atmosphere

Prepare yourself to capture the meteor shower from Halley's Comet's impromptu fly-by

Halley's Comet made its last swoop past earth in February 1986. I remember it well because I was in primary school at the time, learning about the Norman Conquest. In addition to the boos, hisses, and cheers elicited by the key players and the confusion surrounding Harold Godwinson's death, Halley's Comet plays a starring role in the Bayeux Tapestry, which documents the invasion of a loosely termed 'England' by William of Normandy and his cronies. That we had the opportunity to experience the same celestial phenomenon as the people we were learning about, all of whom lived 900 years before us, was rather special. The timing could not have been better for a memorable series of lessons. Halley's Comet blazing a trail across the Bayeux Tapestry (image courtesy of Wikimedia)

Seeing as Halley's Comet is on a 76 year schedule, it isn't expected again in all its glory until July 2061; however, we are being treated to an impromptu meteor shower in the next few days. The comet is likely to deposit a trail of cosmic dust into our atmosphere on 21 and 22 October 2014, giving us a shooting star display visible to the naked eye.

If that isn't an excuse for trying a little night photography, I don't know what is. So apart from the hoping for clear skies, what else can you do to maximise your chances of capturing the tail lights of Halley's Comet?

The basics

Whatever means you use to take your photos, capturing a meteor shower is fundamentally the same process: shooting a series of long exposures. There are a few options for how you go about it, but once you know that bit, it's fairly simple.

Location

The darker the sky, the better the chance you will have of being able to see the streaks of light as the comet's dust burns through the atmosphere. Ideally, then, you need to be somewhere that doesn't suffer from too much light pollution and has an uninhibited view of the sky. Open and accessible heath- or park-land that's relatively far from city lights is ideal; just be certain you're not venturing somewhere you shouldn't, either because the land is privately owned or you're disturbing a sleeping bull! I'd advise not going alone, either. Shooting in secluded or isolated locations is not necessarily a solitary activity.

Equipment

Shooting the night sky means long exposures, so you're going to need a tripod, and an intervalometer will ensure the best results, although you can get by without one. Naturally we recommend Triggertrap, especially because its star trail mode makes life easy, but your mileage may vary. For your lens, a fast, wide-angle lens is advisable. You're never quite certain where they'll start or where they'll end, so the wide-angle provides you with sufficient flexibilty, and it gives you the option to introduce an interesting foreground to the shot, too. The darkness of the sky means that you need fast glass to let in enough light. And an empty memory card is a good idea: you'll be taking a lot of images.

The set up

While shooting stars can turn up anywhere, they are most likely to cluster around a single point called the radiant. Don't aim your camera directly at the radiant, when you've worked out where it is, but about 45° to one side of it. You also want to compose the frame so that it is visually interesting beyond just the shooting stars. Think about including something intriguing in the foreground. Turn off the auto-focus, use as wide an aperture as you dare—you might not want it all the way open for sharpness—and focus to infinity.

The best option to photograph a meteor shower is very similar to capturing a star trail image, when you compile a series of long exposures shot over a significant period of time into a single image, but with a few key differences. You can read our star trail tutorial here, and if you'd like to shoot a star trail image that hopefully captures some shooting stars, go right ahead. Otherwise, you can tweak the process and use it as the basis to capture a series of photos from which you'll select the ones that show shooting stars streaking across them.

Star trails by Thomas Langley (thanks to Triggertrap)

What are these tweaks you'll need to make, then? First and most obviously, you'll not compile all of your frames into a single image that charts the movement of the celestial bodies across the heavens. Instead, you'll pluck out the indvidual images displaying shooting stars, or maybe composite several images showing shooting stars.

Second, you might need to use a slightly shorter shutter speed than you would with a star trails sequence, to ensure that you don't capture the turn of the earth. With a star trails shot, the movement of the earth is exactly what you want, but with single meteor images, not so much. Between 10 and 25 seconds is recommended, but a few test shots should help you to decide what you need to use. This slightly shorter shutter speed will require you to adjust the ISO to get a good exposure, too.

Finally, you can chance not taking your series of images with very short intervals between them, as you would with a star trails sequence, but leave the gaps a little longer. That means you might miss a few opportunities, but the law of averages suggests that if you shoot over a period of a few hours, the odd photo will have a shooting star zooming across it.

Choose your exposure time, number of exposures, and the interval between them

When you have set the focus and established your shutter speed and ISO, you will need to set your intervalometer as you would for a recording a time-lapse sequence, using the exposure time that worked best in your test shots. If you're using Triggertrap's star trail mode, set the exposure time that you established in testing with your chosen interval between frames, and select the number of frames you want to take. With a slightly longer interval between frames, say five or ten seconds, you could shoot for hours!

If you don't have an intervalometer, there's no reason why you can't try your hand at meteor shower photography. Instead of relying on a remote triggering device to release your camera's shutter, you'll be doing it yourself, which might get tiresome. Just as you would with a star trail-based sequence, aim your camera in the right spot and focus to infinity. With your camera in manual mode, use the widest aperture you can, select a shutter speed between 10 and 25 seconds, adjust the ISO accordingly, and press that trigger. Over, and over, and over, again!

Remember to keep warm, and here's hoping for clear skies.