The northern lights in a spiral, from the display on February 1st, 2015. You can read about and see more photos from that night there if you like.
I bumped the aperture up a bit from the lowest f/2.8 to avoid vignetting at the corners. Vignetting tends to get bad on this lens when I have it fully open and at the shortest focal length. Still used only a half-second exposure because, man, the lights were bright that night!