With a DxOMark lens rating of 45 points, and a 29P-Mpix Sharpness score, the Zeiss Otus achieved the best results the labs have ever seen. At full aperture the Zeiss has excellent uniformity from corner to corner, horizontally and vertically, having less than 5% variation in sharpness across the image field regardless of aperture. Even at f16 where the effects of diffraction may be seen it has exceptionally high acutance (68%) and is less than 1% variation across the image field. Lateral chromatic aberration is very low and distortion is negligible. There is no vignetting by f4 but even at full aperture the -1.6Ev measured in the extreme corners is low on a fast standard lens like this.