Relative contributions of Ca ii H and Hϵ to the intensity transmitted through the Hinode broad-band Ca filter. Top panel: average Ca ii H spectra near the limb. The vertical dotted and dashed lines denote the wavelength ranges attributed to Ca ii H and Hϵ, respectively. Second panel from the top: average observed on-disc (thick black line) and FTS spectrum (red line), and 0.3-nm-wide prefilter curve (dashed line, scaled arbitrarily). Third panel from the top: observed spectra at different limb distances. Bottom panel: relative contributions of Ca ii H (black line) and Hϵ (red line) to a 0.3-nm-wide prefilter.