I must say that all of this “my camera is better than your camera” talk gives me a headache, and I’m not sure I want to get in the middle of this, um, whatever contest. I have read in detail the DxO results, along with many other test results and feel this debate is “full of sound and fury signifying nothing!” Bottom line to me is whether or not the camera in question is the best match for my needs. If you’re priorities are different, you should select a camera accordingly. DxO has performed a series of tests showing the D800 to have a wider dynamic range than other cameras, provided that you are at iso 800 or below. Also their results show the 5D Mark III to have maybe 0.5 stops more headroom on the highlights than the D800, but the D800 has well over a stop more headroom in the shadows. I love the slightly greater headroom in the highlights, as I shoot white wedding dresses and want to ensure I retain detail at that end. I also see in their charts that the S/N of the 5D Mark III is better than the D800, which is important for low-light photography to me, but clearly the D800 has more resolution. C’t Digital Photography (Fall Issue, 9, 2012) just did a very quantitative review of the D800, Canon 5D Mark III, Olympus OM-D, Nikon D4, and Pentax K-01, and their results are similar to DxO, but add other interesting comparisons. The D800 wins for resolution & dynamic range at lower iso, but the Canon 5D Mark III has superior S/N (low noise). I shoot weddings, which often involve low-light shooting, so for my needs, the 5D is superior. Would I like greater dynamic range? Sure, but not at the expense of S/N. DxO results, in their raw form, just provide another piece of useful information to help camera buyers evaluate equipment against their needs. Looking at their scoring system, it’s clear to me that they consider resolution and dynamic range to be most important, and therefore, rate these two parameters much higher than others to achieve their ratings. Yes, I find it amusing that they quote dynamic range in their final model for the D800 (14.4 Evs) wider than the 14-bit converter, which tells me that their models are not quite 100% accurate. I also find this true in that they rate the Canon 5D Mark III and the Canon 7D as both 11.7 Evs, whereas, when I shoot a Sekonic target using both cameras & the same lens/lighting conditions, camera settings, I get about 1.5 stops more dynamic range with the 5D over my 7D, gaining both in the highlights and shadows over the 7D, using Sekonic’s light meter calibration software. So I see DxO testing results to be useful, but not the absolute determinate of overall camera performance.
In the end, I don’t see either camera as absolutely the best in all ways, as they each have their strengths and weaknesses. For me, the Canon 5D Mark III is a wonderful tool, meeting my present needs beautify, and I wouldn’t trade it for the D800 at this time, as the pros do not outweigh the cons for me. As for others, their needs, interests, concerns might be completely different—LOL, some are obviously drastically different, reading the comments on this blog, but that’s perfectly ok with me, and I hope you’ll share some of your beautiful work, but I will smile if I find the photo acclaimed to be the best was taken with a cell phone! ;-)