On Thu, 17 Jan 2019 10:34:05 -0500, nospam
wrote:

In article , Eric Stevens
wrote:

also, their 'tests' claim what is physically impossible, making them
untrustworthy and their scale is whatever they want it to be, with
newer cameras scoring higher and higher.

Suspicion and innuendo. That's not evidence.

the evidence is quite clear that they cannot be trusted *at* *all*.

The evidence appears to be that you can/will not produce any evidence
to support that statement.

false, there is extensive evidence that dxo is a sham, but as usual,
you refuse to acknowledge that and just want to argue, now having
resorted to ad hominem attacks, as usual.

their 'tests' claim what is physically not possible. that alone makes
them a scam

Example? - assuming of course that you are able to cite one.

of course i'm able. i do not make false claims. period.

--- Claim by nospam: ----

dxo measured 14.8 stops of dynamic range on the nikon d810 and d850,
which is *higher* than the theoretical maximum of 14 stops (14 bit a/d)
and in the real world, it won't actually get 14 stops.

that's not *my* claim.

it's basic sampling theory, something which you clearly do not
understand at all.

What is the frequency of the signal being sampled?

I challenged this comment which lead to an enormous thread which
fanned out in all directions. My contention was (and is) that the
number of bits that are used to code an image have nothing to do with
the dynamic range of the sensor. You can code it with as many bits as
you like with factors other than dynamic range determining the choice.
In particular there is no reason why a sensor should not have a
dynamic range wider than implied by the number of bits with which it's
output is encoded.

your contention is wrong, which you even admitted in the middle of the
thread.

I bet you can't cite the article where I did that.

At one stage Ron C suggested I should explain my views with diagrams.
With some reluctance I have been getting round to doing this.
Preparing the diagrams so as to be able to deal with nospams of tghis
world is no mean task. In the course of my background research I found
the following thread from dpreview dated Mar 25, 2012.
https://www.dpreview.com/forums/thread/3170233

If you read that you will see that the maximum number of bits with
which it is worthwhile coding an image is determined by (a) read noise
and (b) pixel well size. DR vs number of bits is touched upon but no
one has suggested that sensor DR is limited by bit number.

the second post in that thread clearly does, further proof that you
don't understand the topic.

You mean where fvdbergh wrote "The dynamic range of a sensor is
typically limited by the signal to noise ratio (SNR), not the bit
depth of the analogue to digital converter (ADC)."?

Please note fvdbergh lower down wrote "A single point on the PTC will
give you the required SNR value, and hence the DR".

http://www.forzasilicon.com/2011/06/...-image-sensor/
or http://tinyurl.com/y8ztqbhk will tell you that 'PTC' is 'Photon
Transfer Curve' and says of this " the sub-ranging technique, where
each segment’s conversion step size is scaled according to the photon
transfer curve (PTC) of a given pixel."

I have many times talked about scaling the sensor output to the ADC
and you have repeatedly told me I was wrong.

I think it it's safe to say you don't know as much of this subject as
you you think you do and you understand even less.

This hopefully is my last post on this subject.

I also came across http://www.onmyphd.com/?p=analog.digital.converter
which is a good summary of the basics of analog to digital convertors
(ADC). Under the heading "What is an analog-digital convertor" the
author has written:

"An Analog-Digital Converter (ADC) is a widely used electronic
component that converts an analog electric signal (usually a
voltage) into a digital representation. The ADCs are at the
front-end of any digital circuit that needs to process signals
coming from the exterior world.

..... ---- complex text snipped ----

Therefore, more bits leads to more precision in the digital
representation. Here we simplify the range to be between 0 and
Vref, although the range may be between any two values."

That last has always been my point. What is being encoded is a signal
between gthe upper and lower limits to the sensitivity of the sensor.
Their mathematical relationship (as in their ratio = dynamic range)
does not come into the question. it is only their difference which
matters.

still not getting it.

I'm not going to write any more about the original argument. nospam
can go and find another playmate. I may be tempted to come back in if
a sensible and rational discussion of a new aspect gets under way.
Other than tghat I've finished with this thread.

ad hominem, and it isn't just me who has been telling you that you're
wrong.

come back after you've learned about sampling theory. only then can
there be a rational discussion.
--

Regards,

Eric Stevens