Designers are often asked to optimize the modulation transfer function (MiT) of a particular lens at specific fields and spatial frequencies. Use of a merit function related to mean square spot size or wave aberration to achieve these goals frequently requires considerable designer intervention. We describe an algorithm whereby diffraction MTF is optimized directly. The algorithm is efficient enough (i. e. on the order of five times the run time for classical techniques) to be used as a practical design tool. To illustrate use of the algorithm a previously designed night vision objective lens is reoptimized with the goal of increasing the MTF at a particular spatial frequency thus increasing the modulation margin allowed for tolerancing. Significant improvements in MTF and depth of focus are achieved with minimal designer effort and reasonable computation times. 1 .© (1991) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.