The A_V vs. d plot for all the stars classified as dwarfs from the fields F1 (open circles) and F2 (filled circles) combined together towards L328. The dashed vertical line is drawn at 217 pc inferred from the procedure described in Sect. 2 (see Fig. 3). The dash-dotted curve represents the increase in the extinction towards the Galactic latitude of b =  −0.829° as a function of distance produced from the expressions given by Bahcall & Soneira (1980). The error bars are shown for only a few stars.