Effect of the flux unbalance on the results of MV1 applied to the Lundquist’s FR without expansion (ζ = 0). The results are shown for two cases of flux unbalance between the FR front and rear. The front limit is located where B_z, FR = 0 (ρ_front = 1) and the rear limit is set at a fraction ρ_rear of the FR radius. For comparison the case ρ_rear = 1 is shown in Fig. 3b. Left column: θ_x, θ_y, θ_z are the angles in degrees between the x, y, z directions, respectively, of the FR and MV frames. Middle left column: Δi and Δλ quantify the difference of axis orientations between the FR and the one found by MV, so the orientation biases. Middle right column: ratios of the eigenvalues eν_min, eν_int and eν_max. Right column: ratio of the maximum values of B_z, MV to B_z, FR (amplified by a factor of 100 for the first ratio). The horizontal dotted lines and the yellow regions are landmarks.