  We extend the formula for partition functions of N=2 superconformal gauge
theories on S^3 obtained recently by Kapustin, Willett and Yaakov, to
incorporate matter fields with arbitrary R-charge assignments. We use the
result to check that the self-mirror property of N=4 SQED with two electron
hypermultiplets is preserved under a certain mass deformation which breaks the
supersymmetry to N=2.
