skibum5 wrote:
Disagree here. You are not making good sense here. I mean come image they stored a CD as the values 65536 to 131071 instead of 0 to 65535? who cares (other than they\'d be wasting a lot of space in this case, although they would have to since you could then just declare that 0 bits set means 65536 and all 16bits set means 65535, who cares?)?
You\'ve misunderstood what I\'m getting at here. The issue is not one of how the sensor records the data. The problem with saying \"sensor A has 2 stops more DR than sensor B\" is that it doesn\'t really tell us whether that dynamic range is *useful*. That statement doesn\'t capture, for example, how the sensor might clip the highlights, or whether there\'s pattern noise that makes recovering information in the shadows useless. I\'m not saying it\'s entirely meaningless, but it\'s not something that can just be blurted out without qualification, either.
The overall ratings on DxO are close to junk, although not out and out junk. It\'s just hard to know exactly what to make of them. Their normalized individual numbers appear to generally be reasonably decent though. Their data seems to be same ballpark as what others get when they try to do similar measurements, for the ones that are easy for everyone else to do.
\"Appear to be,\" \"reasonable,\" \"hard to know exactly what to make of them,\" and \"seem to be [in] the same ballpark\" are not exactly quantitative statements, are they? Perhaps you need to read about Millikan\'s oil drop experiment to appreciate the significance of what I am saying, and the extreme care with which we must avoid fooling ourselves.
It\'s funny you just write off the entire site\'s numbers as junk and then talk about egregious lack of critical thinking skills.
I am NOT saying that DxO\'s measurements are wrong. That would imply I have arrived at a different set of results. I am saying that their entire methodology is suspect because what I *can* see is done so sloppily, and for the sake of a largely unquestioning audience, that one would be negligent to assume they only slipped up in that one respect. It\'s not necessarily junk data, but it absolutely is junk science.
Apr 23, 2011 at 07:47 PM
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