In article , Eric Stevens
wrote:

I wasn 't going answer this until I realised you had done some crude
editing of the article to which you were replying. In other words a
blatant lie.

nope. i snipped to eliminate irrelevant crap, other than yours, that is.

consider it 'noise reduction', although the dominant noise source is
not what was removed...

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?

you're confused.

https://whatis.techtarget.com/defini...yquist-Theorem

"The Nyquist Theorem, also known as the sampling theorem, is a
principle that engineers follow in the digitization of analog
signals. For analog-to-digital conversion (ADC) to result in a
faithful reproduction of the signal, slices, called samples, of the
analog waveform must be taken frequently. The number of samples per
second is called the sampling rate or sampling frequency.

Any analog signal consists of components at various frequencies. The
simplest case is the sine wave, in which all the signal energy is
concentrated at one frequency. In practice, analog signals usually
have complex waveforms, with components at many frequencies. The
highest frequency component in an analog signal determines the
bandwidth of that signal. The higher the frequency, the greater the
bandwidth, if all other factors are held constant.

Suppose the highest frequency component, in hertz, for a given
analog signal is fmax. According to the Nyquist Theorem, the
sampling rate must be at least 2fmax, or twice the highest analog
frequency component. The sampling in an analog-to-digital converter
is actuated by a pulse generator (clock). If the sampling rate is
less than 2fmax, some of the highest frequency components in the
analog input signal will not be correctly represented in the
digitized output. When such a digital signal is converted back to
analog form by a digital-to-analog converter, false frequency
components appear that were not in the original analog signal. This
undesirable condition is a form of distortion called aliasing."

Now, bearing in mind that once the shutter has closed, a sensor site
sits there fat and happy (or thin and misrable) with as many photons
as the lens has thought to direct its way. No change. It's constant.
The frequency of the signal being sampled (i.e the number of photons
in the cell) is zero. According to Nyquist the sampling frequency must
be 2 x zero = zero. In other words it only needs to be sampled once.

you're even more confused than i thought.

Now what were you saying about sampling theory?

that it applies and there's no escaping it.

unless you know something the rest of the world does not, that is, but
if you really can disprove nyquist and sampling theory as we know it,
then stop babbling on usenet and go write a paper, give some talks and
change the world as we know it.


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)."?

nope.

i mean this pretty little pictu
https://3.img-dpreview.com/files/g/TS560x560~1835042.jpg
from this post, which is the second post in the thread:
https://www.dpreview.com/forums/post/41016086

Oh you persistent dummy! That's talking about the DR range coded into
the digital output signal by the ADC.

which shows that a 14 bit adc limits it to 14 stops. imagine that.

It is not, never was, and never
will be the same as the DR of the analog input signal. (Maybe that's
too sweeping a statement but you get the drift).

otherwise described as "the dynamic range is limited by the adc".

you said:
DR vs number of bits is touched upon but no
one has suggested that sensor DR is limited by bit number.

except that someone did, with a nice picture too. so much for that idea.


it's even marked in evs, although that will no doubt cause you massive
confusion.

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

nope, what i told you is that the sensor output *could* be scaled, but
it isn't, therefore what you've said is not applicable.

OK. I will accept that. But I expect that's why you have snipped:

nope. i snipped it because it's not correct.

you only quoted it because it says the same crap you've been parroting.