Reddening-corrected two-color diagrams (left panels) and reddened CMDs (right panels) for NGC 1651 (upper panels), and the surrounding field stars (lower panels). Left panels: stars with photometry in the vby filters (black points); stars excluded from metallicity determination (open squares); stars used to calculate the mean metallicity of a cluster and field (color-coded points, where colors represent the derived metallicity value); lines of constant metallicity (dashed lines); additional selection criteria drawn after visual inspection of the plot (dotted line); obtained mean metallicities of cluster and field stars (black solid lines); the statistical and systematic errors of the mean metallicity of the cluster (darker and lighter shaded areas); the reddening vectors (black arrows). Right panels: Dartmouth and Padova best-fitting isochrones (gray and turquoise dashed lines, respectively) superimposed on the field CMD (bottom right panel) aimed at illustrating the position of the cluster against field stars.