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

On Fri, 11 Jan 2019 10:28:21 -0500, nospam
wrote:

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. 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.

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

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.

https://www.dxomark.com/Cameras/Nikon/D50
https://www.dxomark.com/Cameras/Nikon/D70
--

Regards,

Eric Stevens

On Fri, 11 Jan 2019 12:51:28 -0500, Alan Browne
wrote:

On 2019-01-11 10:28, nospam wrote:
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.


Got that Eric?

What is 'it'? The DR of the sensor or the DR of the output of the ADC?
--

Regards,

Eric Stevens

On Fri, 11 Jan 2019 11:15:19 -0600, Bill W
wrote:

On Fri, 11 Jan 2019 21:30:23 +1300, Eric Stevens
wrote:

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.

Well that's exactly what I said. If they are publishing the DR of the
sensor, why would any photographer care about that, if the DR is then
limited by the ADC? The usable output of any camera we buy is all we
care about.

There is no reason why the DR of the sensor should not be compressed
to make it fit within the limits of the ADC. After all, in processing
it's going to be further compressed (and probably clipped) for viewing
on a screen and even further compressed (and probably clipped) when
output to a display device or printer. I presume the intention is that
the original information be preserved as much as possible as far down
the processing stream as is possible.

DXO's results are at best misleading, whether it's malicious or not.

I suspect that the problem is that they are working in an area which
few people properly understand. e.g.:
https://corp.dxomark.com/wp-content/...onCapacity.pdf
and
https://corp.dxomark.com/wp-content/...enes_small.pdf
or http://tinyurl.com/yaaf4o6s
--

Regards,

Eric Stevens

On Fri, 11 Jan 2019 10:28:19 -0500, nospam
wrote:

In article , Eric Stevens
wrote:

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.

nonsense. an aa filter has *zero* effect on dynamic range.

You know that do you? Show me the data.

Google shows that a hell of a lot of work has been done on the
spectral properties of anti-aliasing filters. You should write to all
the authors and tell them they are wasting their time.

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.

it's very surprising that two identical sensors (other than an aa
filter, which has no effect except for aliasing) in identical cameras
with identical electronics have different results, without any
explanation as to why.

That it has no effect except for aliasing is classic nospam. It
reminds me of the discussion when you assumed that in Windows the
'print' function sent a file straight to the printer without anything
going on in between. In fact all kinds of things may be going on as
well the one thing that you have in mind.
--

Regards,

Eric Stevens

On Fri, 11 Jan 2019 12:42:13 -0500, Alan Browne
wrote:

On 2019-01-10 22:52, Eric Stevens wrote:
On Thu, 10 Jan 2019 07:39:32 -0500, Alan Browne
wrote:

On 2019-01-10 04:05, Eric Stevens wrote:

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).

Now you're being silly.

The whole point of the ADC is to sample the analog sensor.

Constrain that to 14 bits and that's all you get. The whole point of
"more bits" in the ADC is not to find "bright" signal, but to sample
down deep in the very smallest shreds of the darkest part of the signal.

All of which is completely true. But how deep down are the shreds of
the darkest part of the signal. And how bright is the brightest part
of the signal before it overflows into blooming? It is the difference
between these that determines the dynamic range of the sensor. The
fact that the DR is scaled to 14 bits is of secondary consideration.
If 14 bits is all that ammters why go to all the trouble and expense
of developing high DR sensors? Let's have a cheap sensor and hang it
on a 14 bit ADC.

For that matter, what do you expect DxO to measure? Do you want the DR
of the 14 bit DR data, or do you want to know the DR that the sensor
can capture?

Even if the sensor itself were capable of more than 14 bits of real
honest to goodness signal (not including noise) then declaring a camera
as being more sensitive than its ADC can deliver is plain wrong (not to
mention: noise).

THis comes back to the question of the scaling of the DR for input to
the ADC. The dynamic range of any sensor can be chopped up into 16,384
segments for coding with a 14 bit data stream. There is no direct
connection between the sensors DR and the number of segments into
which you want to chop it for digitizing. (Basically, the minimum
number of bits is that to avoid banding.)

Point is the engineers (most probably) put in an ADC that sampled a
slight more deeper than the practical DR of the analog sensor - ie: they
KNOW that anything deeper is just plain random numbers (aka: NOISE).

"It Ain’t What You Don’t Know That Gets You Into Trouble. It’s What
You Know for Sure That Just Ain’t So." Apparently DxO know more than
what appears to be the current common understanding. If you read their
technical publications you may discover that DxO calculates DR in
terms of all three colors (RGB) evaluated against particular criteria
which I have not yet seen stated.

Apart from anything else three streams of color data (RGB) coded in 14
bits each may transmit more DR information than can a single 14 bit
stream. It is quite conceivable that that the data stream from the
Nikon D800 is evaluated by the proprietary Nikon RAW decoder in such a
way that it recovers a greater depth of data than can be carried by
simple 14 bit data. I don't know. I suspect that you don't know and I
am confident that nospam will deny the very possibility of there being
anything to know with his dying breath. :-)

For light relief see
https://graphics.stanford.edu/course...rs-24apr14.pdf
--

Regards,

Eric Stevens

On Fri, 11 Jan 2019 12:43:32 -0500, Alan Browne
wrote:

On 2019-01-10 22:55, Eric Stevens wrote:
On Thu, 10 Jan 2019 07:41:14 -0500, Alan Browne
wrote:

On 2019-01-10 04:08, Eric Stevens wrote:
On Tue, 8 Jan 2019 08:29:29 -0500, Alan Browne
wrote:

On 2019-01-08 04:02, Eric Stevens wrote:

Theey do not specify their algorithms in the article.

Exactly.

So?

Not clear enough, huh? They don't show their algorithms (proprietary, I
assume). OTOH, the claim of 14.3 DR in the face of a 14 bit sensor and
no apparent accounting for noise is bad fish.

That clear enough?

EOD for me.

Please read my latest response and consider ...

I just did and you're grasping at straws.

If you say so.
--

Regards,

Eric Stevens

On Fri, 11 Jan 2019 10:28:22 -0500, nospam
wrote:

In article , Eric Stevens
wrote:


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?

ad hominem.

You mean there is another choice? If I accept what you say its got to
be one or the other.
--

Regards,

Eric Stevens

On Fri, 11 Jan 2019 12:44:39 -0500, Alan Browne
wrote:

On 2019-01-10 23:04, Eric Stevens wrote:
On Thu, 10 Jan 2019 07:44:43 -0500, Alan Browne
wrote:

On 2019-01-10 04:17, Eric Stevens wrote:
On Tue, 8 Jan 2019 08:32:40 -0500, Alan Browne
wrote:

On 2019-01-08 04:04, Eric Stevens wrote:
On Mon, 7 Jan 2019 16:57:44 -0500, Alan Browne
wrote:

On 2019-01-07 16:19, Eric Stevens wrote:
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, [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. My lenses are not calibrated in EVs.

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

Wow! You could pass Photography 101, chapter 3 (Basics of exposure).

CONGRATS!

Now you have followed me that far, you may be interested to see
https://upload.wikimedia.org/wikiped...Ib_with_EV.jpg

Notice how the bottom of the shutter speed ring has a pointer with
which you can set the EV. That enables the aperture ring (dimly seen
behind the pointer) to be moved in synchronism with the shutter speed
ring so as to maintain constant the preset EV. This is an early
pre-prescient camera. According to nospam modern cameras don't need
the EV to be set. The aperture ring knows the EV all on it's own.
--

Regards,

Eric Stevens

On Fri, 11 Jan 2019 10:28:23 -0500, nospam
wrote:

In article , Eric Stevens
wrote:


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.

it doesn't matter what else changes. they're independent statements.

iso 800 is one stop more sensitive than iso 400.

Providing no one fiddles with the shutter speed.

1/250th is one stop less light than 1/125th.

Providing no one fiddles with aperture setting.

f/4 is one stop more light than f/5.6.

That's about the only thing which is correct.

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.

your lack of understanding is not due to sloppy writing.

But you would say that, wouldn't you?
--

Regards,

Eric Stevens

On Fri, 11 Jan 2019 10:28:24 -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.

asking such a question shows you do not understand the topic.

I do understand the topic.

I understand the mistake you are making.

I also understand that you will never admit to being wrong and will
never explain to your readers how you set a lens to an EV of 20.

The problem is that you have somehow conflated the square root of 2
with the term 'stop'.
--

Regards,

Eric Stevens