In this paper, the optical conditions for the optimum combination of a rotating mirror camera with shadowgraphic devices or a interferometer are described, and equations showing the relation among the optical data in the optimum condition of the combination are given. When the camera is used together with the shadowgraphic devices, another equation in the paper shows that the product of the three main parameters (maximum frame size, diffraction resolution, resolution and sensitivity) is always a constant, and that -fche optical system should be designed to make the three parameters optimally match, finally, the optical structure suitable for the camera that is used to be combined with the shadowgraphic devices or the interferometer is a]so discussed hero.