Is DxO useful or even valid?

Started Oct 20, 2012 | Discussions thread
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Chris Noble
Chris Noble Senior Member • Posts: 2,344
Is DxO useful or even valid?

I have seen lots of comments on various threads that suggest that DxO's image quality formulas don't match what people see on the screen when comparing different cameras. See example below. Has anyone done side-by-side image comparisons to confirm that DxO's numbers are useful or even valid? By valid I mean that they actually measure differences that are perceptible, and that a "better" DxO score looks "better" on the screen rather than looking the same or (maybe?) worse. I have not found this anywhere on the DxO website, but if I missed the link I'd be pleased to be corrected.

Kim Letkeman wrote

Yes, and so what. Here is the tenet I follow ...

A difference that makes no difference, is no difference.

Trite, I will admit, but practically speaking the numbers are essentially meaningless.

While the differences may not be of much practical significance, the change from the G3 to the G5 (G3: ISO 667; G5: ISO 618) is in the wrong direction!  By contrast, the OM-D E-M5's low light ISO score is 826.  That's better than the Canon 650D (722).

I had me heart set on the O-MD for exactly this reason. It smokes the G5 at high ISO.

And then I processed a bunch of images from whatever sources I could fine, my favourite being ...

And I found that there was so little practical difference that I saw no reason to even consider this difference.


Granted, there are many factors other than sensor performance--or any single aspect of sensor performance--that go into the judgement of the overall quality of a camera, but, other things being equal, I'd like to see improvements in these measurable aspects.

So would I. All things being equal, which they rarely are. I am happy to see this GH2 derivative sensor doing very well and I am surely enjoying the excellent video. Something that would not be true had I bought the Olympus ... so all things are most definitely not equal in this case.

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