1. A dynamic imaging system, comprising: an assembly line, for an object to be placed thereon and for moving the object in a moving direction; a sensor set, for sensing a moving speed and the width of the object on the assembly line; a photography device, for capturing images of the object; and a controller, coupled to the sensor set and the photography device, for controlling the photography device to move and capture images of the object according to the moving speed and the width of the object.