Fraction of valid pixels in each spectrum across the CALIFA FoV (left panels) and as a function of wavelength (right panel) for the V500 and V1200 setup. The spaxels most severely affected by the vignetting in the blue and red part of the spectra lead to the ring like structure around the FoV center. The blue part of the V1200 data does not show a vignetting effect here because we cut off the wavelength range in the final data already at 3650 Å due to the very low sensitivity in the blue. Four bad CCD columns are visible that lead to a significantly reduced fraction of valid pixels at narrow wavelength regions.