Behavior of the polarization degree with seeing for 1ES 1959+650 in the R band when two fixed apertures are considered (red circles for an aperture equal to 3 arcsec and pink squares for an aperture of 2 arcsec). In the left panel data points correspond to the observed polarization, P_obs, while the right panel shows the polarization corrected by the contribution of the host galaxy, P_intrinsic. Horizontal lines following the same color-code indicate mean values of polarization and are plotted to guide the readers eye.