Realization of diffraction limited multi-element optical system to yield the best image quality, calls for tight fabricational tolerance on vital optical parameters such as radius of curvature, wedge, optomechanical centering etc., and state of art technologies in terms of fabrication, assembly and characterization at element as well as at system level. It was seen that, though the vital parameters are measured to accuracies of +/- 5 micrometers, < 10 arc sec, < arc sec respectively at integrated level, the MTF, the nodal parameter for assuring the system performance used to degrade even up to 20 percent. A systematic analysis at coupling the optical parameters to performance indicates that there exists an optimized plane specific to a system which can be arrived at only through global optimization of axial separation, relative elemental planes and tilts etc. In this paper, the details of a novel method to arrive at the global optimization of optical systems experimented is presented. It was seen that through this, realization of MTF close to the diffraction limit could be achieved. The methodology has successfully been adopted for various lens assemblies of f/6 and f/4.5 working in visible, near infrared and short wave infrared regions and covering a field of 26.0 degrees. Besides optimizing the MTF, it helps in relative matching of image format of different lens assemblies.