Smoke plume from a burning incense stick. Setup was a black muslin cloth as a backdrop, flashes without modifiers at 1/2 power on either side about 18″ away and a third flash at 1/4 power pointed up at the smoke from below. Camera in manual exposure mode at f/18, 1/250 sec and ISO 100 with manual focus hand held. Lights in the room were on, and had no effect on exposure.