Absolute optical B-band magnitude B_mag vs. absolute radio brightness at 1.4 GHz P_{1.4 GHz}. Red diamonds are sources with spectroscopic redshift information from the SDSS. For the black squares, photometric redshifts were determined (see Sect. 6.2). The border between radio-loud and radio-quiet AGN defined by Kellermann et al. (1989) is plotted as a dashed line. The relation described in Gendre & Wall (2008) to separate FRI and FRII objects is shown as the dash-dotted line.