It is not every night Aurora Borealis dances the skies of Denmark.
Our beloved sun gifted us with a surprisingly big geomagnetic jolt Tuesday pushing the colorful northern lights farther south covering Europe down to France. The storm was rank as a class 4 “severe” and is among the strongest we have seen since the fall of 2013.
Our luck was that the sky was fairly clear of clouds, and the absence of the moon didn’t interfere with viewing of the Aurora.
Summing up the learning from this night.
The skies from the shifting light turned out to be a problem, getting the right focus was tough. Therefore, I went for manual focus, trying to use a faint star to manual focus on. I guess I would have preferred arriving in day light, being able to make the camera do its auto focus before the light went away.
Setting the camera in RAW was a given, I absolutely wanted the maximum control. The Aurora was not as strong as I could have hoped for, but we found happiness at 16mm @ ISO 1600, f/2.8, 30 sec. I guess there is no absolute here; you will have to judge from the metering, I personally found that wide metering at my Sony Alpha A99 worked out best…
Respectively I would not have gone with 30sec, but rather tried different intervals depending on the movement of the light. The reasons is that the movement mixes, and some of the clear definition gets lost. Dave Morrow wrote, “Keeping your exposure time between 5-25 seconds will work very well for shooting the northern lights. When the aurora is moving quickly, try 5-7 second exposures, when it’s not moving as quickly try 10-25 second exposures.”
Read more at Dave Morrows fantastic blog
The Golden Hour 
http://www.swpc.noaa.gov/communities/space-weather-enthusiasts