The present invention relates to an optical system for reproducing and/or recording on optical record carrier. The system includes light providing means for providing at least: 1) a main beam for reading information, and 2) a plurality of auxiliary beams for radial tracking; a first (A), a second (B) and a third (C) auxiliary beam. The optical record carrier has readable effects arranged in tracks (2, 12) in one or more spiral(s), the spiral(s) being separated by one or more guard band(s) (5, 15). The optical system performs radial tracking from the reflected light of 1) the first auxiliary beam (A), the first auxiliary beam being positioned in a first guard band, and 2) the second (B) and third auxiliary beam (C). The second auxiliary beam is positioned on a first track (I), and the third auxiliary beam (C) is positioned on a second track (II) and on opposite side of the first guard band (5, 15) relative to the second auxiliary beam (B). The optical system provides improved radial tracking on the above-mentioned carrier format.