Averaged scans of a spectral region of the solar Fe I lines and the telluric lines around 630.2 nm recorded with CRISP (dots) together with the scanned FTS spectrum of Neckel & Labs (1984), degraded by the transmission profile of CRISP, as determined from fits of the reflectivities and cavity errors shown in Fig. 2. The dashed curve corresponds to the transmission curve of the prefilter, as obtained from the same data.