An objective lens mount and a connection device are releasably connected. The connection device is part of an objective lens or an adapter. The objective lens mount has at least one abutment surface that cooperates with at least one counter abutment surface at the connection device. At least two V-shaped first positioning bodies with at least one positioning surface are arranged such that the positioning surfaces face the longitudinal axis. At least one counter positioning surface at the connection device abuts the positioning surfaces of the objective lens mount. The relative position in the circumferential direction is defined via a rotation stop of the objective lens mount that cooperates with a counter rotation stop of the connection device. A locking device retains the connection device at the objective lens mount and effects a force component in the axial direction and preferably a force component in circumferential direction.