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

On Sun, 6 Jan 2019 10:35:05 -0500, Alan Browne
wrote:

On 2019-01-05 19:55, Eric Stevens wrote:
On Sat, 5 Jan 2019 09:32:36 -0500, Alan Browne
wrote:

On 2019-01-05 05:03, Eric Stevens wrote:
rOn Thu, 3 Jan 2019 11:26:55 -0500, Alan Browne
wrote:

On 2019-01-03 10:58, Peter Irwin wrote:
nospam wrote:
In article , Peter Irwin
wrote:

the issue was that dxo claimed that several cameras which have a 14 bit
adc could produce nearly 15 stops of dynamic range.

that's not possible.

You have to give up linear encoding, but sure it is possible.
It might be perfectly sensible to have a toe and shoulder to the
curve which would allow 15 stops of dynamic range encoded in 14 bits.

I do not know if that is what is happening, but it would be a reasonable
thing to do.

A major departure from linear encoding anywhere other than the toe and
shoulder would not be a good idea.

It used to be common to assume about 1.5 bits worth of noise to any ADC
sample so you'd have to account for that (even if less than 1.5 bits
worth, noise is ... noise).

Yours is the first answer which appears to throw light on the
difference of opinion.

No. Nospam said it clearly enough: there is no magic.

s all the painfully obvious stuff


In any case it is quite possible for the dynamic range of the sensor
to exceed the dynamic range of the system of encoding.

In which case the sensor maker would have been foolish to not put in a
16 bit ADC for the case at hand. It is far more likely that the sensor
does not have the DR and that the 14 bit ADC exceeds the DR of the
sensor. That is usually the way engineers do these sorts of things[1].

It could be that Nikon did not think that the slight overflow of DR
was worth striving for (too noisy at the ends?) and in any case
already had a perfectly good 14 bit ADC. In any case we don't know (or
I don't know) how DxO either defines or measure DR. Nor do we know
what Nikon does betwee the sensor and the output of the ADC. We are up
to our necks in speculation.

That 14 bits cannot yield 15 bits of DR is not speculation.
That the bottom bit or so of information from the sensor is rot, is not
speculation.

(I'd like to know how DxO's tests treat noise in the DR calculation.
Classically the DR should include noise as a denominator thereby
reducing the DR value further as noise increases).

"Compressing" (Stretching, really) any portion of the curve (toe and
shoulder included) means increased quantization noise, so not so sure
the alleged 15 stops would really translate well to image quality.

[1] Back in the days when ADC's were expensive devices, one would "right
size" the ADC number of bits for acceptable performance v. a cost goal.
That's not much of a consideration today at the 16 bit level if the
sensor had that sort of performance - just not at all likely.

In any case, there is no output device which can do justice to 14
stops. The image will always be compressed or clipped before viewing.

It still gives the photo "editor" more information to work with. How he
uses that to improve the overall image is his choice.

Quite true. Almost certainly the editor has to further compress they
dynamic range to produce an acceptable image on any viewing device. My
point is that if the sensor has a very large dynamic range there is no
reason why the camera software cannot do some form of pre-compressing
to get it down to 14 bits.
--

Regards,

Eric Stevens

On Sun, 6 Jan 2019 10:11:36 -0500, Alan Browne
wrote:

On 2019-01-05 22:59, Eric Stevens wrote:


It could be, or it could be at twice the shutter speed. But in this
case he hasn't increased the exposure. All he is doing is over
exposing.

1. You don't know his intent. Maybe 1 more stop is correct exposure for
his case.

2. How can you say "hasn't increased" but "is over exposing".

I was assuming that the given lens and shutter settings were ok for
ISO 100.

Talk about messy writing!

Agreed. Especially when using expressions such as "iso 200 is one stop
faster". ISO isn't one stop faster: it's one stop more sensitive. It's
even more confusing when one attributes speed to lenses. A lens isn't
'fast' as it isn't going anywhere. One has to be very careful when
discussing these matters to avoid confusion.
--

Regards,

Eric Stevens

On Sun, 6 Jan 2019 10:09:04 -0500, Alan Browne
wrote:

On 2019-01-05 19:33, Eric Stevens wrote:
On Wed, 02 Jan 2019 08:25:37 -0500, nospam
wrote:

In article , Eric Stevens
wrote:


https://expertphotography.com/unders...hotography-exp
osure/

The author of that article is using 'stop' when he should be using
'exposure value'. But lets not get into that in this thread. It's
confused enough already. :-)

equivalent.

Did the author attend the same school of technical writing that
trained you? He starts off with "In photography, a ‘f/stop’ is a
measurement of an exposure" and then launches into "... the infamous
shutter speed, ISO or aperture settings". A really confused beginning.

f/stop is not a measurement of exposure, but of lens opening. In
combination with shutter speed lens opening gives exposure.

Then he goes and writes "So, for example, suppose your camera’s
aperture is f/4, shutter speed is 1/100 and ISO is 100. If you keep
the aperture at f/4 and the shutter speed at 1/100 but you increased
the ISO to 200, you have increased the exposure by one stop" which is
utter nonsense. Changing the ISO without changing anything else does

To a photographer it is entirely correct. A physicist would say, "the
same number of photons hit the film/sensor" but a photographer will say
it exposed 1 stop more because of the increased sensitivity.

That's loose use of 'exposure'.

not affect the exposure one iota. With unchanged shutter speed and
unchanged lens opening the exposure is unchanged also.

... and so on he goes.

Never use a correct word when you can use an uninformed substitute. It
enables you to later select the meaning which best suits your line of
argument at the moment. :-)

I won't get into what a particular author wrote or how badly or well he
did it, but stating 100 - 200 ISO change as 1 stop more exposure is
entirely correct for a photographer.

I don't think its correct for anyone to say that but I am noy going to
continue arguing.
--

Regards,

Eric Stevens

In article , Eric Stevens
wrote:

It could be, or it could be at twice the shutter speed. But in this
case he hasn't increased the exposure. All he is doing is over
exposing.

1. You don't know his intent. Maybe 1 more stop is correct exposure for
his case.

2. How can you say "hasn't increased" but "is over exposing".

I was assuming that the given lens and shutter settings were ok for
ISO 100.

Talk about messy writing!

Agreed. Especially when using expressions such as "iso 200 is one stop
faster". ISO isn't one stop faster: it's one stop more sensitive.

it's both.

It's
even more confusing when one attributes speed to lenses. A lens isn't
'fast' as it isn't going anywhere.

lenses have long been described as fast or slow.

One has to be very careful when
discussing these matters to avoid confusion.

apparently so, since you're very confused.

On Thursday, January 3, 2019 at 10:58:25 AM UTC-5, Peter Irwin wrote:
nospam wrote:
In article , Peter Irwin
wrote:

the issue was that dxo claimed that several cameras which have a 14 bit
adc could produce nearly 15 stops of dynamic range.

that's not possible.

You have to give up linear encoding, but sure it is possible.
It might be perfectly sensible to have a toe and shoulder to the
curve which would allow 15 stops of dynamic range encoded in 14 bits.

Actually, that's just what I was thinking about when I last commented, and
its pretty straightforward to do for this circumstance:

"If value (high # photons in well) ... then assign value 14

"If value (low # photons in well) ... then assign value 0

For 1-13 in between, they have linear ranges.

The net result is that any value lower than "low #', it is assumed black,
and any value higher than "high #" is assigned white.


I do not know if that is what is happening, but it would be a reasonable
thing to do.

Quite reasonable when it puts more 'resolution' (bit values) to the target
range of highest interest.

I'll check with our resident physiologist specialist on the eye/perception, but
IIRC, the eye isn't a linear device, so it would make very much sense for
photography systems to have been mimicking a nonlinear curve since
before the invention of color film...


A major departure from linear encoding anywhere other than the toe and
shoulder would not be a good idea.

It depends on the application. Since we're effectively trying to produce
a product that is pleasing to the human eye, the encoding of the biological
system of the eye becomes part of the question, as does also of the next step
of the image display system, be it light based (monitors) or pigment (prints).


-hh

In article , -hh
wrote:

I'll check with our resident physiologist specialist on the eye/perception,
but
IIRC, the eye isn't a linear device, so it would make very much sense for
photography systems to have been mimicking a nonlinear curve since
before the invention of color film...

they do, and it's called gamma.

On 2019-01-06 23:09, Eric Stevens wrote:
On Sun, 6 Jan 2019 10:35:05 -0500, Alan Browne
wrote:

On 2019-01-05 19:55, Eric Stevens wrote:
On Sat, 5 Jan 2019 09:32:36 -0500, Alan Browne
wrote:

On 2019-01-05 05:03, Eric Stevens wrote:
rOn Thu, 3 Jan 2019 11:26:55 -0500, Alan Browne
wrote:

On 2019-01-03 10:58, Peter Irwin wrote:
nospam wrote:
In article , Peter Irwin
wrote:

the issue was that dxo claimed that several cameras which have a 14 bit
adc could produce nearly 15 stops of dynamic range.

that's not possible.

You have to give up linear encoding, but sure it is possible.
It might be perfectly sensible to have a toe and shoulder to the
curve which would allow 15 stops of dynamic range encoded in 14 bits.

I do not know if that is what is happening, but it would be a reasonable
thing to do.

A major departure from linear encoding anywhere other than the toe and
shoulder would not be a good idea.

It used to be common to assume about 1.5 bits worth of noise to any ADC
sample so you'd have to account for that (even if less than 1.5 bits
worth, noise is ... noise).

Yours is the first answer which appears to throw light on the
difference of opinion.

No. Nospam said it clearly enough: there is no magic.

s all the painfully obvious stuff


In any case it is quite possible for the dynamic range of the sensor
to exceed the dynamic range of the system of encoding.

In which case the sensor maker would have been foolish to not put in a
16 bit ADC for the case at hand. It is far more likely that the sensor
does not have the DR and that the 14 bit ADC exceeds the DR of the
sensor. That is usually the way engineers do these sorts of things[1].

It could be that Nikon did not think that the slight overflow of DR
was worth striving for (too noisy at the ends?) and in any case
already had a perfectly good 14 bit ADC. In any case we don't know (or
I don't know) how DxO either defines or measure DR. Nor do we know
what Nikon does betwee the sensor and the output of the ADC. We are up
to our necks in speculation.

That 14 bits cannot yield 15 bits of DR is not speculation.
That the bottom bit or so of information from the sensor is rot, is not
speculation.

(I'd like to know how DxO's tests treat noise in the DR calculation.
Classically the DR should include noise as a denominator thereby
reducing the DR value further as noise increases).

"Compressing" (Stretching, really) any portion of the curve (toe and
shoulder included) means increased quantization noise, so not so sure
the alleged 15 stops would really translate well to image quality.

[1] Back in the days when ADC's were expensive devices, one would "right
size" the ADC number of bits for acceptable performance v. a cost goal.
That's not much of a consideration today at the 16 bit level if the
sensor had that sort of performance - just not at all likely.

In any case, there is no output device which can do justice to 14
stops. The image will always be compressed or clipped before viewing.

It still gives the photo "editor" more information to work with. How he
uses that to improve the overall image is his choice.

Quite true. Almost certainly the editor has to further compress they
dynamic range to produce an acceptable image on any viewing device. My
point is that if the sensor has a very large dynamic range there is no
reason why the camera software cannot do some form of pre-compressing
to get it down to 14 bits.

Which is lossy. 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.

--
"2/3 of Donald Trump's wives were immigrants. Proof that we
need immigrants to do jobs that most Americans wouldn't do."
- unknown protester

On 2019-01-06 23:17, Eric Stevens wrote:
On Sun, 6 Jan 2019 10:11:36 -0500, Alan Browne
wrote:

On 2019-01-05 22:59, Eric Stevens wrote:


It could be, or it could be at twice the shutter speed. But in this
case he hasn't increased the exposure. All he is doing is over
exposing.

1. You don't know his intent. Maybe 1 more stop is correct exposure for
his case.

2. How can you say "hasn't increased" but "is over exposing".

I was assuming that the given lens and shutter settings were ok for
ISO 100.

Talk about messy writing!

Agreed. Especially when using expressions such as "iso 200 is one stop
faster". ISO isn't one stop faster: it's one stop more sensitive. It's
even more confusing when one attributes speed to lenses. A lens isn't
'fast' as it isn't going anywhere. One has to be very careful when
discussing these matters to avoid confusion.

When someone tells me fast lens I just assume it's fat, huge aperture
and expensive (and usually damned good).

The expression has been around far longer than I've been shooting.

--
"2/3 of Donald Trump's wives were immigrants. Proof that we
need immigrants to do jobs that most Americans wouldn't do."
- unknown protester

On 2019-01-06 23:20, Eric Stevens wrote:
On Sun, 6 Jan 2019 10:09:04 -0500, Alan Browne
wrote:

On 2019-01-05 19:33, Eric Stevens wrote:
On Wed, 02 Jan 2019 08:25:37 -0500, nospam
wrote:

In article , Eric Stevens
wrote:


https://expertphotography.com/unders...hotography-exp
osure/

The author of that article is using 'stop' when he should be using
'exposure value'. But lets not get into that in this thread. It's
confused enough already. :-)

equivalent.

Did the author attend the same school of technical writing that
trained you? He starts off with "In photography, a ‘f/stop’ is a
measurement of an exposure" and then launches into "... the infamous
shutter speed, ISO or aperture settings". A really confused beginning.

f/stop is not a measurement of exposure, but of lens opening. In
combination with shutter speed lens opening gives exposure.

Then he goes and writes "So, for example, suppose your camera’s
aperture is f/4, shutter speed is 1/100 and ISO is 100. If you keep
the aperture at f/4 and the shutter speed at 1/100 but you increased
the ISO to 200, you have increased the exposure by one stop" which is
utter nonsense. Changing the ISO without changing anything else does

To a photographer it is entirely correct. A physicist would say, "the
same number of photons hit the film/sensor" but a photographer will say
it exposed 1 stop more because of the increased sensitivity.

That's loose use of 'exposure'.

Not at all. Aside from setting lighting, those are the three variables
that a photographer can play with to achieve his goals. Thinking in
"stops" is entirely natural and reasonable. If you prefer "EV" then I'm
not criticizing anyone.


not affect the exposure one iota. With unchanged shutter speed and
unchanged lens opening the exposure is unchanged also.

... and so on he goes.

Never use a correct word when you can use an uninformed substitute. It
enables you to later select the meaning which best suits your line of
argument at the moment. :-)

I won't get into what a particular author wrote or how badly or well he
did it, but stating 100 - 200 ISO change as 1 stop more exposure is
entirely correct for a photographer.

I don't think its correct for anyone to say that but I am noy going to
continue arguing.

This is usenet. You have a life sentence.


--
"2/3 of Donald Trump's wives were immigrants. Proof that we
need immigrants to do jobs that most Americans wouldn't do."
- unknown protester

On Sun, 6 Jan 2019 10:13:09 -0500, Alan Browne
wrote:

On 2019-01-04 18:58, Eric Stevens wrote:
On Fri, 4 Jan 2019 16:16:05 -0500, Alan Browne
wrote:

On 2019-01-02 04:16, Eric Stevens wrote:
On Wed, 2 Jan 2019 07:48:13 +0000, RJH wrote:

On 02/01/2019 01:38, nospam wrote:
In article , Eric Stevens
wrote:

You are obviously wedded to 1 stop per bit. Why is that?

math.

Why for example can you not have 2 stops per bit, or pi stops per bit?
As long as you scale the entire brightness range with the available 14
stops.

because it doesn't work that way.

think about what a stop means.


FWIW, I don't follow the linearity - in fact I've often wondered why
aperture, ISO and shutter speed aren't infinitely variable, especially
with digital. This article takes me closer to understanding:

https://expertphotography.com/understanding-fstops-stops-in-photography-exposure/

The author of that article is using 'stop' when he should be using
'exposure value'. But lets not get into that in this thread. It's
confused enough already. :-)

There is no difference at all between an EV and a stop of any of the
three independent variables of ISO, exposure period and aperture.

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,
or possibly very fine steps in speed priority or auto modes.

I bow to your superior knowledge of my equipment.
--

Regards,

Eric Stevens