutter speeds will vary between 5sec and 15sec, so start with a 10sec exposure as your first test shot. Set the 2sec self-timer so you don’t jog the camera and start the exposure. Alternatively, you can use a shutter release cable.
Take a look at the shot on the back the back of the LCD and if it’s too bright reduce the shutter speed a little. If it’s too dark, increase the ISO and shutter speed a little until the exposure looks right. Make sure you don’t set a shutter speed longer than 15sec, as after this your stars will turn into long trails rather than sharp pinpoints of light. This is because the Earth’s rotation is more noticeable in these longer exposures.
Step-by-step - How to edit your star shot:
1. Tweak the RAW
Make sure you shoot in the RAW format, as these files hold much more data – very handy for star shots when you need a broad range of tones, from the deep black sky to the bright stars. In your RAW editing software increase the exposure a little until you’re happy with the result. Push up the shadows and decrease the highlights to preserve detail in the darkest and brightest areas of the shot.
2. Dodge and burn in Photoshop
Having a good level of contrast between the bright stars and dark sky is crucial for creating a great astro pic. In Photoshop you need to use the Dodge and Burn tools to selectively add these pockets of contrast. Start by clicking on the Burn Tool to make it active and in the Tool Options set the Range to Highlights and the Exposure to 3%. Make sure the Brush is soft so you can apply the effect gradually. Now brush over the areas of the sky you’d like to darken and keep painting over them until you’re happy with how dark they appear.
Then switch to the Dodge Tool. Keep the settings the same as before, but this time set the Exposure to Midtones and paint over the parts of the sky you’d like to brighten. This includes the horizon, stars, foreground and Milky Way. Finally, set the Exposure to Highlights and paint over the stars to make them really pop. You can switch back and forth between the Dodge and Burn tools until you’re happy with the result.
Dan Mold is a professional travel and wildlife photographer and a regular contributor to Practical Photography and Digital Photo. He has recently returned from an epic adventure around Asia and Australia. See more of his work here.