Northern Lights are the result of the collision of electrically charged particles from the sun as they strike molecules in the Earth's atmosphere.  When all of these particles collide, they light up.  The different colours of light are result of the different gases in the atmosphere.  When oxygen is excited it gives off the green light and nitrogen will give off the reds, purples and blues.  

Generally, scientists and astronomers can predict when the Northern Lights are likely to occur.  They know when a mass of these electrically charged particles erupt from a sunspot on the surface of the Sun... this is called a Coronal Mass Ejection (CME) and it causes a Solar Wind.  For us to see the Northern Lights, the CME has to be directed towards earth.  It generally takes around 40 hours for the wind to travel the 150 million kilometers to Earth!   When the solar flare is very strong, we can often see the magically dancing curtains of light... when the flare is weaker we tend to only see bands of colour on the horizon.

A few days ago, the sun had a very large Coronal Mass Ejection (CME) that spewed these electrically charged particles towards earth.... scientists predicted that we would be able to see a very strong display of Northern Lights.... possibly as far south as the Oregon.  However, as with all weather... sometimes the predictions are wrong.  This time the magnetic field from the solar wind did not line up properly with the magnetic field of the Earth.

The best tools we have that predict Northern Lights are the following websites.  You can sign up for "Aurora Alerts" on two of the websites... they will email you a Yellow Alert when the Northern Lights are likely to occur in a few hours and then they will email you a Red Alert when the Northern Lights are actually visible.

• www.aurorawatch.ca    is a website from Edmonton and is one that you can use to sign up for alerts.
• www.auroraforecast.gi.alaska.edu  also sends out alerts and shows maps with the forecasted activity and the current activity
• www.spaceweather.com  has all sorts of information about all different kinds of space activity.  They show the current Auroral Oval from NOAA/POES  and when you see Red over the portion of the map that is Calgary... its time to go look outside!  They also show the Planetary K Index.  As the number in the K Index increases, the edge of the visible Aurora has moved further South.  For us to see it in Calgary, we need to have a Kp=4 and we will see the Northern Lights low on the horizon.  Kp=5 will be a display overhead and Kp=9 is a full blown storm which will display the Northern Lights as far south as the mid to southern States!

So that is a brief explanation of the Northern Lights.... now how do we photograph them and what equipment do we need?

• Sturdy Tripod
• A Fast, Wide Angle Lens with an aperture of at least f2.8
• Cable Release or Remote Release will come in handy
• Flashlight or headlamp

​I usually set up the camera at home where its nice and warm and I can see what I'm doing without the use of a flashlight.  I'll even mount the camera on the tripod before I leave the house.  Make sure you remove all filters from the front of your lens.  You then need to do the following

• ​Set your ISO.  Depending on your camera and how much noise you have at higher ISOs will depend on what ISO you set it to.  I generally set it to an ISO of 800 or higher.  With a point and shoot or a lower-grade camera you may have to set it to 200 -400 and then you will have to use longer exposure times. 
• Turn off your "High ISO Noise Reduction" and "Long Exposure Noise Reduction"   If you leave this on, you will have to wait between exposures for your camera to churn through its Noise Reduction procedures.  Plus on occasion, I have seen where the camera confuses stars with noise and it will try to blend the stars, which just results in a blurry mess.
• If possible, shoot in RAW
• Set your camera to Manual.  
• Set your Aperture wide, to as low an f-stop as your lens will allow.  (smallest number... hopefully f2.8 or lower)
• Set your Exposure Time to anywhere between 5 - 25 seconds.  You will have to check your image on the LCD screen, if it is too dark increase the exposure time... if it is too bright decrease the exposure time.  I usually put the camera on BULB and use my Cable Release to start the shot... and then I just count to myself and stop the shot at 10 seconds, I look at the photo and then adjust my count accordingly.
• Turn off your Auto Focus.  If you leave the autofocus on during a long exposure, the lens may hunt for focus resulting in a blurry photo.
• Focus on Infinity.  Its best to experiment with this during the day so that you can see where your lens gives you the best focus.  I'm lucky to have a lens that is sharp when I set the focus using the 'infinity symbol'.
• Compose your image and click away!

Remember that the Northern Lights may be extremely faint to the naked eye, but they will look great in a photo.  The camera's sensor has a much higher dynamic range for colour at night than the human eye does.  So if you're not sure if those are Northern Lights or not... take a photo and look at your Screen.

Now sign up for those Aurora Alerts and get out there and have fun shooting the Northern Lights!