Stereo vision systems have been proposed and used in various fields. They require cameras to synchronize with each other for tracking objects. In this paper, we present a vision system, which uses two normal, unsynchronized cameras for calculating the 3D position of objects. The unsynchronization in shutter timing of cameras is used to process more images per second than a synchronized camera system. 3D positions of an object are measured as a crossing point of lines in 3D through the detected position on the latest frame and estimated 3D position calculated by fast frames. This makes it possible for our system to consist of two unsynchronized cameras and allows for a PC to calculate the 3D position of the moving object at 60 fps. This can be useful for controlling a robot as a fast visual feedback system.