In pictures: Hong Kong photographers show how to shoot night skies over city
We talk to two local experts on astrophotography who share tips on getting the best pictures of stars, galaxies and nebulas in our light-polluted city (and elsewhere)
When it comes to the galaxy we live in, travel photography doesn’t even require leaving home. Social media is flooded with all kinds of contrasting images of the night sky and the Milky Way, but they all have two things in common; patience on the part of the photographers, and – whisper it – some fairly simple photographic techniques. Taking images of the night sky really only requires four things: a DSLR (or compact camera with manual exposure), a tripod, clear and dark night skies, and dedication.
“For most of the time I use an ordinary DSLR and a sturdy tripod,” says Timmy Wong, a Hong Kong-based landscape photographer and astrophotographer (timmywongphotography.wix.com/timmywongphotography). A tripod is critical because the camera shutter needs to be left open for about 25 seconds. Any longer and the earth’s rotation will make the stars blur. Any shorter and not enough light will get in.
Using your widest angle lens, position the camera and tripod away from direct light, choose manual mode, then set the focus to infinity (or shine a bright flashlight on something about 20m away, auto-focus on that, then switch to manual focus). You can start with ISO 800, open the aperture as much as possible (f/2.8 or so, depending on the lens), and take an exposure for between 15 and 25 seconds.
Using a shutter release cable, remote control or your camera’s self-timer function will help reduce camera shake and blur. If you have a high-end DSLR, use a higher ISO and decrease the exposure time, but it’s always a question of balance and experimentation. “I use ISO 800 to 6400,” says Mew Chu, an amateur astronomer who conducts creative night-sky photography courses in Cantonese around Hong Kong. “Due to the dim starlight it’s very helpful to have a high sensitivity.”
You don’t have to travel far to get the right conditions for astro-photography. Getting away from light in Hong Kong isn’t easy, but it is possible. “Sai Kung High Island Reservoir, the south of Lantau Island, and outlying regions like Po Toi Island are ideal for shoot the stars,” says Chu. Hong Kong Space Museum’s Astropark, near the High Island Reservoir, has stargazing facilities and is a fine place to practice astro-photography. “Shek O Country Park is more convenient, but light pollution is very serious and deteriorating,” says Chu, adding that even Plover Cove, once a famously dark area, is now subject to light pollution from development at Ma On Shan, and is now barely darker than the city.
While light pollution is a concern to anyone interested in the night sky, it doesn’t rule-out astro-photography. In fact, shooting the stars from within the city can lead to dramatic images. “I like taking night sky photos in suburban areas as I can put both the sky and the city lights into my composition, though it’s really challenging,” says Wong.
For Wong, whose favourite dark sky location of all is Galloway Forest Park in Scotland, a good night sky photograph is as much about composition as any other landscape photo. “Looking for foregrounds like waterfalls, rivers or even cliffs definitely increases the attractiveness of the composition,” he says. His winning entry in the Astronomy Photographer of the Year 2015 competition was taken at Sunset Peak on Lantau.
Chu is more interested in capturing specific constellations, so he adapts his composition accordingly. “I use a lot of low-angle shooting techniques, often lying on the ground because the stars are then easier to see,” he says. “I often teach the public about the stars, so I compose for the sky, and for the best angle to look at the stars.”
Although any image of a famous landmark or attractive composition with stars in the background can be awe-inspiring, there is one image that astro-photographers travel the world to capture; the Milky Way. Our own galaxy, home to at least 100 billion stars, is visible from earth as a dramatic arc across the night sky from northeast to south, but only at certain times of year. “The perfect time for photographing the Milky Way in Hong Kong is during the summer,” explains Wong. “We get clearer skies, and the bright core – which is the central bulge of the Milky Way, only displays in the summer night sky.”
The Milky Way can be glimpsed at other times of the year from the northern hemisphere, but only on moonless nights between July and September can that fabulous core be seen, and here it helps to know a few basic constellations and asterisms to decide exactly where to point your camera. If you look east after dark on a summer night anywhere in the northern hemisphere you’ll see the Summer Triangle, the three bright stars of Vega, Deneb and Altair. Any planetarium app, such as Star Walk 2, Sky Map or SkySafari, will help you identify them. Running from Deneb through Altair should be the Milky Way, with the richest, brightest section beneath, behind the constellations of Sagittarius and Scorpio. “My favourite is Scorpio, its tail is the most spectacular part of the centre of the galaxy, for viewing or photographing,” says Chu.
Rich in star fields, nebulas and bright globular clusters, this area of the sky is a real hotspot for night sky photographers. “When I am taking still Milky Way shots, I normally use an ultra-wide angle lens and with the settings of ISO 3200, f/2.8 and 30 seconds exposure,” says Wong, who also uses an equatorial tracker that follows the rotation of the planet, thereby allowing much longer exposures. “If I use a tracker, the settings are totally different, maybe ISO 800, f/3.5 and perhaps a four-minute exposure,” he says, adding that imaging editing software like Photoshop and the astrophotography-centric PixInsight are useful for enhancing images. “I tend to give a cool blue tint to the sky and this gives a higher contrast to the orange-yellow dusty Milky Way,” he says. Chu prefers Lightroom, principally for the noise reduction and colour temperature tweaks it allows, though he underlines how important it is to take all night sky photographs in the RAW format, which makes post-processing much easier.
Another favourite shot among astro-photographers is the star trail, where the camera continually takes 30-second exposures, without moving (or even touching) the camera or tripod, for at least 40 minutes. Those images are then digitally ‘stacked’. If you point the camera to the north, the result is circular trails that vividly demonstrates the Earth’s rotation. “For star trails, multiple exposures require software for post-processing, such as StarStaX for Mac and Startrails for PC,” advises Chu.
The time of year makes a big difference to what is visible in the night sky, so does your location on the planet. Move south towards, or even below, the equator and the Milky Way gets more and more prominent. However, when it comes to the universe, there’s no place like home. “I shoot stars all over the world, but I would still choose Hong Kong as my favourite place, because this is my home,” says Chu, who recently travelled to Mongolia to photograph the night sky. “Hong Kong has the world’s most famous urban light pollution, and the stars are slowly disappearing in my generation … with my photographs I want to evoke the forgotten starry night.”