Abstract: A range compensator for a gun sight for an associated gun is provided. The compensator includes at least one Risley prism pair that is rotatable in opposite relative directions about a common axis; mounting means for mounting the Risley prism pair to the sight between the sight and a target at a distance; and, a respective rotator associated with the Risley prism pair for rotating each prism in the Risley prism pair about the axis that is generally aligned with the path. The prisms are rotatable between an unrefracted range finding position in which a “line of departure” required to ensure the projectile strikes the target is determined and a refracted firing position in which the path of light extending between the sight and the target is refractively deviated to maintain the target centered with the sight when the gun is positioned along the required “line of departure”.

Abstract: A digital video telescope to support a person with vision impairment, due to adjacent target objects being too small, too distant, or too poorly contrasted to be adequately perceived. The user of the telescope provides real-time image processing with a variable zoom control to locate and magnify the target object and use a contrast enhancement feature to clarify and therefore identify the object. The telescope has additional features that facilitate the real-time processing of object images in adverse viewing situations, such as low light conditions and high levels of background light conditions. The telescope allows the user to dynamically tune out distracting information present in the image and concentrate on desirable feature of the object represented by the image, so as to facilitate object perception and recognition.