摘要 |
A reticle adapter (100) for judging distance from an object (12) is used with a viewing apparatus (A) to detect relative positions of signals from at least two spaced apart marker devices (10) formed on a first object (12). An image of the relative positions of the markers is created within a field of view (16). A reticle projecting member (110) is removably mounted on the viewer (A). The reticle projector (110) forms a reticle signal (112) superimposed on the field of view at the scene input end (118) of the viewer (A). The reticle is selected to form a control area within which simultaneous appearance of at least two images of the spaced apart markers indicates that the first object (12) is at a distance at least as great as a desired distance from the viewer.
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