The Targa III Dynamic Runout instrument measures runout on high-speed spindles at speeds up to 300,000 RPM. The new instrument has a noncontact capacitive sensor and a digital display with multiple measurement modes. The dynamic runout mode (DRO) presents a continuously updating TIR measurement that does not require manual reset when the TIR decreases. This feature allows measurement of DRO across a range of spindle speeds. Results of this test indicate the optimal speed for production operation of the spindle.