Nevertheless, there does appear to be an interesting paradox in the DXO measurements that I sometimes notice when comparing the graphs.
Oscar mentioned that the Canon 5D was considered to be ahead of its time regarding tonal range and color rendition.
Just out of curiosity I compared the measurements, at the pixel level, for the 5D and the D800 on the DXOMark website. I was surprised to find that the 5D pixel, at almost 3x the size of the D800 pixel, has about equal performance with regard to SNR at 18%, Tonal Range and Color Sensitivity. This is a good indication of the technological progress that has been made since the introduction of the 5D, the fact that a pixel almost 1/3rd the size can have the same performance with regard to noise and color sensitivity.
However, here is where I see as a paradox. The D800 pixel has almost 2.5 stops greater Dynamic Range than the 5D pixel, yet has no greater tonal range. How come?
If the Tonal Range measurement describes the number of distinct tones the sensor can record over its entire dynamic range from the deepest shadows to the brightest highlights, then one might expect the D800 pixel to also have a greater tonal range than the 5D pixel, if it has a greater DR. Those 2.5 stops in the deepest shadows also have a tonal range, surely.
I can only conclude therefore that the 5D pixel must have a greater tonal range within the useable DR that the pixels from both cameras have in common, that is, the range from the deep or low midtones to the brightest highlights. The entire tonal range within those darkest 2.5 stops that the D800 can record, but the 5D cannot, must be at the expense of the tonal range above those lowest 2.5 stops.
That's how I see it, but I might be wrong. My understanding of such technical matters is quite limited.