Abstract: A pair of variable-powered binoculars include a pair of objective lens systems; a pair of prism systems, each of the prism system inverting an image that advances through the corresponding objective lens systems, from an inverted image to an erecting image; a pair of concave adjusting lenses, each of the concave adjusting lenses placed between a focus formed by the corresponding objective lens system and the corresponding prism system, so that each of the concave adjusting lenses is movable along the optical axis formed by the corresponding objective lens system and the corresponding prism system; and a pair of ocular lens systems, each of the ocular lens systems placed on the optical axis, so that each ocular lens system is movable along the optical axis closer to or away from the corresponding concave adjusting lens, synchronizing with a movement of the corresponding concave adjusting lens.

Abstract: The invention aims at providing a pair of binoculars making it possible to easily perform a focusing operation and a diopter adjustment, and efficiently perform an assembling operation. The present invention provides a pair of binoculars having a pair of supporters for supporting adjustment lenses provided between a pair of ocular optical systems and a pair of objective optical systems so as to be capable of moving forward and backward along the optical axis, a focusing gear for performing a focusing operation by moving said pair of supporters forward or backward at the same time in the direction of optical axis, a diopter adjuster for performing a diopter adjustment by moving one supporter forward or backward in the direction of optical axis as keeping the other supporter stationary, and a focusing and diopter adjusting unit having a changeover gear for changing over the focusing gear and the diopter adjuster to each other.