This invention discloses a riflescope wherein the point of aim is adjusted by a pair of partially-rotating wedge prisms. The prisms are positioned in front of the objective lens of the riflescope. The deviation axes of the prisms are oriented perpendicular to each other such that one deviates the light beam in the horizontal direction and the other in the vertical direction. It is shown, using the geometric properties of a tangent to a circle, that rotating each prism by a small amount can produce an approximately linear shift in the point of aim of the riflescope.
The riflescope introduced in this invention has no laterally-moving parts, no turrets and no off-axis optical components. Therefore, it provides a very robust and reliable point of aim. Additionally, the riflescope has a streamlined body which is aesthetically pleasing and easier to mount on the long receiver of magnum hunting rifles.