Abstract:
A focusing mechanism for an optical instrument includes an eyepiece having at least one lens element retained within an eyepiece housing, a stationary carrier for retaining the eyepiece, and a rotatable thumb wheel. A pair of levers operatively connect the eyepiece housing with the rotatable thumb wheel, the thumb wheel including corresponding pairs of cam channels on either side for receiving one end of a corresponding lever, the remaining end of each lever engaging the eyepiece housing, wherein rotational movement of the thumb wheel produces axial movement of the eyepiece relative to said carrier.