Shooting stars
Our Apprentice shoots the Milky Way above neolithic ruins with astro-expert
When Josh and Brian met amongst the neolithic standing stones at Avebury – home to the largest stone circle in Europe – the hardest part of their astro photo shoot was already over. Careful planning (and a strategic postponement) had rewarded them with clear skies and a new moon – ideal conditions for shooting the Milky Way.
But weather isn’t the only consideration astrophotographers have to make when planning a shoot. Light pollution can have a huge impact on the visibility of the night
sky and while human expansion continues to overlook the effects, a growing number of the world’s dark skies are at risk.
“Avebury is such a great place to shoot,” explained Josh. “The standing stones make ideal foreground subject matter and while we’ll have to deal with a small amount of light pollution, the area boasts some really good dark skies too.”
The ancient landmark comprises two small stone circles surrounded by a large outer circle. Having arrived before sunset to scout out the best locations, the photographers headed to the southern inner circle first.
CORE TECHNIQUES
Josh pointed at a passing car: “The road that passes right through the middle of Avebury makes for a more challenging photo opportunity. Obviously the later you shoot the less busy it is, but we’ll definitely encounter a few headlights.”
The pair set up and chatted while civil twilight gave way to nautical twilight as the sun dipped well below the horizon and stars began to clearly populate the sky. However, it would still be a while before the Milky Way was clearly visible.
Josh pulled a smartphone from his pocket and opened Photopills. Using the phone’s camera to display a live view of the area, the app’s Night AR function overlaid an image of the Milky Way exactly where it was positioned in the sky. “Augmented Reality has really changed the way many of us approach astrophotography,” explained the pro, “but you can also use an asterism called the ‘Summer Triangle’ to locate the Milky Way.”
He pocketed his smartphone and pointed at the night sky. “It comprises these three stars: Vega, Deneb and Altair. The Milky Way appears to pass right through the triangle formation.”
With a good idea of the Milky Way’s position, Brian adjusted his framing using Live View. The Apprentice zoomed into his Nikon D7500’s rear LCD and used the D-pad to find a bright star. He then manually focused by carefully turning the focus ring. “That’s perfectly sharp,” said Josh, “and it’s great that you’re using Live View, I wouldn’t recommend focusing on a star through a DSLR’S viewfinder.”
The pro noted it didn’t matter what star was used, but identified the astronomical object as Antares. “Now you’ve focused on the night sky, you can adjust your ballhead to recompose the image.”
The next step was to capture a test shot using a wide-open aperture and a superhigh ISO. “Obviously it’s far too overexposed and noisy to actually use, but it shows very clearly the current composition,” explained Josh. The test shot revealed the nearest standing stone was slightly cropped out, so Brian adjusted his framing accordingly.
Brian had started shooting at ISO800, but as the light diminished further Josh suggested he push the camera’s sensitivity setting to ISO3200 and opened the aperture to gather as much light as possible. This resulted in a 20-second
shutter speed. “That’s good,” said the pro. “Anything above 20 seconds and you’ll start to get star trails as the stars blur due to the Earth’s rotation.”
Brian kept shooting and timed his shots between the headlights of passing vehicles. When Josh was satisfied they’d landed enough images of the Milky Way he turned their attention to the standing stones in the foreground.
He walked right up to the nearest stone and shone a bright white light on it. This gave Brian a reference point in which to focus. When they reviewed the shot in Playback Josh pointed to the standing stone. “Notice our shadows cast on its surface? The culprit is the light outside the Red Lion pub, it’s pointing directly at us.”
The solution was for Brian to fire the shutter and for the pair of photographers to walk in a large circle for the duration of the exposure. “That’s done it,” said Josh, “by moving during the long exposure we’ve simply blurred out our shadows.”
With the help of Josh’s torch, Brian focused on a stone in the midground and captured a few more images. Super Shot #1 would be an eight-shot composite comprising a six-image foreground and two-image background.
STONE SHADOWS
As the pair walked towards the northern inner circle to capture the next shot, Josh and Brian discussed the best time to photograph foregrounds. “You can photograph your foreground at dusk and blend it with the night sky later,” said the pro. “The lighter conditions will allow you to capture more detail, but it won’t look as natural as if you capture the foreground and background together.
“As a night sky conservationist I want to capture images that are as natural as possible, but at the end of the day it’s entirely up to you.”
The photographers entered the field that contained the ruins of the northern
inner circle and set up their tripods. Once again an outside light from the Red Lion partially illuminated the scene, only this time it was much brighter and hitting Brian’s camera side on.
“We can fix that by placing the tripod behind that stone,” said Josh as he pointed towards a stone that blocked the light. Brian moved his tripod into the shadow. Once again he dialled in a high ISO and took multiple test shots before adjusting the framing. He eventually settled on a portrait orientation composition and Josh was pleased to see him use the Virtual Horizon to level out the frame.
“That looks good,” said Josh. “Just be mindful that your controls have been turned 90-degrees anti-clockwise, which makes it even harder to operate in the dark.” Once again Josh shined a torch on the subject so Brian could find focus. “The light from the pub will essentially light paint this stone,” said Josh.
“Won’t the scene look more natural without artificial light?” asked Brian.
“Definitely,” said Josh, “but light pollution is something we live with and I don’t try to hide it if it’s there. It highlights the importance of preserving our dark skies more than ever.”
Brian dialled in his exposure settings and began taking test shots, but the photographers were soon interrupted by some unexpected visitors. “We’ve made a couple friends,” chuckled Brian as a pair of sheep emerged from the darkness and threatened to encroach on his shot.
Josh stood between the inquisitive animals and his Apprentice and they soon lost interest, but Brian was facing another problem – dew was beginning to form on his lens. Josh carefully wiped the element with a cloth. “I use a circular motion to help prevent smearing the glass,” he said before retrieving a dew heater from his bag and wrapping it around the lens. “That should prevent it from steaming up again.”
An aperture of f/4 and ISO3200 provided an exposure of 15 secs and the light from the pub helped the standing stone pop against its dark surroundings. Four shots were blended together to create Super Shot #2.
STACKED SHOTS
They headed to the northwest sector to shoot the outer stone circle. This time Josh suggested that Brian set up very close to the standing stone so it occupied a much larger portion of the shot. “We can create a bigger depth of field by capturing multiple shots of the subject while focusing at different points and then stacking
those images in post,” explained the pro.
“Light pollution from that building over there is really encroaching on the photograph,” said Brian as he pointed towards a nearby barn.
“Let’s simply move around the rock until the light isn’t in the frame,” replied the pro.
Brian began inputting his camera settings, but the exposure was too long to capture the stars crisply. Josh checked the time: “Around the summer solstice it never gets completely dark. You still get a faint glow on the horizon, but we’ve moved into astronomical twilight now, which is as dark as it’s going to get.” He suggested pushing the D7500 to ISO5000, which allowed Brian to shoot a 20-second exposure.
With no surrounding light hitting the stone, Josh suggested using light painting to illuminate the subject. As Brian focused on the stone and eventually initiated the exposure, Josh used the torch on his smartphone to illuminate the rock, carefully moving the light over every part of the neolithic feature.
The pro noted that clouds were beginning to appear in the sky and consulted a weather app. “It’s coming in fast,” he said. “What we can do is implicate similar methods to daytime long-exposure photography. Clouds in the night sky blur,
just like they do in long-exposure landscapes.” Super Shot #3 was a five-shot composite, with three images used to create the foreground and two images to form the night sky.
STAR TREKKIN’
Much of the night sky was obscured by clouds and the pair’s options for the final Super Shot were limited. “Shooting towards the north is our only chance now,” said Josh. The photographers headed back to the southern inner circle, via Brian’s van, to pick up his star tracker.
“This will allow us to shoot well beyond 20 seconds and really blur those clouds,” said Josh. Brian fixed the star tracker to a sturdy-looking tripod, which gained the pro’s approval: “Travel tripods are great if you’re on the move, but for astro you want a really substantial tripod that isn’t going to move during long exposures.”
The first step was pointing the star tracker towards the north star (Polaris). Josh knew exactly where to look, but noted how inexperienced astrophotographers could learn the night sky using an app such as Star Walk. Next, they used the tracker’s built-in bubble level to ensure the head was perfectly even and then set the latitude indicator accordingly.
The tracker’s positioning was refined by looking through the polar scope and using the reticule to line up Polaris, found at the tip of the Ursa Minor constellation. “Polaris doesn’t point 100% north,” explained
Josh, so he offset the polar scope slightly to place the star at a 10 o’clock position.
With the star tracker perfectly aligned, Brian fixed the ball-head attachment and mounted his camera. He then turned the Mode Dial to celestial tracking.
“Now the tracker’s aligned, you can tilt and pivot your camera on the ball head wherever you want, not that the clouds are giving us many options,” said the pro.
The plan was to photograph a portrait orientation image of a standing stone with the night sky and blurred clouds behind it. “Won’t the star tracker blur the foreground as it moves?” asked Brian.
“Correct,” said Josh. “We’ll use a shorter exposure to photograph the foreground and then we’ll dial in our super-long exposure for the background.”
Brian used a 25-second exposure to capture two images of the foreground before dialling in a near two-minute exposure at ISO400 to capture the sky. Without the star tracker this would have captured short light trails, but with the tracker perfectly aligned he was able to capture lots of movement in the clouds and tack-sharp stars.
“That’s Super Shot #4!” said Brian. “And just in time too,” chuckled the pro as the cloud cover settled in for the night.
BRIAN’S COMMENT The standing stones are amazing subjects and we got a great view of the Milky Way. I’m now much more conscious of light pollution and know my way around my star tracker, which will really up the quality of what I’m able to capture.
JOSH’S VERDICT Brian has a really good knowledge base when it comes to astro. He had no problems focusing manually and made great compositional choices, but he’s more aware of light pollution now, and better equipped to work around it.