Many bow sight designs and configurations are known. Bow sights often have multiple sight points that are used when shooting arrows at targets positioned at different distances from the archer. Many bow sights include multiple sight points attached to horizontal pins; examples of such bow sights are shown, for example, in U.S. Pat. Nos. 5,103,568; 5,676,122; and 5,685,081. A more recent development has been a bow sight with vertical pins having fiber optic sight points at the ends of the pins; an example of such a bow sight is shown in U.S. Pat. No. 6,418,633. A number of U.S. patents disclose bow sights having various other arrangements of sight points. See, for example, U.S. Pat. Nos. 3,234,651; 4,120,096; 5,086,567; and 5,131,153.
Until recently, bow sights have been designed to provide accurate sighting over changing distances only where the elevation difference between the target and the shooter remains relatively constant. Generally, each sight point is designed to be calibrated at a different distance measured from the shooter while the vertical displacement, or elevation, between the shooter and the target is assumed to be constant. As such, if a bow having sight points adjusted to be accurate over level ground is used to shoot at a target located either above or below the shooter, the resulting shot will be off target. More specifically, if the target is below the shooter, the sight will overcompensate for the arrow drop due to gravity and the shot will be too high.
To ensure accuracy, traditional sight points require manual readjustment whenever the relative elevation difference between the shooter and the target is varied. New bow sites have been developed that automatically readjust to maintain accuracy when the bow is used to shoot targets located at different elevations relative to the shooter. See, for example, U.S. Pat. Nos. 6,145,208; 5,253,423; and 5,121,547. Nonetheless, the current sights in this field can be improved with respect to their accuracy, ease of use, reliability, and simplicity.