A quick-acquisition optical sight for short-distance aiming or viewing enhanced with an illuminated reticle, e.g., a red dot, and intended for installation on a conventional long-distance viewing apparatus, the combination thereof comprising an integral assembly consisting of a mounting part attachable directly to the tubular scope without any intermediate adapters and a housing with an optical system that is pivotally supported by the mounting part. In spite of the fact that the quick-acquisition sight is approximately 30% smaller and less heavy than the smallest existing sight of this type, it incorporates click-type mechanisms for adjusting the position of the sight optical axis relative to the optical axis of the scope.