What's interesting about the DXO tests comparing the D3X with the P65+ is that
Ray,
for the case that you want to know what is interesting in that comparison:
not if the deepest shadows are at a brightness level equivalent to 18% gray
18% grey has the intensity 18%. This is about 2.5 stops from clipping, i.e. in the middle of the third stop of the DR. Do you know a DSLR, which captures the third stop of the DR as "the deepest shadow"?
The P65+ still retains a noise advantage over the D3X in the mid-tones and lower mid-tones
From what did you infer this?
1. The noise of the D3X is shown as
lower at mid-level (18%), except in print, i.e. if the P65+ image is downresed.
2. DXO indicates, that the best DR of the D3X (with ISO 75) is 0.5 EV greater than that of the P65+ (with ISO 44). This relates to the deepest shadows, where SNR=1 is.
In fact, the DXO results show that at an average scene reflectance of 18% gray, the P65+ has 4dB better SNR than the D3X. That's more than a whole stop better.
1. Again, this is the printed (downresed) version. Of course, the P65+ is better.
2.
This decibel has nothing to do with
stop. The noise of the D3X with ISO 100, measured on an 18% intensive patch is 1.1%, which corresponds to SNR=90. The
printed P65+ image would show SNR=226 or about 0.44% noise.
This noise level is totally irrelevant.
DXO's 18% SNR is an absolutely useless measurement, it is for those, who don't know its meaning.
The fact that the D3X can have as much as 2/3rds of a stop lower noise in the deepest shadows, which may often be clipped to black for esthetic reasons when processing the image, is probably of little concern to the user of an MFDB system in the studio, but could be of concern, for example, to a landscape photographer shooting a waterfall in a dense rainforest, who wants to retain some detail in the surrounding, dense undergrowth of the forest.
1. Again, the noise is not 2/3 of a stop lower or higher or whatever.
"Stop" is not the measurement of the noise.There is one sense to qualify noise with stop: compared two not equal cameras, with the same ISO, the exposure of one must be a certain amount higher/lower than that of the other to achieve the same level of noise. This is just what DXO's DR tab shows: the same noise, namely SNR=1, will be observable with the D3X on 2/3 EV darker patches than with the P65+.
Not the noise is 2/3 EV lower but the intensity can be 2/3 EV lower to get the same noise.2. If someone cuts off the deepest shadows by black point, then one does not have any reason to talk about dynamic range.
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To the others: the above should not be interpreted as any position for or against any camera in the comparison. I do not advocate any measurement accept my own ones (and I don't have any usable raw images from the P65+ and not enough from the D3X).