The first two rows show, from left to right, the photometric versus the Ca T spectroscopic metallicities (upper panels), as well as the residuals of the comparison (lower panels), on the CG97 metallicity scale and on the isoscale for Carina, Fornax, and Leo II. The last row shows the same for Sculptor. The error-weighted contours range from 0.5 to 2.5σ in steps of 0.5. The upper panel dashed line indicates unity.