Steps From Levels?

Wolfgang Weisselberg wrote:
Wilba wrote:
Wolfgang Weisselberg wrote:
Wilba wrote:

[Snip heaps of irrelevant insolent trolling.]

You forgot insubordination, King "goalpost shifter" Wilba.

Insubordination can only exist within an authoritative relationship. I find
it strange that you think I have the right to tell you what to do. :- )

Then you should relearn it.

You don't have the right to tell me what to do either. :- )

And without some objective measure, how would I know if I can?

You happen to have a camera, probably with a center or spot mode.
It can be used as a light meter with enough accuracy for that task.

If you try it I expect that unless you have a very different camera and
monitor to mine, you'll found it quite unsatisfactory.

Stop is an aperture-specific step, so although it's conventional
to do so, it's misleading to talk about stops of shutter speed,
ISO, or exposure compensation.

If you say so. Source? Or is that just your personal opinion?

I first came across the logically correct nomenclature in the early '80s, in
a long-forgotten photography book.

Without actually explaining how "stop" came to be associated with apertures,
this article - http://en.wikipedia.org/wiki/Exposure_value - complies with
the principle expressed in its footnote, "In optics, the term "stop"
properly refers to the aperture itself, while the term "step" refers to a
division of the exposure scale. Some authors, e.g., Davis (1993, 13), prefer
the term "stop" because they refer to steps (e.g., on a step tablet) that
are other than powers of 2. ISO standards generally use "step", while
photographers normally use "stop"."

Other instances? "Within any exposure factor (Exposure Value, film speed,
aperture, shutter speed) each step is double (or half of) the preceding
step." (http://www.fredparker.com/ultexp1.htm)

On the origin of "stop" - "The term ['one stop'] most directly relates to
aperture. It goes back to the time when cameras were first equipped for
control of aperture. Commonly, a metal plate carrying a number of holes of
different diameter passed through a transverse slot in the lens barrel. It
was said to "stop down" the lens aperture, and the different holes were said
to be "stops". The photographer moved the plate to put into place the
appropriate stop for a particular exposure. Commonly, successive holes had
areas that differed by 2:1. Thus a 2:1 change in aperture area came to be
known as a "one stop" change."
(http://doug.kerr.home.att.net/pumpkin/APEX.pdf)

To argue your position, you'd have to explain how expressions like "stop
down the shutter" (as an action), or "ISO stop" (as a noun phrase), make
literal sense. And to anticipate your retort, the repeated misuse of a
technical term to represent something else doesn't make that usage correct.

If you knew the answer all along, why didn't you just give it at an
appropriate time? :- )

Because you wanted to measure, nothing about roughly ...

"... measure or determine the number of exposure steps [zones] ...". There's
nothing in my question or the subsequent discussion that says "number" has
to be more precise than one significant digit. You're arguing against your
own unfounded assumptions and prejudices.

--- and my point still stands: will your image in it's later
representation
have 8 stops of range? Can your prints even deliver 8 ranges?

The image on the monitor is the final representation.

So what is the difference between 0 and 255 in the *final*
represenation of the image?

Eight steps.

Wilba wrote:
Wolfgang Weisselberg wrote:
Wilba wrote:
Wolfgang Weisselberg wrote:
Wilba wrote:

[Snip heaps of irrelevant insolent trolling.]

You forgot insubordination, King "goalpost shifter" Wilba.

Insubordination can only exist within an authoritative relationship. I find
it strange that you think I have the right to tell you what to do. :- )

I don't think so, but you quite behaved like it was the case.

Then you should relearn it.

You don't have the right to tell me what to do either. :- )

If English isn't your first language, you are excused from not
noticing any differences between "you should", "you must" and
"do it or else". :-

And without some objective measure, how would I know if I can?

You happen to have a camera, probably with a center or spot mode.
It can be used as a light meter with enough accuracy for that task.

If you try it I expect that unless you have a very different camera and
monitor to mine, you'll found it quite unsatisfactory.

It works well enough.
It also shows the monitor doesn't produce 8 an stop range between
0,0,0 and 255,255,255. Yes, calibrated monitor. Wheee --- out
of the window goes your assumption. As I said, your calculations
and musings depend too much on unwarranted, unchecked assumptions.

Stop is an aperture-specific step, so although it's conventional
to do so, it's misleading to talk about stops of shutter speed,
ISO, or exposure compensation.

If you say so. Source? Or is that just your personal opinion?

I first came across the logically correct nomenclature in the early '80s, in
a long-forgotten photography book.

Nomenclature is rarely logical, since it usually grows with the
field it describes. Unless it's invented more or less
completely at the start ... no chance.

[...]
d)are other than powers of 2. ISO standards generally use "step", while
photographers normally use "stop"."

I don't know if you are a photographer, but I am virtually
certain you are no ISO standard.

To argue your position, you'd have to explain how expressions like "stop
down the shutter" (as an action), or "ISO stop" (as a noun phrase), make
literal sense.

Nope, I don't have to. I will just point out that my camera
allows me the choice to change shutter and exposure in half and
third stop steps, each step being thus very different from a stop.

How does your nomenclature handle steps that are smaller than
steps? Does 1/3rd step steps sound logical, useful or (and
that's what nomenclature is needed for) unambigous?

If you knew the answer all along, why didn't you just give it at an
appropriate time? :- )

Because you wanted to measure, nothing about roughly ...

"... measure or determine the number of exposure steps [zones] ...". There's
nothing in my question or the subsequent discussion that says "number" has
to be more precise than one significant digit. You're arguing against your
own unfounded assumptions and prejudices.

As in ... "your monitor has quite exactly 8 stops range"? Yes, I took your
word somehow, won't happen again.

And how comes you want ONE significant digit and just dividing
the range of 0-255 in 8 equilong steps doesn't do it for you?
*Obviously* you wanted more ...

--- and my point still stands: will your image in it's later
representation
have 8 stops of range? Can your prints even deliver 8 ranges?

The image on the monitor is the final representation.

So please take your camera and measure 0,0,0 and 255,255,255.
What's aperture, exposure time, ISO setting? Roughly is good
enough for a basic check.

So what is the difference between 0 and 255 in the *final*
represenation of the image?

Eight steps.

And what size are these steps?

-Wolfgang

Wolfgang Weisselberg wrote:
Wilba wrote:
Wolfgang Weisselberg wrote:

It [using a camera to measure exposure values from a monitor]
works well enough.
It also shows the monitor doesn't produce 8 an stop range between
0,0,0 and 255,255,255. Yes, calibrated monitor.
Wheee --- out of the window goes your assumption.
As I said, your calculations and musings depend too much on
unwarranted, unchecked assumptions.

Not my assumptions. Not my calculations. Not relevant to the topic. So your
gripe is with Koren. No worries. I'll leave it with you and him (see
http://www.normankoren.com/zonesystem.html).

To argue your position, you'd have to explain how expressions like
"stop down the shutter" (as an action), or "ISO stop" (as a noun
phrase), make literal sense.

Nope, I don't have to. I will just point out that my camera
allows me the choice to change shutter and exposure in half and
third stop steps, each step being thus very different from a stop.

LOL. Nice try! (Irony.)

How does your nomenclature handle steps that are smaller than
steps? Does 1/3rd step steps sound logical, useful or (and
that's what nomenclature is needed for) unambigous?

If precision was required, I'd use the same term for that thing in that
context as does my camera's menu system - "exposure level increments" -
unless a more apt generic term was accepted by consensus.

Returning to the subject of this fibre, it remains for you to prove that
"stop" is right and "step" is wrong as a shorthand for a power-of-2 exposure
value step not specific to variation by aperture size.

Wilba wrote:
Wolfgang Weisselberg wrote:
Wilba wrote:
Wolfgang Weisselberg wrote:

It [using a camera to measure exposure values from a monitor]
works well enough.
It also shows the monitor doesn't produce 8 an stop range between
0,0,0 and 255,255,255. Yes, calibrated monitor.
Wheee --- out of the window goes your assumption.
As I said, your calculations and musings depend too much on
unwarranted, unchecked assumptions.

Not my assumptions.

I did ask you. You asserted that your monitor had 8 stops ...
based on something you read somewhere.

Not my calculations.

Right, you copied them.

Not relevant to the topic.

Your assumtions and the calculations you pulled up are "not
relevant to the topic"? Well, well, well.

So your gripe is with Koren.

Nope. My gripe is with you, not with someone you quoted
without understanding.

To argue your position, you'd have to explain how expressions like
"stop down the shutter" (as an action), or "ISO stop" (as a noun
phrase), make literal sense.

Nope, I don't have to. I will just point out that my camera
allows me the choice to change shutter and exposure in half and
third stop steps, each step being thus very different from a stop.

LOL. Nice try! (Irony.)

Ah, you have no answer.

How does your nomenclature handle steps that are smaller than
steps? Does 1/3rd step steps sound logical, useful or (and
that's what nomenclature is needed for) unambigous?

If precision was required, I'd use the same term for that thing in that
context as does my camera's menu system - "exposure level increments" -
unless a more apt generic term was accepted by consensus.

You're perfectly right, "exposure level increments ... 1/3rd
stop" is what my camera calls it. Inclusive calling it st*o*p.
Just like your camera. :-) Want a screen shot?.

You just replaced the wrong 'step'! Duh, but I admit, it's an
easy mistake. Another reason to use stops.

Returning to the subject of this fibre,

Yes, have you measured the contrast range of yon screen yet?
So what's the answer, how did you measure it and under which
conditions (daylight and incandescent light and full darkness
would be a start) did you do it?

it remains for you to prove that
"stop" is right and "step" is wrong as a shorthand for a power-of-2 exposure
value step not specific to variation by aperture size.

I'm not saying that step is absolutely wrong, but at least uncommon
useage for what you use it for and prone to misunderstandings.
My monitor has a range of as many steps as the graphic adapter
outputs (it's an analog device, see?) and a certain range of stops
that mostly depend on how black black is (see reflected light).

-Wolfgang

Wolfgang Weisselberg wrote:
Wilba wrote:

Nope. My gripe is with you, not with someone you quoted
without understanding.

Everything you've said is attacking your own fantasy, created by twisting
the question and my answers to suit your goals.

(For the last time) it's nothing to do with how the eye sees the scene or
the image. It's only about the levels in the image data (as shown, for
instance, by the Info window in Photoshop).

Any claim that you subsequently make that I _intended_ a different question
is hereby pre-invalidated. :- )

have you measured the contrast range of yon screen yet?

Yon screen in front of me? Yes I have, and the result was interesting, but
irrelevant as ever.

it remains for you to prove that "stop" is right and "step" is wrong
as a shorthand for a power-of-2 exposure value step not specific
to variation by aperture size.

I'm not saying that step is absolutely wrong, but at least uncommon
useage for what you use it for and prone to misunderstandings.

Right, so we agree that it's wrong to make assertions like, "it's not
st*e*ps, it's st*o*ps". Thanks.

Thanks for helping me make sense of this for myself. It has been fun. I will
only reply to you if you say something relevant about the actual question.

Wilba wrote:
Wolfgang Weisselberg wrote:
Wilba wrote:

Nope. My gripe is with you, not with someone you quoted
without understanding.

Everything you've said is attacking your own fantasy, created by twisting
the question and my answers to suit your goals.

(For the last time) it's nothing to do with how the eye sees the scene or
the image. It's only about the levels in the image data (as shown, for
instance, by the Info window in Photoshop).

I apologise. I was mistakenly thinking you were talking
about photography or visual arts. You know, the stuff you
need to use your eyes for.

What you _wanted_ all along but never said was:
| If I *randomly*[1] decide that a field of RGB-data *has* 8 stops
| of luminance contrast between 0,0,0 amd 255,255,255 and if said
| field was gamma-2.2 8-bit encoded, what would *roughly* be the
| step size for one stop of difference?
|
| [1] on no factual basis, just based on something I read and didn't
| test nor understand for monitors.

Any claim that you subsequently make that I _intended_ a different question
is hereby pre-invalidated. :- )

What you _wrote_ was something completely different:
| If I'm looking at an image in something like Photoshop (in which I can
| easily read the RGB levels for any pixel), how can I measure or determine
| the number of exposure steps between two pixels or areas in the image?
(see Message-ID )

- without stating that you have decided on 8 stops
- without talking about 'roughly' --- misleadingly giving the
opposite idea you needed quite exact answers
- without making clear that your "exposure steps" were not
meant as 1/3 or 1/2 stops ...
- while misleadingly claiming you were looking at "an image"
--- it's not an image, it's a field of data to you, and you
don't look at it, you measure RGB levels
-

Thus you may have not intended a different question, but you sure
*wrote* a completely different question. Hence I must question
your question-writing ability. Questions?

have you measured the contrast range of yon screen yet?

Yon screen in front of me? Yes I have, and the result was interesting, but
irrelevant as ever.

Exactly as I thought, it's not even within one stop of 8 stops,
for else you'd given me the rasberry and danced "it's 8.2 stops,
tptptptptp"!


it remains for you to prove that "stop" is right and "step" is wrong
as a shorthand for a power-of-2 exposure value step not specific
to variation by aperture size.

I'm not saying that step is absolutely wrong, but at least uncommon
useage for what you use it for and prone to misunderstandings.

Right, so we agree that it's wrong to make assertions like, "it's not
st*e*ps, it's st*o*ps". Thanks.

So we agree that st*e*ps is the wrong word to use. Thanks.

-Wolfgang