Comparison with the Hinode-based Fourier spectrum of the Doppler velocity by Rieutord et al. (2010). Solid black: spectrum from our second IMaX time series deconvolved with the PSF′ function introduced in Sect. 4. Dash-dotted: velocity spectrum computed from a power spectrum in Fig. 6 of Rieutord et al. (2010), for a time series obtained from Hinode/NFI for the Fe I 5576.09 Å line. Red and blue curves: velocity spectra from our 50 G MHD simulation run with spectral synthesis carried out for the Fe I 5250.2 Å line and for the Fe I 5576.09 Å line, respectively. To obtain those curves, we have not applied any instrumental degradation (PSF′ and MSRF) to the simulated data.