LetTheRightLensIn said:
neuroanatomist said:
IMO, their Measurements (screen) are valid and quite useful. Their Scores are steaming pile of misleading cow excrement.
Just a little reality check...
(screen) isn't usually the best setting to compare sensor camera vs camera, it can tell you things that are useful, but using (print) to compare various sensors generally makes more sense and for a more fair comparison
I suppose it depends on your goal. The screen data are the real measurements, print is normalized. Normalization is fine if you understand what it's doing, but suboptimal if it introduces bias. In this case, while normalizing to a fixed 8 MP purportedly allows comparison across sensors, it also introduces bias - the greater the delta between the sensor MP and the arbitrary 8 MP, the greater the skew - that's part of the reason behind the chart-topping D800 scores. When analyzing data, one should always be on the lookout for spurious or 'impossible' results - a DR greater that the bit depth of the ADC is an example of that, seen in Print results (which are not quite measurements), but not Screen measurements.
Screen measurements are the raw data, and I always prefer to start with the raw data when doing an analysis. Black boxes are bad science.
Orangutan said:
neuroanatomist said:
which explains how a camera with 14 bits per pixel can, according to DxOMark, actually deliver a dynamic range greater than 14 bits of EV.
Question for you: my understanding of Bayer pattern sensors is that a group of 4 monochrome {R|G|B} are de-mosaiced to form one color RGB pixel. If I combine two 14-bit wells I get (roughly) one 15-bit well. If I combine four 14-bit wells I should get (roughly) one 16-bit well. Certainly they wouldn't do a crude addition of wells, but it seems very plausible that you can get >14EV DR, even without re-normalizing. What's wrong with this interpretation?
DxO is measuring the RAW image data, prior to demosaicing, so the ADC is the limit. That's why the Screen measurements are below 14 EV; only the normalized Print values exceed the electronic limit.
sarangiman said:
I'm just surprised at how many people call foul at DXO without taking the effort to really analyze what the measurements/results show.
I agree, I trust their measurements and in fact, use their software for RAW conversion. It's their normalized/massaged/weighted-averaged Scores that I don't trust. I know from direct experience (in my day job) that a set of raw measurements can be reduced using different, internally consistent and seemingly logical methods, to support diametrically opposed conclusions. I'm very glad that DxO post their raw data, I just don't agree with what they do with those raw data.
jthomson said:
Strange that they can get the Nikon D600 out on the day that it is released but haven't yet got around to the 1DX.
That speaks to an entirely different potential bias, but without knowledge about the rationale for the discrepancy, no conclusions can be drawn. Maybe Nikon overnight shipped them the first D600 off the line, and they're still waiting on a retail back ordered 1D X. Heck, noted bird photographer and Canon Explorer of Light, Art Morris, just recently got his 1D X - I've had mine longer than him.