Sure 0eyvind, and thanks for the comments.
This shot was taken with my sigma 10-20mm set at 10mm. I set the camera to manual and dialled in a 25sec exposure at f3.5 and set the ISO to 800. Then I set up my intervalometer so the camera would take 145 shots one after the other. After the last frame was exposed I took two more additional frames. The first was so I could paint the tree with light. The second was with the lens cap on to act as a dark frame.
Once acquired I then batch converted the RAW files in PS and used a free piece of software (found here
) to automatically combine all the frames. Once combined I tweaked levels and curves in PS and finally used the gradient mask in IRIS (found here
) to remove some light pollution.
And that's it.