We are fortunate, living at 58 degrees north, that from time to time we get to experience the aurora borealis, the northern lights, merrie dancers or whatever other name you care to use. In October 2015, we had a lovely display, and last night, another strong and stirring performance from the dancers.
It is not always easy to photograph the Northern Lights. I set my faithful old Nikon to manual focus, and select an ISO sensitivity of 400. Usually both settings are on automatic. I usually prefer an aperture of around f8 or f9, to overcome any possible optical defects of the lens and to manage depth of field, but for this purpose it is better to open the aperture, and I leave it at full aperture for the aurora. For exposure, I keep my usual aperture-priority setting, so the camera decides for how long to keeo the shutter open during exposure. The aperture setting and ISO selection is to try to get as much light as possible to the sensor, and so that the exposure does not need to be too long. Of course a tripod is essential. There must be ways of improving these settings, and I suspect I should experiment with dialling in some exposure compensation to increase the light to the sensor.
As usual, I do not like manipulating the image after it comes from the camera. Occasionally I may increase the saturation or decrease the gamma, but other than that most of my pictures are straight from the camera. Some dreadfully artificial examples are published of severely "photoshopped" aurora images, and while very artistic, I am sure, the implication that nature needs a creative boost in this case seems unnecessary. I'm definitely not saying I have my images as I would want them, or making claims that these are good pictures, and I would love to learn different and better techniques, but just stating personal preference about how I get the pictures.