Of course ISO is an exposure variable - when you are shooting digital

[Andre Affleck]

Josh152 wrote:

Great Bustard wrote:

gollywop wrote:

jrtrent wrote:

tomtom50 wrote:

Fir film cameras exposure is aperture and shutter speed, because those are the dials you twist picture optimally bright balancing what you need for other attributes like dof, sharpness, and blur. Adjusting your camera to get the right brightness balancing the other attributes needed a good strong word because that was an important part of taking good pictures.

Now with digital camera we have three settings to get the right brightness balancing the other attributes. We know have new attributes in the mix, DR, detail, and noise

I like your thinking, but I don't really see much difference between digital and film with these three variables. ISO was still something that was chosen, and for those who used cut film or multiple camera bodies, there was some flexibility from shot to shot--though not as easily as can now be done with digital!

This blurb reflects my use of exposure and ISO:

Exposure determines how much light gets to the film. All still cameras have two fundamental controls for this: lens aperture and shutter speed. The combination of the two is the exposure value, or EV used for exposure. Film speed (discussed later) determines the quantity of light that will properly expose the film. The combination of film speed and the brightness of the scene determine an EV that can be translated into specific combinations of aperture and shutter speed to capture the proper quantity of light. http://johnlind.tripod.com/science/scienceexposure.html

Good usage is usage that successfully communicates the relevant information, and becomes widespread. Technology changes and the words meanings change as well. That's why we dial phone numbers on phones that have no dials.

Good point. And a concept of exposure that includes three variables instead of two makes good sense to a lot of picture takers, some of whom have become quite famous and even written books using this idea. The "exposure triangle" has helped several people I know to get the results they want a much higher percentage of the time.

Yes, but they could have been helped just as well with a "brightness triangle" and come away with a better and more accurate idea of what they were doing.

Thing is, "brightness triangle" doesn't sound cool like "exposure triangle". I mean, would you rather say you're the trash man or say you're a sanitary engineer? ;-)

I was thinking the same thing. At some point "exposure" became kind of a status word. People who self identify as Photographers like to talk about a photos "exposure" because it makes them sound and more importantly feel more technical and savvy than their non photographer friends who talk about how a photo is too bright or too dark.

I think those of us who believe this are subconsciously self-reflecting. GB has even gone on record saying he enjoys watching the technically challenged squirm out of discussions. Are you sure it is not us who are trying to feel more important with this "entertainment"?

Look, the misuse of the term by these poor saps has nothing to do with sounding important. It is merely that fact that traditional photographers of much more pragmatic than sensor designers. Simple as that, nothing more. When they set exposure they consider all three so they just call it exposure. So? There is nothing more to be gained by pro photographers by asking them to do any different. Reducing noise by 8% doesn't sell them more photos. Got nothing to do with feeling important.

So lets just round them up in a public arena and persecute their ignorance for our measly entertainment. Oooo, can I get front row? Maybe GB can sell the screen play to the producers of Hunger Games III.

 

[tomtom50]

hjulenissen wrote:

tomtom50 wrote:

Language is democratic. The usage that is widely adopted in the one that wins.

That is why we still dial a phone number, instead of keying or tapping or whatever.

In that case Mandarin wins?

http://listverse.com/2008/06/26/top-10-most-spoken-languages-in-the-world/

I don't believe that language works as a homogenous majority vote. Rather, there are "islands" of people who use words and language in a certain way. Phycisists and engineers, for instance. And enthusiast photographers.

If 9/10 compact camera users talk about "exposure" in a certain way, this may or may not affect the system camera users who spends a lot of time learning their cameras.

-h

I agree with you on your latter points. Note I did not say anything about single votes.

Chinese develops democratically within its speakers. Psychological jargon develops more or less democratically within that community, etc.

 

[bobn2]

tomtom50 wrote:

Josh152 wrote:

Great Bustard wrote:

gollywop wrote:

jrtrent wrote:

tomtom50 wrote:

Fir film cameras exposure is aperture and shutter speed, because those are the dials you twist picture optimally bright balancing what you need for other attributes like dof, sharpness, and blur. Adjusting your camera to get the right brightness balancing the other attributes needed a good strong word because that was an important part of taking good pictures.

Now with digital camera we have three settings to get the right brightness balancing the other attributes. We know have new attributes in the mix, DR, detail, and noise

I like your thinking, but I don't really see much difference between digital and film with these three variables. ISO was still something that was chosen, and for those who used cut film or multiple camera bodies, there was some flexibility from shot to shot--though not as easily as can now be done with digital!

This blurb reflects my use of exposure and ISO:

Exposure determines how much light gets to the film. All still cameras have two fundamental controls for this: lens aperture and shutter speed. The combination of the two is the exposure value, or EV used for exposure. Film speed (discussed later) determines the quantity of light that will properly expose the film. The combination of film speed and the brightness of the scene determine an EV that can be translated into specific combinations of aperture and shutter speed to capture the proper quantity of light. http://johnlind.tripod.com/science/scienceexposure.html

Good usage is usage that successfully communicates the relevant information, and becomes widespread. Technology changes and the words meanings change as well. That's why we dial phone numbers on phones that have no dials.

Good point. And a concept of exposure that includes three variables instead of two makes good sense to a lot of picture takers, some of whom have become quite famous and even written books using this idea. The "exposure triangle" has helped several people I know to get the results they want a much higher percentage of the time.

Yes, but they could have been helped just as well with a "brightness triangle" and come away with a better and more accurate idea of what they were doing.

Thing is, "brightness triangle" doesn't sound cool like "exposure triangle". I mean, would you rather say you're the trash man or say you're a sanitary engineer? ;-)

I was thinking the same thing. At some point "exposure" became kind of a status word. People who self identify as Photographers like to talk about a photos "exposure" because it makes them sound and more importantly feel more technical and savvy than their non photographer friends who talk about how a photo is too bright or too dark.

Refusing to let a nice word like exposure evolve because one doesn't like the meaning of words changing, and instead minting new words with slightly different meanings happens, but not as often as schoolmarms would wish.

Language is democratic. The usage that is widely adopted in the one that wins.

That is such a rediculous (that seems to be the spelling that's winning, so it must be right) argument innit . Alot of photography is a technical/engineering (not to say the technically ignorant can't take totally sick photos) and science and engineering is based on formalised definitions. One of those, that underpins the whole of photography, is 'exposure'. Let the meaning of that become blurred and it becomes impossible to discuss sensibly the technical side of the subject (as these debates actually show very graphically). For instance, if 'exposure' doesn't mean what 'exposure' means, then 'ISO' doesn't mean anything at all. So, how do we explain to people what ISO is and does without using the word 'exposure'. We just have to substitute another word or phrase. But the ISO standards use the word 'exposure' so then you have to explain that when you said 'light density times time' it meant what 'exposure' meant in the ISO standards. And in fact your whole 'language is democratic' ida is a phallusy. 'Exposure' is not a 'widely adopted' term, it's a niche term that a very particular community uses, of which more later.

That is why we still dial a phone number, instead of keying or tapping or whatever.

People are used to think of exposure as getting the right brightness, and aperture & shutter speed & ISO as the things you adjust to get their.

People trying to set their cameras could care less about equations developed that were applicable to film, or what Wikipedia says in 2013.

Which is another fallacy. Obviously they do care, otherwise they wouldn't be using such high-falutin language as 'exposure'. In these discussions, someone said we had to define 'exposure' to include ISO because otherwise a soccer mom getting her prints at Costco wouldn't understand what someone meant by 'her prints were overexposed'. LOL. A soccer mom would quite reasonably think of her prints as being too bright or too dark. The only reason to call them 'overexposed' is because you're pretentious enough to use faux technical jargon to pose as being an expert. Then you get it wrong. That's what hurts these people, being busted.

Imagine you are teaching photography. Not photograph's technology, photography.

1. You set exposure by adjusting f-stop, aperture, and ISO to get the right brightness. Each of these affects your picture differently, so we are going to learn how to get the right exposure and the best picture by best balancing these settings.

2. You set exposure by adjusting f-stop and aperture to adjust the amount of light hitting the sensor. Each of these affects your picture differently. Also you set the gain on the sensor so your file has the right brightness range. This affects your picture as well. We will learn how to aperture, shutter speed, and ISO adjustments affect your picture so you can choose the right exposure and amplification setting.

The latter delves into the technology more than is needed to take the best picture, and so is not a good word (as defined for film) to use with digital cameras. So we can expand the meaning of the word a bit or drop it entirely for reasons only techies understand?

Silly example because what you could have said, if you weren't trying to impress by (mis) using the word 'exposure' is:

1. You set the brightness by adjusting f-stop, aperture, and ISO. Each of these affects your picture differently, so we are going to learn how to get the brightness you want and the best picture by balancing these settings.

Simpler, less confusing and to the point. Of course it misses out all the twaddle about 'exposure' and getting the 'right' exposure (whatever that is), and just uses the word 'brightness' which you had anyway. The word 'exposure' was completely redundant.

 

[robert1955]

Gerry Winterbourne wrote:

By any rational use of English exposure time, as opposed to exposure duration, should mean not how long the exposure was but when it was taken. But, of course, this is pedantry gone mad.

Yep it is. That i incorrect usage. But two wrongs do noy make one right

Everyone knows that exposure time can have different meanings depending on context. After all, that's true of a lot of expressions.

Indeed, it's true of exposure too.

Here you commit a rhetorical trick. What you're saying is "A is not B", therefore C is not D"

There's nothing wrong with the definition you quote here and it's fine in the context for which it is intended.

But is still the defintion on which the system is built, so it is not a matter of preference

But, like exposure time, exposure has other meanings depending on context. It isn't an error, as you suggest, to use a term in a different context from the one you happen to prefer.

The context is how camera's work. The use of the idea that exposure does not contain the so-called ISO setting, means that you can think of other ways to set the camera to reach your desired results. You may not agree with that, but then should write about that, and not play a language game.

The logic failure in my title refers to the idea of thinking that exposure can only have one meaning while defining it by reference to a term that can have multiple meanings - if all terms must have just one meaning the definition itself is wrong; or multiple meanings are fine.

I see no logic at all in that last paragraph.

 

[Allan Olesen]

bobn2 wrote:
The key is in the meaning of the word 'exposure', which is the same whether you're talking photometric or radiometric.

Which was exactly my point.

 

[bobn2]

Allan Olesen wrote:

bobn2 wrote:

The key is in the meaning of the word 'exposure', which is the same whether you're talking photometric or radiometric.

Which was exactly my point.

Yes, I wasn't disagreeing, just reinforcing.

 

[Allan Olesen]

David Hull wrote:

There is also the element of time and radiation intensity.

Just as there is in photographic exposure. What are you trying to say?

My point still stands:

When any person or medium is exposed to something - light, radiation or something else - you can't change the exposure afterwards, and the sensitivity of the person/medium does not change the exposure.

And yet, a lot of people argue that you can do exactly that with photographic exposure: Change the exposure afterwards or by changing properties of the photographic medium. This clearly shows that those people haven't thought about what the word "exposure" basically means in a non-photographic context.

 

[bobn2]

Andre Affleck wrote:

I think those of us who believe this are subconsciously self-reflecting. GB has even gone on record saying he enjoys watching the technically challenged squirm out of discussions. Are you sure it is not us who are trying to feel more important with this "entertainment"?

Look, the misuse of the term by these poor saps has nothing to do with sounding important. It is merely that fact that traditional photographers of much more pragmatic than sensor designers. Simple as that, nothing more. When they set exposure they consider all three so they just call it exposure. So? There is nothing more to be gained by pro photographers by asking them to do any different. Reducing noise by 8% doesn't sell them more photos. Got nothing to do with feeling important.

I disagree. I think the average person with a camera, who didn't consider themselves a photographer would probably never sue the word 'exposure' or 'under exposed' or 'over exposed'. They would talk about the picture being 'too dark' or 'too light'. 'Exposure' is a jargon word, and people adopt jargon either because a precise vocabulary is required for precise communication or to illustrate membership of an 'expert' fraternity. I can't see why else they would do it, because calling 'brightness' 'exposure' just makes communication more difficult. You wouldn't do it for reasons of pragmatism, if you were pragmatic, you'd use the existing word that allowed you to communicate most widely.

So lets just round them up in a public arena and persecute their ignorance for our measly entertainment. Oooo, can I get front row? Maybe GB can sell the screen play to the producers of Hunger Games III.

They throw themselves to the lions, often very aggressively. People who are just wrong don't get treated harshly. Even people who insist on remaining wrong aren't. The ones who are are the ones who insist, in the face of every bit of evidence and argument that they are right, the others are wrong and will stop at no insult or defamation when they run out of evidence and argument. They're fair game.

 

[Great Bustard]

tkbslc wrote:

Great Bustard wrote:

tkbslc wrote:

Great Bustard wrote:

tkbslc wrote:

Great Bustard wrote:

The camera controls that affect exposure are the aperture, shutter speed, and flash power -- period. Yes, the ISO setting indirectly affects these settings depending on the AE (Auto Exposure) mode you are using, but the ISO setting itself is not an element of exposure. In short, do not confuse correlation with causation (for example, thinking that the calendar is what causes the seasons).

I don't think flash power directly affects exposure anymore than the time of day or shooting location does.

Well, you'd be wrong. Exposure is determined by three, and only three, parameters:

• Scene Luminance
• t-stop (usually closely approximated by the f-ratio)
• Shutter Speed

The flash power affects the scene luminance, and therefore affects the exposure.

Many things affect scene luminance, even down to the color of the subject. If I put up a shade or use a reflector, I change luminance. If I wait an hour for the sun to change position, I've affected scene luminance. Singling out flash makes no sense.

Who's "singling out flash"? As I said, scene luminance is one of the three elements of exposure, and the camera's flash will affect that particular element.

You did. I'll requote you from a couple posts up:

"The camera controls that affect exposure are the aperture, shutter speed, and flash power -- period"

To which I replied:

"I don't think flash power directly affects exposure anymore than the time of day or shooting location does."

Now you are saying you just meant scene luminance, which sounds like you are agreeing with what I originally said.

Tell me if you understand the difference in the following two statements:

• Exposure is determined entirely by the scene luminance, t-stop (usually the f-ratio is close enough), and the shutter speed.
• The camera controls that affect exposure are the aperture, shutter speed, and flash power -- period.

Can you tell the difference? Myself, I'm thinking the difference between the two statements is obvious enough that further clarification is unnecessary, but let me know, and I'll be happy to spell it out in more detail.

The flash power is just the amount of light in the scene, the exposure controls how much of it makes it to the image.

If we keep the aperture and shutter speed constant, then more flash power means a greater exposure, less flash power means a lower exposure.

As does shooting at night vs during the day. Is the Sun part of the exposure settings? Is time of day or the weather?

The scene luminance is one of three elements to exposure.

If you'd said that originally, I probably wouldn't be arguing with you now.

There are lots of things I didn't say that are true that I did not say. Are you saying that every time I talk about the camera controls that affect exposure that I need to first define exposure each and every time?

I feel like if you are going to call flash power part of the exposure than we should also call "how far I open my drapes in the living room during little Sally's b-day party" part of the exposure.

Well, best of luck to you, then.

If I open my drapes, does that not affect scene luminance?

Yes (well, assuming it's not dark outside). Did I say or imply otherwise?

Just above you said "best of luck to you" which I interpreted as a dismissal of my statement as incorrect.

I said "best of luck" in that you misinterpreted what I felt to be an unambiguously simple and clear statement -- that flash power was one of the three camera controls that directly affects exposure.

 

[David Hull]

Allan Olesen wrote:

David Hull wrote:

There is also the element of time and radiation intensity.

Just as there is in photographic exposure. What are you trying to say?

My point still stands:

When any person or medium is exposed to something - light, radiation or something else - you can't change the exposure afterwards, and the sensitivity of the person/medium does not change the exposure.

And yet, a lot of people argue that you can do exactly that with photographic exposure: Change the exposure afterwards or by changing properties of the photographic medium. This clearly shows that those people haven't thought about what the word "exposure" basically means in a non-photographic context.

I completely agree, perhaps I missed your point (wouldn't be hard, there are so damn many of them flying around here ;-) )

 

[bobn2]

Great Bustard wrote:

I said "best of luck" in that you misinterpreted what I felt to be an unambiguously simple and clear statement -- that flash power was one of the three camera controls that directly affects exposure.

To be fair to you, you use cameras with no built-in flash and don't own a flashgun (or didn't until recently) - not something you'd think of. And in point of fact, one of the advantages of 'understanding exposure' (over blind ISO worship) is that you can get better results in difficult available light.

 

[toomanycanons]

The thread subject that just keeps on going.

No, I didn't read the previous 393 replies spread across three threads. Here's what I have to say:

Since my Nikon DSLRs are clean to ISO 1600 (or more) it's a non-issue me changing ISO from 100 to at least 800 or even 1600. The shutter speed doubles every time I up the ISO (100-200-400-800 etc) and if I think my shutter is going to be too low, I just up the ISO.

Is that even the topic that's being discussed here?

 

[tomtom50]

Basically, yes.

 

[toomanycanons]

tomtom50 wrote:

Basically, yes.

Maybe you've read the entire three threads. What the heck is taking so long to discuss? Seems simple to me. BTW, I'm not losing any sleep over this. I have my Fn buttons programmed to ISO and change the ISO settings as needed. I lead such a simple life!

 

[tomtom50]

Loading…

www.luminous-landscape.com

Just published by Michael Reichmann, author of many books & videos on photography and video, reviewing the new Olympus E-M1.

He is a very good photographer, and very technically astute:

Loading…

www.luminous-landscape.com

"Another thing that Oly has done right is that it allows ISO to be used as the third exposure variable. In other words, you can go to Manual mode, set the shutter speed and the aperture that you need, and then let the camera automatically ride the ISO so that a proper exposure is achieved. And to put icing on the cake, one of the custom settings allows you to set which shooting modes auto ISO will work in. Now, that's customizibility!"

This is how people talk because it conveys the meaning. I know what he means. Everyone arguing knows what he means. Some say he is "wrong".

When someone uses a word and his meaning is widely understood - is that usage going to go away because of schoolmarms pointing to old meanings?

Go ahead and yell, the meaning has changed whether you like it or not. Write Reichmann and tell him how wrong he and see what he has to say.

 

[toomanycanons]

tomtom50 wrote:

http://www.luminous-landscape.com/r...om_d_e_m1_rolling_field_report.shtml#saturday

Just published by Michael Reichmann, author of many books & videos on photography and video, reviewing the new Olympus E-M1.

He is a very good photographer, and very technically astute:

http://www.luminous-landscape.com/r...om_d_e_m1_rolling_field_report.shtml#saturday

"Another thing that Oly has done right is that it allows ISO to be used as the third exposure variable. In other words, you can go to Manual mode, set the shutter speed and the aperture that you need, and then let the camera automatically ride the ISO so that a proper exposure is achieved. And to put icing on the cake, one of the custom settings allows you to set which shooting modes auto ISO will work in. Now, that's customizibility!"

This is how people talk because it conveys the meaning. I know what he means. Everyone arguing knows what he means. Some say he is "wrong".

When someone uses a word and his meaning is widely understood - is that usage going to go away because of schoolmarms pointing to old meanings?

Go ahead and yell, the meaning has changed whether you like it or not. Write Reichmann and tell him how wrong he and see what he has to say.

I forgot to say I usually shoot on A at f/6.3. In that mode I want to keep my shutter up past, I dunno, 1/40, sometimes 1/80, sometimes 1/120. I rarely shoot on M but if I am, I already have my S and A dialed in to what I want at whatever ISO I've chosen.

I just checked both my Nikon DSLRs and, indeed, I can leave the S and A at some designated number, on M, and dial my exposure up or down using my Fn button. Have to try that sometime.

 

[gollywop]

EinsteinsGhost wrote:

gollywop wrote:

EinsteinsGhost wrote:

gollywop wrote:

EinsteinsGhost wrote:

Allan Olesen wrote:

tomtom50 wrote:

The core thing we are doing (adjusting camera settings to get the right brightness balancing other attributes) hasn't changed, so neither should the word.

You hit the nail on the head here. But probably not as you intended.

I think a lot of people are mislead to think that exposure means "the act of getting the desired brightness". And those people will reach the incorrect conclusion that you did.

But exposure never had that meaning. And consequently your logic fails.

Exposure simply means that a sensor or film is exposed to light. Anything else you relate to the process of getting the desired brightness is not exposure.

By the definition being promoted in these re-created threads, exposure doesn't really need a film or sensor, or any kind of sensitometry.

You continue to be in error. Check out, for example,

http://en.wikipedia.org/wiki/Exposure_(photography)

where it says

exposure is the amount of light allowed to fall on each area unit of a photographic medium (photographic film or image sensor) during the process of taking a photograph. Exposure is measured in lux seconds, and can be computed from exposure value (EV) and scene luminance in a specified region.

The medium is always assumed; what is in question is which factors are in play (and which are not). That question is answered directly with the part that says exposure is defined as:

Hv = Ev .t

where

• Hv is the luminous exposure (usually in lux seconds)
• Ev is the image-plane illuminance (usually in lux)
• t is the exposure time (in seconds)

What is mentioned there are the factors that are in play.

1-Why do you think it mentions a photographic medium?

Because it explicitly mentions a photographic medium.

The question is: Why?

2-What do you think the exposure time relates to? And is it completely independent of the characteristics of photographic medium?

Gee, that's a tough one. When you change SS does your sensor change? When you change cameras to one with a different sensor, does the 1/100s SS change duration? I don't know; I really find it difficult to answer these questions. But perhaps you can, and then you can answer your own question.

The question was: What do you think the exposure time relates to?

No it wasn't the question; there was an and to it. But, in answer to your reframed question, it relates to the time the shutter is open. I guess there are other interpretations for that terminology, but only an idiot would consider them in this context.



--
gollywop

 

[gollywop]

David Hull wrote:

Allan Olesen wrote:

David Hull wrote:

There is also the element of time and radiation intensity.

Just as there is in photographic exposure. What are you trying to say?

My point still stands:

When any person or medium is exposed to something - light, radiation or something else - you can't change the exposure afterwards, and the sensitivity of the person/medium does not change the exposure.

And yet, a lot of people argue that you can do exactly that with photographic exposure: Change the exposure afterwards or by changing properties of the photographic medium. This clearly shows that those people haven't thought about what the word "exposure" basically means in a non-photographic context.

I completely agree, perhaps I missed your point (wouldn't be hard, there are so damn many of them flying around here ;-) )

Yes, I missed his point too. It was encased in too much clap-trap. But I agree with his sentiment, once made clear.



--
gollywop

 

[tomtom50]

gollywop wrote:

David Hull wrote:

Allan Olesen wrote:

David Hull wrote:

There is also the element of time and radiation intensity.

Just as there is in photographic exposure. What are you trying to say?

My point still stands:

When any person or medium is exposed to something - light, radiation or something else - you can't change the exposure afterwards, and the sensitivity of the person/medium does not change the exposure.

And yet, a lot of people argue that you can do exactly that with photographic exposure: Change the exposure afterwards or by changing properties of the photographic medium. This clearly shows that those people haven't thought about what the word "exposure" basically means in a non-photographic context.

I completely agree, perhaps I missed your point (wouldn't be hard, there are so damn many of them flying around here ;-) )

Yes, I missed his point too. It was encased in too much clap-trap. But I agree with his sentiment, once made clear.

 

[gollywop]

Gerry Winterbourne wrote:

gollywop wrote:

Gerry wrote:

gollywop wrote:

You continue to be in error.

exposure is the amount of light allowed to fall on each area unit of a photographic medium (photographic film or image sensor) during the process of taking a photograph. Exposure is measured in lux seconds, and can be computed from exposure value (EV) and scene luminance in a specified region.

The medium is always assumed; what is in question is which factors are in play (and which are not). That question is answered directly with the part that says exposure is defined as:

Hv = Ev .t

where

• Hv is the luminous exposure (usually in lux seconds)
• Ev is the image-plane illuminance (usually in lux)
• t is the exposure time (in seconds)

By any rf defining the meaning of a term in one context can alter - or wipe out ational use of English exposure time, as opposed to exposure duration, should mean not how long the exposure was but when it was taken. But, of course, this is pedantry gone mad. Everyone knows that exposure time can have different meanings depending on context. After all, that's true of a lot of expressions.

Indeed, it's true of exposure too. There's nothing wrong with the definition you quote here and it's fine in the context for which it is intended. But, like exposure time, exposure has other meanings depending on context. It isn't an error, as you suggest, to use a term in a different context from the one you happen to prefer.

The logic failure in my title refers to the idea of thinking that exposure can only have one meaning while defining it by reference to a term that can have multiple meanings - if all terms must have just one meaning the definition itself is wrong; or multiple meanings are fine.

Pedantry of the most errant kind.

The time is stated to be given in seconds. Such a criteria is completely meaningless relative to time of day since no origin is given, and even if one were, the resulting figure would have no immediate meaning to anyone.

You've completely missed the point, which is that "exposure time" has at least two meanings (1) time of occurrence - the general English meaning - and (2) duration of exposure - the special photographic meaning assigned in the definition you quote.

As you say, the unit of measurement renders one of these meanings irrelevant in the context. Indeed, it's the context that points to which meaning of the two is intended.

What you and the others trying to pin down "exposure" to only the meaning defined above is that, just like "exposure time" "exposure" has more than one meaning. Moreover, as with "exposure time", which meaning is intended is clear from the context.

No, I rather think you're missing the point. Exposure time is indeed crystal clear from context, and only an abject fool would be mislead into another meaning. The term exposure, however, when used to include ISO can be, and typically is, very misleading and readily leads to misunderstandings.

When someone refers to an image as overexposed that is, in fact, properly exposed but over brightened, the term has been used so as to mislead. And the misled person has been deprived of understanding how he/she could have taken a better image because of it. When someone thinks that, by increasing ISO, he/she is increasing exposure rather than brightening, that person has been misled into producing an image with more noise than need be because he/she has been misled by the terminology and the notions that a correct understanding might have brought about.

The term "exposure time" is patently clear and, in any event, leads to possible ambiguities that cause no harm. The same cannot be said for a misuse of the term "exposure." We're talking small change vs. big bucks in the potential harm arising from the "misuse" of these two concepts. In one case, misunderstanding has trivial consequences; in the other case misunderstanding has quite significant consequences. To try to say that the acceptance of one should imply the acceptance of the other is like saying that robbery is a crime and murder is a crime, so they should be treated the same because they are both crimes.

--
gollywop