Top panel: the theoretical response curves of the two TCI cameras, based on the properties of the dichroics, the quantum efficiencies of the cameras, and an assumed telescope transmission efficiency of 65%. Bottom panel: for comparison, the normalised response curves of the standard Johnson-Cousins UBVRI, and the measured sensitivity of the SDSS u′g′r′i′z′ cameras. Atmospheric effects are not included. This figure is adapted from Fig. 4 of Skottfelt et al. (2015b), with the permission of the author. The SDSS curves are based on a sensitivity determination made by J. Gunn in June 2001, available at http://www.sdss3.org/instruments/camera.php