Astrophotography: How to shoot the night sky

Libby Plummer
Yahoo News.
Long exposure taken with Sony Alpha 7S camera, showing the astrophotography setup

For those of us living in large towns and cities, we rarely get to see the stars due to round-the-clock light pollution so it's often assumed that photos showing spectacular starscapes have been produced in Photoshop. However, as the stunning pictures of the recent Geminids meteor shower prove, it is possible to capture incredible starscapes on camera, just as long as you step away from the street lights.

Professional snapper Andrew Whyte (@LongExposures) makes a living from doing just that - he's one of the UK's leading night photographers and is also well known for his quirky Lego man photos. We tagged along on an astrophotography shoot with him to learn how to shoot the night sky.

Where can I shoot the night sky?

While it's possible to shoot the night sky in the UK, plenty of preparation is needed and that all starts with the location. Wide-field astrophotography - which involves capturing the night sky with a normal camera, without the need for a telescope - requires a location that's largely free of light pollution.



These areas are known as 'dark sky' sites and can be found all over the country. It's also a good idea to research the area and find out about any features - like buildings and monuments - that can be used as a foreground to your starry backdrop.

Long exposure with star trails taken with Sony Alpha 7S camera. (Libby Plummer)


We took our shots around Douglas on the Isle of Man, but you can find out which sites are closest to you with a quick internet search. Dark Sky Discovery is a useful place to start.

It's also important to check the weather, as too much cloud cover will prevent you from seeing the stars at all. Andrew Whyte pro snapper Andrew Whyte, who specialises in long exposure photography which includes astrophotography and lightpainting, offers some advice:

'I've found XCWeather to be fairly reliable for forecasting cloud cover, and timeanddate.com provides my lunar phases and timings. A guy known as @VirtualAstro does a great job of updating Twitter with information like the times of the International Space Station passing over and aurora alerts'.

What kind of camera do I need?

While most cameras offer a range of pre-set shooting modes with some even including 'night sky' options, you really can't hide behind these when it comes to astrophotography, says Whyte.

He argues that you really need to get to grips with your camera's manual settings to get good results. But what qualities do you need to look for in an 'astro' camera'? Whyte explains:

'Ultimately what makes a good camera for astro is image quality. Current models with a high ISO range, like the Sony Alpha 7S, which has a range of 40-409,000, are especially well suited to low-light photography. This particular camera also has a full frame sensor which is good for dimly lit conditions'.












Camera with a high ISO range, like the Sony Alpha 7S, are ideal for astro shots (Sony)

ISO refers to the camera's level of sensitivity to light. Each step up the scale doubles the sensitivity so that a setting of ISO 400 is twice as senstive as ISO 200. Generally speaking, the darker the shooting conditions, the higher the ISO rating you need. It's best to start on as low a setting as possible - try ISO200 - then adjust as required.

Working in the dark means it's also good to go for a camera with good physical controls, rather than having to rely on the screen, says Whyte:

'On a practical level, it's also better to be able to make adjustments physically - the A7s has shutter speed, aperture and ISO rating available through the physical thumbwheels and dials, rather than having to delve into the onscreen menu to find them and momentarily lose some of your night vision.'

You'll also need to think about which lens you use:

'The most compelling widefield astro images are those which portray an earthly landmark or landscape against the expanse of the night sky. An ultra-wide angle lens (14-20mm full-frame; 10-15mm crop sensor) provides a significant field of view to record grand vistas, and reduces the challenge of keeping everything in focus. To show the sheer size of the Milky Way in a single frame, this is your best bet.

'When I'm researching a location I quite often find myself looking at the settings of other people's pictures on Flickr to find what lenses they used to get a particular perspective - it helps to know what equipment to pack, and also to pre-visualise which areas of sky I'm likely to record in my final image.'  

Do I need anything other than a camera?

Obviously you'll need a decent camera, but what else should you invest in? There are a few basics that you need to think about, but the good news is that most of them don't cost much. The only other real expense is a tripod, which is essential as there's no way that you'll be able to hold your camera still enough for long exposures. A cable release, which acts as a remote control for your camera is also preferable to stop you from jogging your camera when firing off a shot.













Long exposure taken with Sony Alpha 7S camera, including light painting effect (Libby Plummer)


A torch is also a must-have - not only because you're likley to be trekking around in complete darkness, but also to frame the corners of your shot. And at the risk of sounding like your mother - you need to wrap up warm. You'll be shooting at night, probably in a wide open space, where you won't be moving around much. Plenty of layers, thermals, a hat, gloves and extra socks are all absolutely essential.

Whyte runs us through a couple more of his must-have pieces of kit, explaining:

'I use glowsticks to help locate the camera, either when lightpainting or if I leave the equipment running while to go and find a vantage point for the next shot. An unwanted side effect of working in the dark is that it's easy to break stuff.

'I also use gaffer tape and cable ties to help with running repairs, but they can also help prevent camera straps flapping in the wind, or hold a torch in place. More than once I've created a makeshift cable release with gaffer tape and a small stone taped over the shutter button...'






Long exposure taken in Northumberland with the Sony Alpha 7S camera (Andrew Whyte)

What settings should I use?

Astrophotography is largely about letting as much light into the camera as possible so you'll want high ISO settings and a wide aperture, ideally both.

We've already covered ISO, but if you're confused about aperture, this is basically the opening in the lens through which light is collected when you take a photo. You can adjust the size of it depending on how much light you want in your shot. Slightly confusingly, the lower the F/ number, the bigger the aperture is and the more light it can let through. For example - a aperture setting of f/2.8 would give an extremely wide aperture - ideal for shooting at night.



Long exposure shot showing star trails (Andrew Whyte)


After ISO and aperture, the third pillar of photography is shutter speed, which controls how long the camera's shutter is open for and in turn, the amount of ambient light in your shot. For astrophotography, it's best to keep exposures as short as possible to get clear stars in your image. Using longer exposures will cause star trails to form in your image, caused by the rotation of the Earth while you're shooting - which can also make for a great shot.

Long exposure taken with Sony Alpha 7S camera, showing the night sky (Andrew Whyte)

If you're shooting a landmark like a building or rocks in the foreground, then a torch is useful to shine some light on it to give the camera's autofocus something to hook onto. The torch can also be used to locate the bottom corners of your shot - essential when you're working in almost total darkness.

If all this sounds a little baffling, the good news is that Whyte has put together an astrophotography cheat sheet for beginners, explaining the different settings you'll need for different shots.

Once you're all set up, you can go ahead a take a test shot. There's a lot of trial and error involved in shooting the night sky, so you'll probably need to tweak the settings after each shot. The cheat sheet above also includes a troubleshooting guide on what to change to improve each shot.

What do I do once I've taken my photos?

No matter how good your photos are, chances are you'll need some form of editing to get the best results. You can carry out basic editing using free software like Apple's iPhoto for Mac, but if you're serious about your snaps then you might need to cast your net a little wider, suggests Whyte.

'There's a fantastic program called StarStaX which I use to compile my startrail images. It's fast, multi-platform, intuitive and free! It automates the task of layering lots of individual frames to create a 'stacked' startrail image.'










Astro expert Whyte, summed up the basics for us - here are his top tips for astrophotography:

Preparation - find a location that's dark enough for good astro viewing. That means away from direct illumination and preferably a long way from the glow of city lights. Refer to weather forecasts and lunar timetables to best understand what conditions will be like. A hat & decent boots will help keep you productive when cold or tiredness strikes.

Patience & perseverance - it takes time to set up a shot and they often don't work out as planned first time. Keep tweaking your framing and settings to get a result until the picture on your camera screen is what you're after.

Stability - a sturdy tripod is the foundation of a sharp image and its significance can't be overstated. Use the remote control cable release or a delay timer to avoid vibrations when triggering each shot. Switch off any image stabilisation or vibration reduction systems - these actually work against you when the camera is tripod mounted.

Focus - Use a torch to illuminate your subject and make it bright enough to focus on. I recommend using autofocus on this brightened subject but check that you have sufficient depth of field to keep the stars sharp, too.

Detail - Silhouettes can be very dramatic but don't shy away from adding your own torchlight to bring detail into the foreground. Step away from the camera and light from one side or the other to add depth. You won't need a lot of illumination if shooting at high-ISO ratings/ wide aperture so don't overdo it.