In astrophotography, the sky is the limit.
That’s something Josh Knutson repeated a few times while describing how he manages to capture images that are — pardon another pun — truly stellar.
Astrophotography is a way of capturing colorful photos of nebulas, planets and stars. And it is just like regular photography, just a whole lot more complicated.
At sunset on April 16, Knutson and his 8-year-old daughter, Aurora, loaded up a Jeep with some of those gadgets. They hauled telescopes, cameras and boxes of electronics down the sandy back roads and arroyos of northern Rio Rancho, hunting for darkness.
Now that people have migrated north of Albuquerque, local light pollution is more and more of an issue, Knutson said. And the orange glow of Albuquerque has always been a problem.
“That’s my biggest frustration,” he said. “A single neighbor’s light is enough … but you’ve got millions and millions of bulbs. That dome (of light from Albuquerque) can be seen for 60 miles out.”
Despite those challenges, Knutson has a good handle on his craft. His photos tend to make their way around the Internet. You can find them in Astronomy Magazine’s Astronomy Picture of the Day, the National Geographic website and quite a few of his photos are used to sell the various astronomy gadgets Knutson uses.
After some searching, Knutson parked the Jeep in a slight depression in the desert landscape. The bright moon, of course, was still a problem, but there isn’t much that can be done about that, he said.
He unloaded his gear, setting his laptop on a small stand, erecting a sturdy tripod and then mounting a Polarie Star Tracker on the tripod.
The Polarie is a white, smooth device that looks a little like an over-grown iPod. In the hands of a good astrophotographer, it can be set to track the moon and stars.
Knutson sets a finely-calibrated lens to the right day and month, then uses it to sight Polaris and align the star tracker.
When set at the proper angle, the device slowly rotates to compensate for the movement of the earth. So when Knutson aims his camera at the Milky Way and sets the camera for a 10-minute exposure, he won’t have a big, blurry smudge instead of a cloud of stars.
With a long exposure, he said his camera can collect more light than a person could ever hope to see, even through a powerful telescope.
He mounted a relatively inexpensive Canon digital SLR camera to the star tracker. Knutson is well past the point of voiding the camera’s warranty, he said. He’s torn it apart, removed the infrared filter, put it back together and turned it into what amounts to an extremely specialized web-cam for his computer.
After setting his camera up and plugging it in to the computer, Knutson announces that he is ready to collect images.
Meanwhile, Aurora has been busy finding the moon through the eyepiece on her telescope — about as tall as she is — and has taken a half-dozen photos using a point-and-shoot camera.
“It really is a big telescope for me,” she said. “I used to have a smaller telescope and I couldn’t see a lot of things that well.”
Even though her technique is not as sophisticated as her father’s, one of Aurora’s photographs recently won her a little attention when a shot she took at Chaco Canyon of a solar eclipse was published at an astrophotography website. That’s a good start, she said.
“I really want to be an astronomer someday,” she said. “That means I’m on my way.”
Satisfied with the night’s work, Aurora packed up her camera, climbed back into the Jeep and fell asleep.
Knutson, meanwhile, continued to adjust the exposure for a picture of the constellation Orion. The colors in constellations and deep-space objects will only emerge if the camera can soak up a lot of very, very faint light, he said.
Some of the light Knutson is trying to capture is so faint it only comes in a few photons at a time. Those tiny “packets” of light are an effect of how the world works at a very small scale, as described by quantum mechanics. For Knutson, that aspect of physics, quite simply, is just another barrier between him and the image he wants to capture.
One of the ways Knutson overcomes those issues is by using 60 or more images of the exact same patch of sky which he uses to ultimately create just one photo. Once he’s cleaned up some of the background noise, variations due to the atmosphere and issues created by the camera, he will compile the images into one photo and processes the massive file in a digital darkroom. He wants to bring out as much depth and detail as he can, he said.
“With amateur gear, we can easily put our images up against the Hubble (Space Telescope),” he said.
That’s because amateurs can spend hour upon hour chasing after one star, or set their camera to take a series of photos from the backyard all night. Taking a picture from the Hubble is a much more expensive proposition, he said.
“NASA’s is a rental. It’s very limited,” he said, “It’s very precious. And they’re not really concerned with the aesthetics.”
Knutson also spends hours tinkering with his setup, fixing problems and trying out new techniques. He said there are about as many different ways a person can take these photos as there are stars to photograph. They range from very cheap and clever gear to very expensive and luxurious set-ups.
On the cheap end, photographers sometimes mount their cameras to what’s called a “barn door tracker,” which isn’t much more than a couple of planks of wood and a long screw. The photographer gauges the movement of a star or other object by feel and tracks the object by slowly turning the screw. That may cost just a few hundred bucks, but it takes a lot of education and even more know-how to do properly.
On the other end of the spectrum, there are the people who use a site called New Mexico Skies. That’s a plot of land filled with private observatories atop a dark hill near Cloudcroft. Amateur astronomers who can afford to use the site will set up automated equipment there worth hundreds of thousands of dollars.
With enough money, a person could sit in an overstuffed leather chair and take all the deep-space images he or she wants. That may be a good option for anyone who has enough money to spare that they have considered renting out a small country for a child’s birthday party.
With only about $1,000 in his system, Knutson is currently at the lower end of the hobbyist continuum, but his system is no barn door tracker either.
In the past, he has sunk quite a bit of cash into his hobby, though. He used to have a setup with a telescope and a tracking system, but he sold several key components and gave the money to a friend who needed help out of a bind.
After a few hours of trying to photograph an object off of Orion’s Belt, Knutson finally packs his equipment into the back of the Jeep and calls it a day.
It wasn’t a lack of ability, a lack of fancy equipment, the glow from Albuquerque or a neighbor’s light bulb that ruined all of Knutson’s photographs on April 16. It was a bright, clear moon that washed out all the pictures, he said.
Knutson is not discouraged, though. He’s preparing to move to Colorado, and said he’s already planning to purchase some better equipment — including more telescopes and a thermoelectrically cooled camera or two. He even wants to put together a dedicated observatory with a roll-off roof in his back yard in Colorado.
“You can go so deep into this,” he said. “Everyone has their own custom flare to it and their own approach. It’s an interesting animal.”
Knutson’s mother, Charlotte, said she’s not sure why her son ended up being so good at technical, complicated hobbies like astrophotography. Knutson, whose day job is leading a team of programmers for a telecommunications company, also builds race cars and video game cabinets.
“He’s so creative,” she said. “There’s nothing he can’t build. … He’s out there. I just shake my head all the time. (His father and I) are not brilliant like that. I’m not sure what we did.”