In article , Eric Stevens
wrote:

The problem is clearly DXO's testing methods. No matter how you look
at this, you have to be able to imagine all kinds of sources of
inaccurate measurements, especially if they are slight. I have to
agree with nospam and Alan. You can't get DR outside of the limits of
the ADC because that is the output you see, but you can certainly get
test results outside of that limit.

But the digital DR of the output of the ADC is not the same as the
analog DR of the sensor. Nor is there any reason why it should be.

nobody said it was, however, it's always going to be limited by the adc.

The recorded output of the ADC is limited by the capabilities of the
ADC. But these have no effect on the capabilities of the sensor.

again, nobody said the adc would alter the sensor's capability.

what you still fail to grasp is that whatever the sensor can produce
will always be limited by the adc, unless the sensor itself is the
limiting factor, which is not the case in a d800 class camera.

If
the sensor can discriminate between luminance levels from 'c' to 'q'
it will always retain that ability irrespective of the capabilities of
the ADC. How the ADC encodes it is another matter, and how that image
is decoded by RAW decoder is another matter again. There is enormous
scope for fiddling and adjustments.

except that no fiddling or adjustments are being done.

and if it really *is* the sensor they're measuring, then it should be
the *same* for the *same* sensor, and it is not.

Not when you shove another piece of glass in front of one of the
sensors.

no effect on dynamic range.

Nor when you realise that not all sensors will be identical
and all measurements are subject to errors.

especially when the methodology is itself an error.

if they're supposedly measuring the sensor's dynamic range, explain why
the nikon d50 & d70 differ by a half-stop, both of which used the same
popular 6mp sony sensor (as did pentax). other results also differ.

I have no way of knowing but the first thing I would suspect is the
circuitry between the sensor and the ADC.

then you'd be wrong. there is nothing between the sensor and adc, in
those two or any other camera under discussion.

the d50 & d70 are basically the same camera, with minor feature
differences, such as the d70 having two control wheels versus one,
compact flash versus sd card, slightly faster frame rate, wired remote
option, flash commander mode and some minor other things i don't
remember, none of which have *any* effect on the dynamic range.