He was set up in his "secret spot" in Russell, overlooking Long Beach with Rawhiti in the distance about 2.30am last Sunday, photographing the Milky Way.
Haeni said during the camera's 30-second exposure, the lightning "flashed at the right time".
The result was stunning. The top part of the photo shows the Milky Way in all its splendour, while the lightning storm lights up the lower part of the photo.
He said it was "a lucky moment in my life in a happy place".
The lightning was part of an electrical storm which was later identified as the cause of mysterious flashing lights reported by Northlanders on social media last Saturday.