A matte box assembly is arranged for use with a camera rig including a camera body supported on a pair of parallel and spaced apart mounting rails extending in a longitudinal direction. The matte box assembly includes a matte frame surrounding a lens opening for alignment with the camera lens and a filter mount to support a lens filter spanning the lens opening. A support frame is arranged to be mounted on the mounting rails of the camera rig onto which the matter frame is supported for pivotal movement about a vertical axis between an in-use position aligned with the camera lens and an out-of-use position offset to one side of the camera lens.