Quantum-efficiency curve of the QHY411M camera (window included). Top: three independent measurements at the same location are superimposed. The solid black line corresponds to a smooth B-spline fit to the data. Middle: residuals to the B-spline fit. The three colors correspond to the three independent measurements. Bottom: breakout of the noise in the quantum-efficiency measurement according to the origin of the contribution from the four different terms in Eq. (4). The plot also presents the quadratic sum of the four contributions (solid black line) and the RMS of the three independent measurements recalled from the middle panel (dotted black line).