A focus presetting mechanism for a camera lens assembly including an annular member fitted on the outer diameter of the lens assembly and rotatable relative thereto about the optical axis thereof which may be clamped at a fixed angular position in order to establish a predetermined focusing point at which the focusing ring of the lens assembly may be stopped. Stop members operatively interposed between the annular member and the focusing ring enable the focusing ring to be repeatedly returned to a predetermined focused position when the annular member is maintained clamped at this position.