How do you capture the display of Aurora Borealis, or the Northern Lights? That was the question Frank Audet, a photographer from Quebec City, Quebec, helped us understand during our November 2013 Free Photo Webinar.
Photographing the auroras is about as much about science as it is about photography. The light shows occur when highly charged electrons from solar winds interact with elements in the earth's atmosphere.
Why do you need to know this?
"As many of you know, if you want to take great pictures of birds, you first have to learn how the bird behaves. The same thing applies to Aorora Borealis or Northern Lights," Frank said during his presentation. "You just can't go out there on a starry night and hope to shoot Aurora. There's a learning curve."
The challenge is not to shoot the Auroras, it's to find them.
To help us deconstruct the mystery, Frank's presentation explains:
- What is an Aurora?
- When are they occurring?
- How do you photograph them?
View the webinar recording
Coronal Mass Injections are massive bursts of solar wind ejected from the sun and released into the solar system. Websites like www.spaceweather.com monitor solar activity and can send you alarms when CMEs occur.
The intensity of the solar storm when it comes to Earth is defined by a scale: the K-index (Kp). A larger number means a more important storm and better chances of having Auroras -- and better chances of having them at lower latitudes. This site tells you the Kp typically required for your region: http://www.swpc.noaa.gov/Aurora/.
The Earth’s magnetic field needs to allow the CME to enter the atmosphere. This is the Bz index, which can also be found at www.spaceweather.com. When you have a south pointing Bz, CME enters the atmosphere and Auroras have better chances of occurring. Bz in North, chances don’t look good.
Final factors include presence of clouds of course, and the presence of the moon. A big bright full moon lowers the chances considerably.
What if you have the perfect conditions and still don't see anything?
"This happens most of the time," says Frank. "Remember that a camera sensor at ISO 3200 with the shutter opened for 30-60 seconds gathers much more light and is much more sensitive than your eyes. Even if you don’t see Auroras, if the conditions are theoretically good, point your camera north, include a few foreground interesting elements, do a manual focus on infinity, and open the shutter for several seconds."