Photographing the Northern Lights is not easy, the trick is to experiment and establish what works and then take enough images to ensure you have enough variety.

The trick is to ensure you get no movement during a relatively long exposure.  To achieve this the camera must be solidly mounted on your tripod. Use mirror lock to reduce vibration and either a cable release or two seconds delay (or both).

The actual settings was a trade off of many thoughts.

* Manual mode to give the greatest flexability taking all other considerations in mind.

* High ISO to reduce exposure times but not to high to produce noise.
(800 ISO used)

* Lens relatively open to also decrease exposure times
(generally we used F4)

* Manual focus on infinity (generally using the infinity settings because it very hard to use anything else due to the low light)

* Short enough exposure times to stop star trailing showing
(we generally used between 15 and 40 seconds with about 25 being the average)

All the images look good when viewed at the time on the back of the camera during the dark night.
* Therefore it is vital to use the histogram on the camera to check exposure and keep making adjustments.