Finally got to the point where no new camera holds my interest(waiting for specific offering)

In article , Eric Stevens
wrote:

This illustrates the disadvantage of not using the language with
precision. As I said, all my lenses make use of f/numbers which are a
measure of stops. Your thoughts have jumped the rails and are now
talking about the intervals of Exposure Value of which the camera is
capable. The exposure value may be used to set lens aperture, shutter
speed or ISO. They are not identical to stops.

they absolutely are.

So I double the shutter speed. I have halved the exposure value but I
haven't affected the stop setting.

Exposure value is really a measure of the brightness irrespective of the
shutter speed or aperature. Which is why sensor can have EV values which
aren;t referenced to shutter speeds or stops.

Exposure value is a measure of the total quantity of light falling on
the sensor. i.e its a function of lens aperture and length of time of
exposure.

and for a given iso.

except what you're missing is that the *difference* is also measured in
ev (or stops).

In article , Eric Stevens
wrote:



They most definitely are, and probably 1/2 or 1/3 steps of EV as
well, [1] ---
or possibly very fine steps in speed priority or auto modes.

I bow to your superior knowledge of my equipment.

Do your lenses have stops?

Yes.

Exactly. So they are indeed calibrated in EV. ([1] above).

No. EVs can be deduced. See
https://en.wikipedia.org/wiki/Exposure_value

"In photography, exposure value (EV) is a number that represents a
combination of a camera's shutter speed and f-number, such that all
combinations that yield the same exposure have the same EV (for any
fixed scene luminance)."

Finding some convenient words doesn't obviate the facts. Your camera
and lenses are calibrated in EV. What words are used (stops for
example) do not matter at all.

Dear me! I can change the EV to which my camera is set without
changing the lens aperture.

you should be able to.

My lenses are not calibrated in EVs.

actually, they're calibrated in 1/3 evs, unless they're old, when it
wasn't possible to be that accurate.

Further, lenses do not determine EVs on their own. It is also
necessary to set a shutter speed.

and iso.

In article , Eric Stevens
wrote:

Theey do not specify their algorithms in the article.

Exactly.

So?

the so is that you have no idea whether any of their algorithms are
good or bad and how much they are influenced by cash.

That's pure speculation inspired by malice.

nope.

there's a lot of evidence that they can be bought, which is a problem.

it's a very interesting algorithm when those who partner with dxo get
better results than those who do not...

What do you expect? Those who study the syllabus get better exam
results than those who don't.

more accurately, paying to get a copy of the exam questions and then
memorizing them, then pretending that acing the test means you know
more than the other students, who really did study hard and really do
know the material, but got a couple of questions wrong.

for all anyone knows, they roll dice and whatever number comes up is
the number they use...

In that case you can't accuse them of bias.

true, but what you're missing is such a method would be meaningless,
much like the numbers they currently provide.

so maybe that is what they're doing after all...

In article , Eric Stevens
wrote:

But a moot point IMO. I doubt the sensor mentioned has
14 bits of DR in the first place. Esp. once you account for noise.

Well, DxO measure 14.3 but what exactly that means is unknown. But if
they made that specific statement then I would expect they must have
grounds.

it means their test methodology is worthless or they're intentionally
lying.

Or that you have failed to understand what they are doing.

Your other post ends with a statement to the effect that DxO don't say
what their algorithms are doing, so nospam certainly didn't fail anything.

nospam will fail to understand what they are doing if he doesn't know
what they are doing. That applies to everyone.

it's not me who is failing to understand what's going on.

Are you claiming to understand what they are doing when you don't know
what it is?

no.

In the end physics is physics and there is no way they are getting more
DR than the sensor offers. Not even the bit depth of it.

According to nospam they are claiming a DR of 14.3 for the sensor of
the D800. As they said in the link that I posted which has somehow got
snipped "Maximum dynamic range is the greatest possible amplitude
between light and dark details a given sensor can record ...".

which is limited to 14 stops in an ideal world.
in the real world, it's less.

Read my recent response to Alan Browne.

i did. read my response to your response.

rOn Thu, 10 Jan 2019 22:45:01 -0600, Bill W
wrote:

On Fri, 11 Jan 2019 16:52:47 +1300, Eric Stevens
wrote:

On Thu, 10 Jan 2019 07:39:32 -0500, Alan Browne
wrote:

On 2019-01-10 04:05, Eric Stevens wrote:
On Tue, 8 Jan 2019 08:31:05 -0500, Alan Browne
wrote:

On 2019-01-08 03:54, Eric Stevens wrote:
On Mon, 07 Jan 2019 23:42:07 -0500, nospam
wrote:

In article , Eric Stevens
wrote:

But a moot point IMO. I doubt the sensor mentioned has
14 bits of DR in the first place. Esp. once you account for noise.

Well, DxO measure 14.3 but what exactly that means is unknown. But if
they made that specific statement then I would expect they must have
grounds.

it means their test methodology is worthless or they're intentionally
lying.

Or that you have failed to understand what they are doing.

Your other post ends with a statement to the effect that DxO don't say
what their algorithms are doing, so nospam certainly didn't fail anything.

nospam will fail to understand what they are doing if he doesn't know
what they are doing. That applies to everyone.

In the end physics is physics and there is no way they are getting more
DR than the sensor offers. Not even the bit depth of it.

According to nospam they are claiming a DR of 14.3 for the sensor of
the D800. As they said in the link that I posted which has somehow got
snipped "Maximum dynamic range is the greatest possible amplitude
between light and dark details a given sensor can record ...".

1. A 14 bit sensor cannot, possibly, record 14.3 DR.

Please read what I am about to write and give it deep consideration
before you reply.

_There_is_no_such_thing_as_a_14_bit_sensor_! Or a 12 bit for that
matter. The sensors which we are considering are *analog* devices
which are not digital in their operation.

12 or 14 bits only come into it after the analog signal is stripped
from the sensor and (only then) passed through an analogue to a
digital convertor (ADC).

A 14 bit ADC can output 16,384 distinct numerical values and the
analog output of the sensor has to be mapped to this range. It doesn't
matter what the Dynamic Range of the sensor may be. It has to be
mapped to the numerical scale of the output of the ADC. It is
perfectly feasible to map an analogue dynamic range to 14 bits (o12
(or 8)). Not withstanding what else has been written in this thread
the choice of the number of bits used to encode the sensor's output
does not affect the _sensor's_ dynamic range.

But the issue is not the sensor's DR, it's the camera's DR. The output
of the camera is the output of the ADC - not the sensor, and that ADC
is limited to 14 stops as designed.

It normally is, but the items which started all this e.g.
https://www.dxomark.com/Cameras/Nikon/D850 listed a dynamic range of
14.8 EVs for the D810 and similar figures for other cameras. This is
what prompted nospam to call them liars and crooks etc.

I went out and found
https://www.dxomark.com/dxomark-came...ol-and-scores/
(which I posted) and pointed out that the article described the
general nature of the test for dynamic range.

Under the heading of "Noise and Dynamic Range" they said:

"We measure Noise using a transmission target placed on top of a
uniform light box. The transmission target is an in-house design
made of a thick black plastic plate with precision-drilled holes.
These holes (or “patches�) are equipped with range of neutral
density filters designed to absorb light in the same way for all
wavelengths. The filters are made of pure optical glass with no
structures that could be measured as noise. Other image quality
measurement solutions make use of printed targets, but we believe
such targets are inappropriate for noise measurements, as the
intrinsic noise pattern of the paper can be recorded by the tested
camera and then confused with a noise pattern."

This was accompanied by a photograph showing the general setup.

Earlier in the article they said:

"Dynamic range corresponds to the ratio between the highest
brightness a camera can capture (saturation) and the lowest
brightness it can capture (which is typically when noise becomes
more important than the signal — that is, a signal-to-noise ratio
below 0 dB). A value of 12 EV is excellent, with differences below
0.5 EV usually not noticeable. Dynamic range is an open scale."

Particularly note that last sentence.

In the first quote DxO explain their steps to avoid spurious noise.
That alone may be sufficient to give rise to a wider useful dynamic
range than may be measured by other labs.

But note, they are determining a camera's ability to record a
calibrated range of luminances. This is entirely a test of the sensor
and has nothing to do with the number of bits later output by the ADC.

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.
--

Regards,

Eric Stevens

On Fri, 11 Jan 2019 00:18:26 -0500, nospam
wrote:

In article , Eric Stevens
wrote:

In the end physics is physics and there is no way they are getting more
DR than the sensor offers. Not even the bit depth of it.

According to nospam they are claiming a DR of 14.3 for the sensor of
the D800. As they said in the link that I posted which has somehow got
snipped "Maximum dynamic range is the greatest possible amplitude
between light and dark details a given sensor can record ...".

1. A 14 bit sensor cannot, possibly, record 14.3 DR.

Please read what I am about to write and give it deep consideration
before you reply.

_There_is_no_such_thing_as_a_14_bit_sensor_! Or a 12 bit for that
matter. The sensors which we are considering are *analog* devices
which are not digital in their operation.

12 or 14 bits only come into it after the analog signal is stripped
from the sensor and (only then) passed through an analogue to a
digital convertor (ADC).

A 14 bit ADC can output 16,384 distinct numerical values and the
analog output of the sensor has to be mapped to this range. It doesn't
matter what the Dynamic Range of the sensor may be. It has to be
mapped to the numerical scale of the output of the ADC. It is
perfectly feasible to map an analogue dynamic range to 14 bits (o12
(or 8)). Not withstanding what else has been written in this thread
the choice of the number of bits used to encode the sensor's output
does not affect the _sensor's_ dynamic range.

the sensor's dynamic range is not what's being measured.

You didn't read
https://www.dxomark.com/dxomark-came...ol-and-scores/
or if you did, you didn't understand it.

dxo is reporting the dynamic range of various *cameras*.

and even if you ignore the 14 bit issue, their numbers are highly
suspect.

the nikon d800 and d800 are identical cameras, the only difference
being the lack of an anti-alias filter on the d800e, something which
does not affect dynamic range (only aliasing). thus, the results should
be *the* *same* (other than alias artifacts on high frequency content).

Light passes through the filter which affects the spectrum detected by
the sensor. Of course this will affect the dynamic range.

dxo claims that the d800 has 14.4 stops dynamic range and the d800e has
14.3 stops.

Even ignoring error bars, this is not at all surprising.

other test results also differ between the two cameras. they also claim
that the d800e has a higher low light iso, again, with the same sensor,
which is *opposite* to what one would expect if it has less dynamic
range.

Just in case you hadn't read it:

"We measure the luminance of each uniform area (patch) on the chart
using a certified luminance-meter, and then input the values into
DxO Analyzer software. Once we have measured the target and
calibrated the DxO Analyzer software, we shoot test images of the
noise target at different ISO settings, and measure the Noise for
each color channel of the target image (R, Gr, Gb, B). We compute
the mean gray level and noise values for each patch and for all
images shot at different ISO settings, and finally interpolate
these numerical values for all gray levels to calculate and plot
signal-to-noise ratio (SNR) curves, from which DxO Analyzer
extracts the SNR 18%, the dynamic range, and the tonal range."


that alone shows something is very, very wrong with their tests, and to
your point, is *not* a measure of the sensor itself.

https://www.dxomark.com/Cameras/Nikon/D800
https://www.dxomark.com/Cameras/Nikon/D800E
--

Regards,

Eric Stevens

On Fri, 11 Jan 2019 00:18:31 -0500, nospam
wrote:

In article , Eric Stevens
wrote:



They most definitely are, and probably 1/2 or 1/3 steps of EV as
well, [1] ---
or possibly very fine steps in speed priority or auto modes.

I bow to your superior knowledge of my equipment.

Do your lenses have stops?

Yes.

Exactly. So they are indeed calibrated in EV. ([1] above).

No. EVs can be deduced. See
https://en.wikipedia.org/wiki/Exposure_value

"In photography, exposure value (EV) is a number that represents a
combination of a camera's shutter speed and f-number, such that all
combinations that yield the same exposure have the same EV (for any
fixed scene luminance)."

Finding some convenient words doesn't obviate the facts. Your camera
and lenses are calibrated in EV. What words are used (stops for
example) do not matter at all.

Dear me! I can change the EV to which my camera is set without
changing the lens aperture.

you should be able to.

My lenses are not calibrated in EVs.

actually, they're calibrated in 1/3 evs, unless they're old, when it
wasn't possible to be that accurate.

Further, lenses do not determine EVs on their own. It is also
necessary to set a shutter speed.

and iso.

You say that my lenses are calibrated in EVs and then agree there are
factors additional to the lens which determine EV. Is my lens somehow
prescient or are you an idiot?
--

Regards,

Eric Stevens

On Fri, 11 Jan 2019 00:18:27 -0500, nospam
wrote:

In article , Eric Stevens
wrote:

It may be hair-splitting but none of my lenses are calibrated in
EVs.

They most definitely are, and probably 1/2 or 1/3 steps of EV as
well,
[1] ---
or possibly very fine steps in speed priority or auto modes.

I bow to your superior knowledge of my equipment.

Do your lenses have stops?

Yes.

Exactly. So they are indeed calibrated in EV. ([1] above).

No. EVs can be deduced. See
https://en.wikipedia.org/wiki/Exposure_value

"In photography, exposure value (EV) is a number that represents a
combination of a camera's shutter speed and f-number, such that all
combinations that yield the same exposure have the same EV (for any
fixed scene luminance)."

from that link,
Exposure value is also used to indicate an interval on the
photographic exposure scale, with a difference of 1 EV corresponding
to a standard power-of-2 exposure step, commonly referred to as a
stop.

it would be wise to learn the basics of photography so that you
actually understand what it is you're reading before commenting
further.

It might be commonly referred to as a stop but that is just plain
sloppy usage.

it's not sloppy at all. in fact, it's exactly correct.

On that basis you might as well call the shutter speed a
stop or even the ISO a stop.

the *difference* is called a stop, aka 'interval on the photographic
exposure scale':
Exposure value is also used to indicate an interval on the
photographic exposure scale, with a difference of 1 EV corresponding
to a standard power-of-2 exposure step, commonly referred to as a
stop.

iso 800 is one stop more sensitive than iso 400.
1/250th is one stop less light than 1/125th.
f/4 is one stop more light than f/5.6.

Assuming noting else changes.

I initially mentioned this topic in passing when I referred to sloppy
writing. I didn't call for examples.

unfortunately for you, examples were provided and they show that you
don't understand it.

That's the problem with sloppy writing: people frequently don't
understand it.
--

Regards,

Eric Stevens

On Fri, 11 Jan 2019 00:18:28 -0500, nospam
wrote:

In article , Eric Stevens
wrote:


EV's are equivalent to stops for any purpose related to exposure.

I can change exposure value without changing the stop setting.

No ****. That's sort of the point.

It's my point. Stops aren't exposure values. Exposure values are not
stops.

they are.

Lets leave it at that.

ok, but you saying so doesn't make it correct.

Allright then. Please explain to your readers how you set a lens to an
EV of 20.
--

Regards,

Eric Stevens

On Fri, 11 Jan 2019 00:18:29 -0500, nospam
wrote:

In article , Eric Stevens
wrote:


This illustrates the disadvantage of not using the language with
precision. As I said, all my lenses make use of f/numbers which are a
measure of stops. Your thoughts have jumped the rails and are now
talking about the intervals of Exposure Value of which the camera is
capable. The exposure value may be used to set lens aperture, shutter
speed or ISO. They are not identical to stops.

EV's are equivalent to stops for any purpose related to exposure.

I can change exposure value without changing the stop setting.

you are confusing f/stop with stop.

'stop' is an abreviated way of referring to an obsolete way of
changing lens aperture. It's use as a reference to lens aperture is
now normal.

doing so is what you call 'sloppy'.

you're confusing stop, f/stop and aperture and also ev.

You are crackers. I'm trying quite hard to get you to make a
distinction.
--

Regards,

Eric Stevens