Ellipticity measurement errors determined from MPFIT as a function of r-band magnitude. The measurement error for each case is the average of the e ₁ and e ₂ measurement errors. Across all magnitude ranges, especially for faint sources, combining two filters in the shape measurement decreases the measurement error. We obtained ∼20% more sources through simultaneous fitting given the same error cut (dotted line; δ e = 0.3).