Inferred photospheric Fe abundances from detailed non-LTE calculations using the 3D hydrodynamical Stagger model (upper panel) and the 1D Holweger & Müller (1974) model (lower panel). The results for Fe I and Fe II lines are shown as blue circles and red triangles, respectively. The solid lines denote the least-square fits to the Fe I results. In 3D non-LTE, there is excellent excitation and ionisation balance for Fe, contrary to the 1D case; it is noted that the trend with excitation potential with the Holweger & Müller (1974) model is even steeper in LTE (see Table A.2).