Comparison to the distance scale of the open cluster sample of Bossini et al. (2019): detailed comparison to the four distant (d >  2 kpc) clusters studied with high-resolution spectroscopy (Melotte 71, NGC 2420, NGC 6819, and NGC 6791). In each panel, we show only stars with P_memb = 1 according to Cantat-Gaudin et al. (2018a). The first panel in each row shows the distance-A_V plane (grey-dashed lines refer to the values determined by Bossini et al. 2019), while the second panel displays the colour-magnitude diagram (only parallax-corrected in cyan, StarHorse-corrected in red). The third panel shows the metallicity-coloured Kiel diagram for each cluster. The metallicities derived from high-resolution spectroscopy quoted by Bossini et al. (2019) for these clusters are [Fe/H] = −0.27 for Melotte 71, −0.05 for NGC 2420, 0.0 for NGC 6819, and +0.4 for NGC 6791. The fact that we see on average much more metal-rich stars in NGC 6791 is encouraging: there is at least some metallicity sensitivity in the photometric data used in this work.