How much Dynamic Range matter?

Started Sep 26, 2011 | Discussions thread
boggis the cat Veteran Member • Posts: 6,324
Thanks, interesting article

JeanPierre Koenig wrote:

By the way, you may want to note that LL includes MANY different opinions (as they post articles by DIFFERENT people). Also, there is a great thing called a "search" engine. Took me a minute to retrieve this article. Could have taken you 1 minute too :).

Rikke isn't that interested in learning anything, as for all people who are here purely to cause trouble and troll.

From near the opening:

Since then though I have become increasingly concerned, because their DxOMark metric provides people with a number, precise to within one decimal point, but which has become misunderstood by many.

Firstly, such a level of precision is essentially meaningless. Statisticians call it spurious precision, since it creates an impressions of accuracy that isn't at all relevant.

(Not to mention they don't give any uncertainties.)

Does a ranking of 62.3 really differ in any meaningful way from 63.8? No, not at all. In fact DxO points out that a measure smaller than 5 is hardly perceptible, representing just a 1/3rd stop difference.

More specifically, over time it has become clear to me that there is an even greater flaw to DxOMark, and that is that it does not correlate one of the most important metrics, resolution, with its other measurements.

"This scale is based on three underlying metrics, Color Depth, Dynamic Range and Low-Light ISO."

The above quote from the DxOMark web site indicates the nature of the problem. Sensor resolution is not one of the metrics included. This means that a 12MP camera that scores a couple of points higher than a 24MP camera will be judged by most people as being superior by its DxOMark rating, even though, as we now know, less then 5 points difference is not even visible. Yet, camera one has twice the pixel count (1.4X the resolution) of the other. This flies in the face of both experience and common sense.

It is also worth pointing out that some sensors are very much equivalent at base ISO and with reasonable lighting, but fall off at higher ISO and in poor lighting. DxO is only testing one end of the usage spectrum, and it is the non-daylight shooting end. (The FT sensors all perform relatively poorly below a certain light level, and so are far from their best performance in e.g. indoor available light.)

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