This paper reviews the properties which inherently limit the image quality of a gimbal mounted optical imaging system. It further describes how image quality is degraded by external influences, particularly vibration, in the supporting vehicle. The primary emphasis is to quantify, through physical principals, and verify, through experimental demonstration, the degree of static balance required to minimize the detrimental effects of external vibration to an acceptable level. The effects of dynamic balancing will also be discussed. The principles developed for visible light optical systems carried by an Unmanned Air Vehicle (UAV) will be expanded, in a general way, to describe how these principles apply to infra red, ultra violet, and radar systems as well as variations to the requirements as a function of the vehicle on which they are mounted. This discussion will include manned aircraft, missiles, land vehicles and watercraft.