Quote Originally Posted by Daniel Browning View Post
It's pretty simple. You measure three areas of performance (DxO's portrait, landscape, and sports scores) and then average them together. The D800 sensor did better in all three, so it had a higher combined score.



No. Say Johnny gets 65% in Chemistry, 65% in English, and 100% in Math. While Sally gets 70% in all three. Sally beat Johnny in two out of three subjects, but Johnny's GPA is still higher. Are you to infer that Math is the only subject that matters when calculating someone's GPA?

Any time you try to reduce something down to a single number, it will *not* reflect the full reality and complexity of the situation.

Summarizing something as complicated and nuanced as sensor performance into a single number is impossible. But a lot of people *want* a single number, because they don't have the time or inclination to learn all that stuff. So DxO provides the solution for everyone.

At one end of the spectrum (technically-minded folks), it provides the full charts and data so you can go in and see how it really does for yourself. Make up your own metrics that reflect what you do with the camera, and use their data for it.

Towards the other end of the spectrum, DxO has chosen three particular measurements, that while they may not match your shooting exactly, they do reflect the taste and perception of many photographers. You merely choose how important each of these three are to you and weight them yourself (for one, low light may be twice as important as dynamic range and color depth; for another photographer, the reverse).

Then at the very end of the spectrum you have folks for whom even three numbers is too much. They only have time or inclination to compare based on a single number. DxO doesn't know how important the three factors are for every person, so they just weight them equally. I think that's a good choice, even though it doesn't match the weighting that I would use for myself, personally.
I'm just never going to get it. I noticed that the Nex7 scored the same score as the 5dIII. The Nex7 dominated the 5dIII in dynamic range at 2 iso levels (a little over one stop Ev). In pretty much every other category at every iso, the 5dIII dominated the Nex7 (http://www.dxomark.com/index.php/Cam.../(brand2)/Sony). But b/c the Nex7 had a little over one stop better dynamic range at two isos, it tied the 5dIII? It makes sense to me to combine and average percentages in terms of school grades. We all know what these percentages indicate. Is it really appropriate to combine and average three different sensor measurements into one overall score? I'm sure that DxO has some sort of conversion to make all the measurements relative (or are they just relative to some optimum?), but why is a little over 1 stop dynamic range at two iso settings weighted so heavily, especially at low iso levels? At five higher iso levels, the 5dIII dominates the Nex7 by approximately one stop of dynamic range. How is it possible that these sensors score the same?!?! It makes my head want to explode; but fortunately, I'm never buying either of these cameras, so it really doesn't matter.