The BF2 can measure three things:-Total incident PAR solar radiation, Diffuse PAR radiation and Sunshine status. It measures Sunshine indirectly, with reasonable accuracy, using a simple equation based on both the Total PAR radiation, and the ratio of Total to Direct PAR. It has a cosine-corrected PAR (Photosynthetically Active Radiation) spectral response. It is designed for use with the Sunscan Canopy Analysis System, or with a data logger.