During essentially all of this indexing time, a shutter must block the light incident to the film to prevent the appearance of “travel ghost” (smear of the image caused by film motion). The projectable frame time, which would appear to be approximately three-fourths of the total frame period, is further reduced to only approximately one-half of the total frame period because the typical motion picture projector employs a two-bladed shutter, which causes two blanking periods per frame of the film, in order to raise the apparent frame rate to 48 frames per second, and thereby greatly reduce the apparent flicker perceived by the human eye. Furthermore, it is necessary for these two shutter intervals to be nearly equal in duration in order to limit perceived flicker. Therefore, since one blanking period must be approximately one-fourth of the frame period in order to blank the projected image as the film moves, the other blanking period must be of essentially the same duration.