Patent ID: 7277224

Claim:
Binoculars which include a pair of observation optical systems each having an objective optical system, an erecting optical system and an eyepiece optical system, the binoculars comprising: a pair of displaceble optical elements, which are at least parts of the objective optical systems, respectively; a focusing mechanism that is used to move the pair of displaceable optical elements for focusing; a pair of guide shafts corresponding to the pair of displaceable optical elements, each guide shaft of the pair of guide shafts being arranged in parallel with a corresponding displaceable optical element, each guide shaft of the pair of guide shaft guiding the corresponding displaceable optical element when moved by actuation of the focusing mechanism, each guide shaft of the pair of guide shafts serving as a turning center of the corresponding displaceable optical element; a pair of engaging portions formed on a pair of frames that hold the pair of displaceable optical elements, respectively; and a pair of guide grooves provided with respect to the pair of displaceable optical elements, respectively, the pair of engaging portions being inserted in and slidably engaged with te pair of guide grooves, respectively, the pair of guide grooves having inclined portions that incline with respect to the optical axes of the pair of displaceable optical elements at at least parts thereof, respectively, wherein, when the pair of displaceable optical elements are moved for focusing with the pair of engaging portions being engaged with the inclined portions of the pair of guide grooves, respectively, a distance between the optical axes of the pair of displaceable optical elements changes, thereby a convergence value being compensated, and wherein the pair of engaging portions have a pair of projections formed on the pair of frames, respectively, said projections formed to have substantially spherical surfaces at portions which contact inner surfaces of the guide grooves, respectively.