1. An auto depth-field capturing system for a camera comprising: a camera lens for taking plural images; a camera calibration device including an epipolar estimation module for estimating plural epipolar data of said plural images, and a camera extrinsic parameter estimation module for estimating a location data; at least a frame buffer for storing said plural images temporarily; an image rectification module for rectifying said plural images corresponding to said plural epipolar data and obtaining plural rectified images; a disparity estimation module connected with said camera calibration device and said image rectification module for receiving said location data and obtaining disparity vectors of said rectified images; a disparity to depth conversion module for obtaining a depth in response to said disparity vectors and said location data; and a depth image painting module for painting a 3D image in correspondence with said depth.