The camera is on a tripod and the shutter tripped with a cable release. Behind, I am holding two pieces of cardstock taped together in the middle: one green, the other blue. In the other hand I'm holding a small flashlight which is used to cast light and shadow into the scene. The shutter is open for 15 seconds allowing the cardstock and flashlight to be slowly moved creating the effect. This is a single exposure with limited post processing in Lightroom.
April 22Twistedbluegreenlightpadshadowtime lapse