Focusing apparatus is described for a lens holder for an actuator of a read/write head in a optical information storage system which provides a fine adjustment for focussing an optical beam on the storage medium. A lens holder unit is coupled to a base unit by springs, the springs establishing an equilibrium position relative to a base unit. The base unit includes a plurality of coils through which current can flow. The lens holder unit includes a permanent magnet. When current flows through the plurality of coils, a force is exerted on the permanent magnet and, consequently, on the lens holder unit. The position of the lens holder unit relative to the base unit is determined by the magnitude of the current applied to the coils. The springs are arranged to maintain an orientation of the lens assembly unit in space. For small displacements of the lens assembly unit from an equilibrium position, the lens remains proximate the optic axis. A second embodiment of the focus control element provides for a combination of tracking apparatus and focussing apparatus for positioning a focused radiation beam on a storage medium.