Upper panel: comparison between the log g from spectroscopy and that derived from Hipparcos parallaxes as a function of T_eff. The different lines represent linear fits in three different T_eff bins. The stars with error in parallax higher than 5% (not considered for the fit) are represented by grey triangles. Lower panel: HR diagram with our spectroscopic log g, our corrected log g values, and the log g using the Hipparcos parallaxes.