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Scientist develops tool to photograph solar eclipses with smartphones

While many are picking up solar eclipse glasses for their eyes, an "eclipse fanatic" reminds viewers to protect their cellphones.
Scientist develops tool to photograph solar eclipses with smartphones
Posted at 1:39 PM, Mar 18, 2024

Douglas Duncan is a self-proclaimed "eclipse fanatic." The emeritus faculty member in the Department of Astrophysical and Planetary Sciences at the University of Colorado Boulder has chased eclipses worldwide since 1970. 

Duncan has viewed 11 total solar eclipses. He plans to make the total solar eclipse on April 8, 2024, his 12th, weather pending. 

A nearly 100-mile swath of the U.S., from Texas to New York, will be in the path of the total solar eclipse. Most of the rest of the U.S. will be able to view a partial solar eclipse. 

Duncan said those within driving distance of the total eclipse should make the trek to be in in the path of totality. 

"A 90% eclipse is like listening to music on cheap earbuds," he said. "A 100% eclipse is front row at the live concert, which can blow you away."

During a total eclipse, Duncan said it is easy to lose track of time as the experience only lasts a few minutes. He said he only planned on taking six photos when he first wanted to photograph a solar eclipse. He ended up taking 21. 

"I realized, oh my God, I haven't even looked at it," he said. "So I looked at it. I looked with the binoculars for about 20 seconds. I took a picture of the diamond ring at the end.

"When it was done, I looked at my camera, and I had taken 21 exposures, and I was planning on taking six. So I had completely lost track of time, and it went really fast. There's never enough time."

With the advent of cellphone cameras, he discovered that many eclipse viewers have the same issue. They're trying to quickly capture a rare moment that will, at most, last a few minutes. 

With the inspiration from his 29-year-old daughter, Duncan developed a tool to help people safely photograph solar eclipses. 

"If it's not in your phone, it didn't happen like that," he said. "Of course, people want a souvenir and I noticed people trying to hold up their eclipse glasses and their phone and trying to take a picture."

SEE MORE: What kind of solar eclipse glasses do I need?

What is Solar Snap?

 Duncan helped create Solar Snap, a filter that fits over a cellphone camera and helps protect lenses from being damaged by the sun. It is also paired with a smartphone app, which when combined with the filter, allows users to easily capture the solar eclipse as it gets close to totality. 

"Honestly, it wasn't rocket science," he said. "I'm surprised that nobody did this before, but your phone needs protection just like your eyes, and now it's very easy to get it."

Duncan said that the filter should remain over the lens of a camera until a few minutes before totality. The reason is due to the brightness of the sun. 

Even when the moon blocks 95% of the sun, the sun still has the brightness of 20,000 full moons, he said. 

How to take the perfect eclipse photo

The Solar Snap app helps users set the exposure, zoom and focus during an eclipse. He recommends that when the partial solar eclipse begins, users keep the same settings on the app throughout the duration of the eclipse. 

For those in the path of totality, he suggests removing the filter within a few minutes before totality. Once totality begins, the total eclipse is best viewed without filters. 

"The intelligence built into your phone is really good about making exposures for faces and people and scenery, not so hot for a round whitish yellow thing on a blue sky," he said.  "So I worked with a real nice savvy phone programmer and we just tweaked our own software until it was really, really good for the sun."

With advances in cellphone technology, some of the photos could capture some neat details. One effect is known as Baily's beads. 

"It is actually the light sneaking through valleys on the edge of the moon," he said while demonstrating a photo. "You know, if you think about it, the edge of the moon is not perfectly smooth. It's got mountains, got valleys and wherever the light sneaks through, you see these little pinkish bright lights, and it's very, very cool and you see that with your eyes. So, this is actually all done with an iPhone 14, and pretty nice pictures."

Don't spend too much time taking eclipse photos

Although Duncan is the creator of a product designed for solar eclipse photography, he actively encourages those in the eclipse's path not to spend too much time taking photos. 

"So watch for a while, and then, OK, I'm gonna take a couple of pictures, and then I'm gonna watch some more," he said.

Duncan will be among 600 viewers headed to central Texas to take in the April 8 eclipse. 

"A whole lot of people have said to me on my trip, 'I'm just gonna bring a pillow, I'm gonna lie down on the ground and then it'll be easier to see,'" he said. "These little practical, logical things, they're actually really important."

Other tips for viewing the eclipse

While Duncan said you'll still need regular solar eclipse glasses for your eyes to view most of the solar eclipse, those glasses should come off for the duration of the total eclipse. 

He says the moment of a total solar eclipse is unforgettable. 

"The hair on the back of my neck extends up," he said. "It gets cold, gets really cold. And then the people around me do all kinds of strange things. Some start to cry; some start to applaud; some start to cheer, but everybody does something. So it's quite a profound experience, and you have a challenge. All my career is to describe the indescribable as best you can."

Duncan also says viewers can use a set of binoculars while there is a total eclipse. Binoculars should only be used during the brief moments of totality, but they can provide an up-close look at the sun's outer gases. 

"The view of the corona in binoculars during totality, I've never seen anything more beautiful or ethereal," he said. "It's really, really important right to only use the unfiltered binoculars during totality."

He also suggests viewers bring plenty of sunscreen and a hat, as even a partially blocked sun can cause sunburns during the middle of the day.

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