I directly compared the Otus to the flagship 50mm lens from Canon, the EF 50mm f/1.2L. I praised that lens in many ways, and I do think it has more to offer than some have given it credit for. […] But at the same know that in every measurable head to head comparison (other than autofocus!) it was no contest. The Otus simply destroys it. The Sigma 50mm f/1.4 ART series lens is somewhat better competition in terms of sharpness, and (to a lesser extent) contrast, but in overall image quality it falls short of Otus. The Sigma ART is a very nice lens, but, ironically, it isn’t nearly as “artful” as the Otus 55. The Otus has not only the biting sharpness and overall contrast but also adds a truly beautiful out of focus rendering that just seems to produce more “creaminess” than any of the lenses I stacked it up against.
Photography Blog posted their full review of what is thought to be the world’s sharpest lens, the Zeiss 85mm f/1.4 Otus lens. And they tested it on a Canon EOS 5Ds[/shoplkink].
The Zeiss Otus 85mm f/1.4 Planar T* is simply a superb prime lens for portrait photographers looking for the ultimate in image quality. You’d expect sharpness to be high across both the frame and aperture range from such a premium optic, and it doesn’t disappoint. In conjunction with the new Canon EOS 5Ds test camera shooting at 50 megapixel resolution, detail is exceptionally detailed and sharp. Shooting at the maximum f/1.4 aperture does reveal a minor reduction in sharpness compared to the rest of the aperture range, but the image is already pin-sharp by f/1.8. Read the review at PB.