Observed Stokes profiles (dashed curves) in two pixels (left: pixel 1, right: pixel 2) located at the inner penumbra of the CEF region (see blue crosses on maps displayed in Fig. 3a). From top to bottom: Stokes I, Q, U and V. The vertical lines in Stokes I and V panels indicate the position of the λ⁻ (blue) and λ⁺ (red) used to calculate the magnetic field strength with three different methods (see the main text for a description of the methods): the solid lines in the Stokes V panels show the splitting derived from Method 1; the solid lines in the Stokes I panels correspond to the line splitting obtained with Method 2; and, the dashed lines in both I and V panels indicate the splitting derived from Method 3. The vertical dashed green line shows the wavelength position used to separate the two Fe I lines.