Pianist finger movement contains information about note preparation, accent information as well as personal identifiers. However, no system for detailed finger tracking presently exists that can also be used ecologically: at an acoustic piano whilst also incurring acceptably low disruption to the performance. An optical motion capture system is described using a monocular camera setup to track passive UV paint markers placed directly onto pianists’ fingers. Tracking accuracy and 3D estimation algorithms are evaluated. This low-cost, efficient system maximizes its uses in performance analysis experiments which are most importantly not confined to laboratory environments.