Abstract: The invention relates to a one-hand control unit for controlling movements in optical instruments. The control unit corresponds in its configuration essentially to a computer mouse and has a mouse roller ball 2 on its lower side, an additional rotational transducer 3 at the thumb position and two or three keys (5, 6, 7) on the side of the mouse lying opposite to the rotational transducer 3. The keys (5, 6, 7) are for actuation by the middle finger, index finger and little finger, respectively. The mouse roller ball 2 and the rotational transducer 3 preferably function to drive continuously movable elements such as the illuminating field diaphragm 13, the aperture diaphragm 12, the motorized focus 20 or a motorized object stage 21. The keys (4, 5, 6, 7) are provided for driving discretely adjustable elements such as the objective-lens turret 14 or the incident-light reflector turret 15 or for switching over between coarse drive and fine drive for a motor-driven focus drive.