This paper presents a fast , accurate and reliable modified Horn & Schunck approach for robust boundary preserving estimation of optical flow where only 30 iterations are used . The proposed method is derived from the benchmark algorithm of Horn & Schunck and Simoncelli's matched-pair 5 tap filters, such that it produces robust, fast and exact detection of motion boundaries and it is very simple to implement. Experimental results using synthetic and real optical flows are presented to demonstrate the effectiveness of our method in comparison to selected methods .