Focus adjusting device for binocular

摘要

A binocular belonging to one type is provided with a focus adjusting device which allows one to select a desired ocular lens feed rate. A single annular piece is included in the device to be rotated by a manually operated focus adjusting ring to in turn drive a shaft associated with ocular lens barrels in a reciprocal movement. A bunch of such exchangeable annular pieces are prepared each being formed with a helical slot which differs in pitch from helical slots in the others.