Both aircraft were involved in a movie operation with the helicopter (n250ca) carrying a camerman. The dhc-6 (n203e) carried parachutists. The purpose of the operation was to photograph the parachutists exiting the jump aircraft. The pilot of n250ca said he was in formation with n203e and was maneuvering into camera position when the rotor blades contacted the vertical stabilizer and rudder of n203e. The pilot of n203e was not in a position to have visual contact with the helicopter.