Analysis of information sources in references of the Wikipedia article "Contax" in English language version.
[Subjective Quality Factor] data indicates that, as a group, the Zeiss lenses we tested with the G1 deliver top-notch performance. Specifically, the 28mm Biogon and 45mm Planar provide excellent overall image quality, while the 90mm Sonnar is the benchmark of its class—the best-performing medium tele we have so far tested. All three optics had little measurable field curvature, and their low distortion level was also commendable.