5dIII review at DxOMark

[Dr Croubie]

I'm also reading the graph of ISO, SNR 18%.
On Print, comparing photo to photo, the D800 and 5D3 are almost exactly equal, both above the 5D2.


On Screen, comparing pixel to pixel, 5D3 beats 5D2 beats D800.


How does the D800 score 2800 and 5D3 score 2200? Maybe only 1/3 - 1/2 stop, but I call shenanigans on DxO.

[Daniel Browning]

I'm also reading the graph of ISO, SNR 18%. On Print, comparing photo to photo, the D800 and 5D3 are almost exactly equal, both above the 5D2. How does the D800 score 2800 and 5D3 score 2200? Maybe only 1/3 - 1/2 stop, but I call shenanigans on DxO.

Good question. It's probably because the SNR 18% is calculated without consideration for chroma noise, while the Sports score is. For example, you can improve SNR 18% by making the green pixels accept more red light, and the red pixels accept more green light. But then when you apply a color matrix to get accurate colors back out, chroma noise goes up. That is precisely what Canon has done with some of their cameras.

Go to the individual data (not a comparison) for a camera and click on the "Measurements" tab and then "Color Response". You'll see that the 5D3 red pixels have almost the same amount of green as they do red. While D800 red pixels have a bigger difference between red and green. Same with blue. The 5D3 is almost a YGB (Yellow Green Blue) sensor instead of an RGB.