Okay, this was the only night during this northern lights activity period when I had a chance to try some great northern light pics.
The sky was almost clear, no wind, very good weather conditions. And no northern lights. This is the way it usually goes in Southern Finland.
Anyway, here are some tips for focusing in the dark using Olympus gear:
Turn Live View Boost on. If you want to use AF, the use Starry Sky AF. If you want to focus manually, use PreMF focused to 999,9 meters or use magnifying view. That is pretty much it, works fine.
Gear: E-M1 Mark III with Panasonic Leica 12/1.4.