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In a 4 hour exposure, a rider passing through the frame in less than 1 second will not show up. The flash at the start is super fast - probably something like 1/2000sec or faster I’m guessing (don’t quote me on that being exact haha) So the rider and the trees in the Gunderson shot are light only for that split second, which is bright enough to freeze them into the frame.
Then the landscape needs to be dark enough that the trees will not be overly illuminated by the ambient light.
So to have a crack at recreating this shot you would need to be far away from any light spill from buildings, cats grooming runs, bright full moons, etc. My attempts have had ghosting because a) my flashes were not bright enough compared to the ambient and b) the ambient on the ground was too bright for the darkness of the sky (due to shooting close to the village at Hotham).
I’m thinking out loud though….