Patent ID: 8194314

Claim:
A pair of binoculars comprising: a pair of lens barrels each holding a telescopic optical system including a focusing lens; a diopter adjusting mechanism that adjusts diopter difference of one of the telescopic optical systems with respect to the other of the telescopic optical systems by moving the focusing lens of the one of the telescopic optical systems along an optical axis of the one of the telescopic optical systems; a diopter adjustment wheel that is not movable along the optical axis with respect to a body of the binoculars and includes an operation portion main body having a cylindrical shape and an operating knob provided on one end of the main body, and that moves the focusing lens of the one of the telescopic optical systems along the optical axis by a rotational operation of said operating knob about a rotational axis of the operating knob; and a diopter-adjustment-operation-preventing member that is provided on the same axis as the rotational axis of and radially outside the diopter adjustment wheel and adapted to move along the rotational axis to uncover or cover at least a portion of the operating knob and to make the diopter adjustment wheel either operable or inoperable.