The Peterson R490 AutoStrobe Rackmount Tuner responds at the speed of light. The 8-octave tuner displays relative tuning of any audio source to 0.1 of a cent (1/1000 of a semitone) accuracy. With the AutoStrobe R490, students, technicians, and musicians at all levels can use automatic (hands-free) note selection for fast, accurate tuning of instruments. This feature also permits real-time display of intonation to improve performance and listening skills while playing. For in-line silent tuning during performance, it allows external input and through output with mute. It also features an automatic image clarity and contrast control for optimal viewing over a wide range of source pitch and volume.