Exposure understanding and definition

[beatboxa]

I think this understanding of ISO as one of the three values affecting exposure, while not strictly correct, is deeply embedded in minds of generations of photographers. Should the photographic community try to change it? Why and how?

No.

It's also not deeply embedded in the minds of generations of photographers.

It's deeply embedded in the minds of film photographers. It was wrong then too, but it stuck because ISO was fixed for a roll and the development process was complicated.

But neither of these is true in digital photography.

Recently, there was this recent boom of wannabe digital photographers, who somehow missed the memo that ISO is not sensor sensitivity, that it is now a variable per shot, and that it is exposure compensation--not exposure--for a given output brightness.

Compensation, by the way, meaning "something else that makes up for something lacking." Something can not simultaneously be both exposure and exposure compensation as Zeiss implied. This concept makes no sense.

These budding photographers might be stubborn and ignorant, but don't confuse what I'll call "mental inertia" for mental depth. It can not be deeply embedded into their photographers' minds because their knowledge on the subject isn't deep to begin with. The concepts were so complicated to them that the only way they could learn anything was by putting "what to do" into the form of a shape. And "what to do" is distinct from "how things work."

We're now seeing significant amounts of decline in these type of photographers. I say: good riddance.

And no, we shouldn't cater technical language to suit them. We similarly shouldn't say that light switches are a part of electricity just because children think that's how lights work.

 

[beatboxa]

...

It would be a pretty rare shot that required Speed and Aperture to be fixed before ISO is thought about, I'm thinking.

Most of my shooting is that way. ISO gets set last, usually by the camera using Auto-ISO.

Exposure is what is affecting the quality, not the ISO setting. Now, of course, if one is foolish enough to needlessly set ISO manually first, to a value above base, that decision can put a limit on exposure, and hence on quality.

Ditto for me.

Same.

The only time I do the opposite--and the only time I manually set an ISO--is when I have plenty of light, such as tripod-landscapes, studio, direct sunlight, etc. And in these cases, I always set the ISO to the lowest base ISO of the camera--usually 100.

In all other cases I can think of, I fix speed and aperture before ISO. I use auto-ISO, and I use EC to control the ISO, which would have the same effect as just changing the ISO myself (which I would still do last).

I said this in the past, but I generally use what I call "Exposure priority," not "ISO priority." The only time I use "ISO priority" is those rare cases I listed above when I have enough light and exposure is not the issue.

 

[kiwi2]

...

It would be a pretty rare shot that required Speed and Aperture to be fixed before ISO is thought about, I'm thinking.

Most of my shooting is that way. ISO gets set last, usually by the camera using Auto-ISO.

Exposure is what is affecting the quality, not the ISO setting. Now, of course, if one is foolish enough to needlessly set ISO manually first, to a value above base, that decision can put a limit on exposure, and hence on quality.

Gosh. How has anyone been able to take a decent digital photo over the last 20 years or so. It must of been dumb luck all this time. Good thing the photography world now has the likes of Lee Jay and yourself to set the unwashed masses straight.

(PS, in case you don't realize, I'm being sarcastic)

 

[Jerry R]

I think this understanding of ISO as one of the three values affecting exposure, while not strictly correct, is deeply embedded in minds of generations of photographers. Should the photographic community try to change it? Why and how?

No.

It's also not deeply embedded in the minds of generations of photographers.

It's deeply embedded in the minds of film photographers. It was wrong then too, but it stuck because ISO was fixed for a roll and the development process was complicated.

But neither of these is true in digital photography.

Recently, there was this recent boom of wannabe digital photographers, who somehow missed the memo that ISO is not sensor sensitivity, that it is now a variable per shot, and that it is exposure compensation--not exposure--for a given output brightness.

Compensation, by the way, meaning "something else that makes up for something lacking." Something can not simultaneously be both exposure and exposure compensation as Zeiss implied. This concept makes no sense.

These budding photographers might be stubborn and ignorant, but don't confuse what I'll call "mental inertia" for mental depth. It can not be deeply embedded into their photographers' minds because their knowledge on the subject isn't deep to begin with. The concepts were so complicated to them that the only way they could learn anything was by putting "what to do" into the form of a shape. And "what to do" is distinct from "how things work."

We're now seeing significant amounts of decline in these type of photographers. I say: good riddance.

And no, we shouldn't cater technical language to suit them. We similarly shouldn't say that light switches are a part of electricity just because children think that's how lights work.

I'm an old (literally) film photographer and chose film ISO depending on the exposure parameters (speed and f-stop) required for a particular set of pictures. I remember having a camera (Nikon or Canon) where I could change film if a faster or slower speed film (receptor) was required.

A few years back some of us set an exposure at 100 ISO (which was too low and produced a dark image). PP the image could be brought back to life similar to which would have been obtained if ISO 800 were used.

QED: The exposure is independent of ISO.

 

[beatboxa]

I think this understanding of ISO as one of the three values affecting exposure, while not strictly correct, is deeply embedded in minds of generations of photographers. Should the photographic community try to change it? Why and how?

No.

It's also not deeply embedded in the minds of generations of photographers.

It's deeply embedded in the minds of film photographers. It was wrong then too, but it stuck because ISO was fixed for a roll and the development process was complicated.

But neither of these is true in digital photography.

Recently, there was this recent boom of wannabe digital photographers, who somehow missed the memo that ISO is not sensor sensitivity, that it is now a variable per shot, and that it is exposure compensation--not exposure--for a given output brightness.

Compensation, by the way, meaning "something else that makes up for something lacking." Something can not simultaneously be both exposure and exposure compensation as Zeiss implied. This concept makes no sense.

These budding photographers might be stubborn and ignorant, but don't confuse what I'll call "mental inertia" for mental depth. It can not be deeply embedded into their photographers' minds because their knowledge on the subject isn't deep to begin with. The concepts were so complicated to them that the only way they could learn anything was by putting "what to do" into the form of a shape. And "what to do" is distinct from "how things work."

We're now seeing significant amounts of decline in these type of photographers. I say: good riddance.

And no, we shouldn't cater technical language to suit them. We similarly shouldn't say that light switches are a part of electricity just because children think that's how lights work.

I'm an old (literally) film photographer and chose film ISO depending on the exposure parameters (speed and f-stop) required for a particular set of pictures. I remember having a camera (Nikon or Canon) where I could change film if a faster or slower speed film (receptor) was required.

A few years back some of us set an exposure at 100 ISO (which was too low and produced a dark image). PP the image could be brought back to life similar to which would have been obtained if ISO 800 were used.

QED: The exposure is independent of ISO.

Yes, agree in almost all cases.

The exception to this rule in digital photography is when you have plenty of light and want to maximize dynamic range. In those cases, you set the ISO to the lowest base ISO, and then maximize the exposure based on how much you can expose for this ISO. This is one of (if not the only) case I can think of where exposure selection should be based on ISO.

The two are always independent variables, but one could effect the choice that the photographer or camera makes in selection of the other. And in digital photography, exposure is almost always the independent variable, while ISO will be a reaction to this.

By the way, here is a digital illustration of the same concept you are describing above:

• https://www.dpreview.com/forums/post/59889138

And here is how I try to explain these distinct ISO vs. exposure concepts to the beginners:

• https://www.dpreview.com/forums/post/60967081

 

[Tony10]

To me exposure compensation is more about evaluating the scene and adjusting the metered exposure within the confines of the ISO, I routinely shot in Norway during the winter and often had to set exp. comp. on my F2/F3 to the minus settings to factor in the snow which sometimes filled the frame. ISO was changed in extreme cases when lighting was insufficient for the desired exposure, it was then simply a case of increasing development, (and remembering to mark the film cassette.

Obviously when changing the ISO you had the choice of either doing so via the ISO setting or the exp. comp. dial but the latter was not recommended.

 

[Michael Fryd]

Use of the term, sensitivity, tends to reinforce the mistaken notion that ISO determines the sensitivity of the sensor; it's ability or efficiency to capture light. ISO does not determine sensitivity.

As far as I am aware, all the camera manufacturers refer to ISO as "ISO Sensitivity". So, presumably you would say that they have all misunderstood what ISO means and need to be re-educated!

Really, are you serious? The people who make cameras do not understand what ISO means?

The people who design and make cameras absolutely understand what ISO is, and what it means.

These are not the people who write user manuals and marketing materials. Their goal is to sell cameras, and instruct people in basic operation. What they write doesn't need to be 100% correct.

 

[TeddyD]

There are no "generations" behind "exposure triangle", it is a recent thing (appeared circa 2003...

Surely you are referring to the term, not the concept.

The concept is demonstrably wrong (absurd would be a better word). Nothing like it was ever discussed among my colleagues.

The phrase was: for normal density, given film is rated xxx, you need yy exposure (a pair of shutter speed and f-stop, for example). Film speed was never understood as a part of exposure. The concept was density triangle, not exposure triangle; same like now it is default manufacturer rendering lightness triangle, not exposure triangle.

Going back to film cameras some had the EV on the same wheel as ISO (ASA or DIN) and some models didn't have EV at all, like Canon AV1. So I understand perfectly where the original statement comes from..

Not sure I understand what original statement you are referring too.

This

..the Zeiss manager explained: "If a photographer is manually controlling shutter speed and aperture, then the only way they have of further affecting exposure is ISO. So they can use the ISO dial as exposure compensation, effectively."

As I understand it's the one and only original statement in this thread..

The analogy between high ISO grain in film and high ISO noise in digital is an easy one, but it is a lazy one and the wrong one.

Not entirely, You can't either do nothing usefull with RAW file if you don't process it first, same as with unprocessed film.

You can't do anything with an unprocessed JPEG too. Before conversion, it's not even RGB, and it's mosaicked.

That's pretty much fundamental for anything digital unless hexadecimal is your second language..

 

[Iliah Borg]

There are no "generations" behind "exposure triangle", it is a recent thing (appeared circa 2003...

Surely you are referring to the term, not the concept.

The concept is demonstrably wrong (absurd would be a better word). Nothing like it was ever discussed among my colleagues.

The phrase was: for normal density, given film is rated xxx, you need yy exposure (a pair of shutter speed and f-stop, for example). Film speed was never understood as a part of exposure. The concept was density triangle, not exposure triangle; same like now it is default manufacturer rendering lightness triangle, not exposure triangle.

Going back to film cameras some had the EV on the same wheel as ISO (ASA or DIN) and some models didn't have EV at all, like Canon AV1. So I understand perfectly where the original statement comes from..

Not sure I understand what original statement you are referring too.

This

..the Zeiss manager explained: "If a photographer is manually controlling shutter speed and aperture, then the only way they have of further affecting exposure is ISO. So they can use the ISO dial as exposure compensation, effectively."

As I understand it's the one and only original statement in this thread..

I think I also understand, but that doesn't make what he said accurate. Exposure compensation changes exposure; changing ISO by itself doesn't change the exposure and, again, by itself, can't be considered exposure compensation, effectively or otherwise.

The analogy between high ISO grain in film and high ISO noise in digital is an easy one, but it is a lazy one and the wrong one.

Not entirely, You can't either do nothing usefull with RAW file if you don't process it first, same as with unprocessed film.

You can't do anything with an unprocessed JPEG too. Before conversion, it's not even RGB, and it's mosaicked.

That's pretty much fundamental for anything digital unless hexadecimal is your second language..

Many image files / formats / format variants contain non-mosaicked RGB data

 

[Tom Axford]

Use of the term, sensitivity, tends to reinforce the mistaken notion that ISO determines the sensitivity of the sensor; it's ability or efficiency to capture light. ISO does not determine sensitivity.

As far as I am aware, all the camera manufacturers refer to ISO as "ISO Sensitivity". So, presumably you would say that they have all misunderstood what ISO means and need to be re-educated!

Really, are you serious? The people who make cameras do not understand what ISO means?

The people who design and make cameras absolutely understand what ISO is, and what it means.

These are not the people who write user manuals and marketing materials. Their goal is to sell cameras, and instruct people in basic operation. What they write doesn't need to be 100% correct.

So now you are asking us to believe that every camera manufacturer has, by coincidence, used the same incorrect and misleading terminology without any of the company's engineers picking up on it!

I'll stick with using the term "ISO sensitivity". It makes good sense and accords with the common English usage of "sensitivity" in other contexts.

The very first paragraph of the Wikipedia article on film speed says:

Film speed is the measure of a photographic film's sensitivity to light, determined by sensitometry and measured on various numerical scales, the most recent being the ISO system. A closely related ISO system is used to describe the relationship between exposure and output image lightness in digital cameras.

A film's sensitivity relates the exposure to the density of the final negative. A digital camera's sensitivity relates the exposure to the lightness of the final image. Exactly analogous!

 

[Bill Ferris]

Use of the term, sensitivity, tends to reinforce the mistaken notion that ISO determines the sensitivity of the sensor; it's ability or efficiency to capture light. ISO does not determine sensitivity.

As far as I am aware, all the camera manufacturers refer to ISO as "ISO Sensitivity". So, presumably you would say that they have all misunderstood what ISO means and need to be re-educated!

Really, are you serious? The people who make cameras do not understand what ISO means?

Just to clarify, are you stating that ISO does control a sensor's sensitivity to light and that, as ISO is increased, a sensor becomes more sensitive to light? It will capture more light during a shutter actuation than at the same settings but a lower ISO. Is that what you're saying?

With respect to camera manufacturers, I've seen the same as you in both printed manuals and official online content. I've seen it in their educational content written specifically for photographers. This brings to mind an old saying. I may be paraphrasing but it goes something like this, "Just because all the kids are doing it, doesn't make it any less wrong."

Why do camera manufacturers promote an erroneous understanding of what ISO is and how it's used? I don't know. Nor do I particularly care. As long as they keep designing, manufacturing and selling outstanding products, I'm a happy guy.

I also don't assume that some entry-level employee who creates content for the company website has any better technical understanding of how cameras work than a reasonably experienced and well-informed enthusiast photographer. I've seen it too many times: sales and marketing staff have a way with words but all too often don't truly know or understand the product.

We don't have control over what the manufacturers write. But we do have some influence on how technical topics are discussed and explained in online community forums. Why shouldn't we make the effort to find a way to convey information in a conversational manner that is both accurate and empowering? Afterall, the better a person understands how their camera works, the better able they'll be to take full advantage of its potential.

 

[Michael Fryd]

Use of the term, sensitivity, tends to reinforce the mistaken notion that ISO determines the sensitivity of the sensor; it's ability or efficiency to capture light. ISO does not determine sensitivity.

As far as I am aware, all the camera manufacturers refer to ISO as "ISO Sensitivity". So, presumably you would say that they have all misunderstood what ISO means and need to be re-educated!

Really, are you serious? The people who make cameras do not understand what ISO means?

The people who design and make cameras absolutely understand what ISO is, and what it means.

These are not the people who write user manuals and marketing materials. Their goal is to sell cameras, and instruct people in basic operation. What they write doesn't need to be 100% correct.

So now you are asking us to believe that every camera manufacturer has, by coincidence, used the same incorrect and misleading terminology without any of the company's engineers picking up on it!

I'll stick with using the term "ISO sensitivity". It makes good sense and accords with the common English usage of "sensitivity" in other contexts.

The very first paragraph of the Wikipedia article on film speed says:

Film speed is the measure of a photographic film's sensitivity to light, determined by sensitometry and measured on various numerical scales, the most recent being the ISO system. A closely related ISO system is used to describe the relationship between exposure and output image lightness in digital cameras.

A film's sensitivity relates the exposure to the density of the final negative. A digital camera's sensitivity relates the exposure to the lightness of the final image. Exactly analogous!

While there are certainly similarities between film speed and digital ISO, there certainly are a lot of differences.

According to the ISO standard digital ISO speed was designed to allow film photographers to easily switch to Digital. The purpose of Digital ISO is to "harmonize with film ISO speed ratings," Not to reflect what is actually going on. In other words the Digital ISO speed is intended to allow you to apply analog film workflows to digital cameras. It is not intended to be a perfect tool for natively shooting digital.

For instance, digital cameras can have a range of ISO Speeds, but only a single number is given in order to prevent confusion to those who want to think in film terms.

In terms of whether ISO is the same as sensitivity, the ISO standard itself specifically lists "ISO speed rating" and "standard output sensitivity (SOS)" as being separate attributes.

====

It is easy to get confused. If your mental model is that digital works the same as film, then digital ISO really does appear to be sensitivity. On the other hand, if you look at how digital cameras actually work, it is clear that it is not sensitivity.

If a digital sensor didn't record a photon at ISO 100, it likely would not have recorded that photon at ISO 64,000. Digital ISO really is like a teach trying to decide how to apply a curve to the results of a test. The ISO provides a mapping to tell us whether a particular photon count should map to a dark tone or a light tone. It doesn't change the number of photos counted.

 

[Michael Fryd]

...

Why do camera manufacturers promote an erroneous understanding of what ISO is and how it's used? I don't know. Nor do I particularly care. As long as they keep designing, manufacturing and selling outstanding products, I'm a happy guy.

...

Because it's an easy way to get people to understand what to expect using concepts they are already familiar with.

There's no downside to the manufacture as the wrong idea doesn't affect sales.

 

[Christof21]

There are no "generations" behind "exposure triangle", it is a recent thing (appeared circa 2003...

Surely you are referring to the term, not the concept.

The concept is demonstrably wrong (absurd would be a better word). Nothing like it was ever discussed among my colleagues.

The phrase was: for normal density, given film is rated xxx, you need yy exposure (a pair of shutter speed and f-stop, for example). Film speed was never understood as a part of exposure. The concept was density triangle, not exposure triangle; same like now it is default manufacturer rendering lightness triangle, not exposure triangle.

Going back to film cameras some had the EV on the same wheel as ISO (ASA or DIN) and some models didn't have EV at all, like Canon AV1. So I understand perfectly where the original statement comes from..

Not sure I understand what original statement you are referring too.

This

..the Zeiss manager explained: "If a photographer is manually controlling shutter speed and aperture, then the only way they have of further affecting exposure is ISO. So they can use the ISO dial as exposure compensation, effectively."

As I understand it's the one and only original statement in this thread..

I think I also understand, but that doesn't make what he said accurate. Exposure compensation changes exposure;

Not necessarily . For instance it does not do so in the scenario he mentions.

Exposure compensation is badly named, I had already created a thread about this topic. The only thing it does is altering the metering value.

 

[Tom Axford]

Use of the term, sensitivity, tends to reinforce the mistaken notion that ISO determines the sensitivity of the sensor; it's ability or efficiency to capture light. ISO does not determine sensitivity.

As far as I am aware, all the camera manufacturers refer to ISO as "ISO Sensitivity". So, presumably you would say that they have all misunderstood what ISO means and need to be re-educated!

Really, are you serious? The people who make cameras do not understand what ISO means?

Just to clarify, are you stating that ISO does control a sensor's sensitivity to light and that, as ISO is increased, a sensor becomes more sensitive to light?

No, I am not saying that. Most definitely not!

See my post just before yours. I am talking about the system sensitivity of the camera, meaning how much exposure is needed to produce a specified level of lightness in the final image. In other words, the sensitivity of the combination of the sensor plus all analogue and digital processing that takes place to produce the final image. In other words, treat the camera as a black box: light enters the lens and a digital image (jpeg or other format) comes out the other end. For measuring the ISO sensitivity I am not interested in how it works (i.e. what goes on inside the black box), just what goes in and what comes out.

It will capture more light during a shutter actuation than at the same settings but a lower ISO. Is that what you're saying?

No, I am not saying that (see above).

With respect to camera manufacturers, I've seen the same as you in both printed manuals and official online content. I've seen it in their educational content written specifically for photographers. This brings to mind an old saying. I may be paraphrasing but it goes something like this, "Just because all the kids are doing it, doesn't make it any less wrong."

Why do camera manufacturers promote an erroneous understanding of what ISO is and how it's used? I don't know. Nor do I particularly care. As long as they keep designing, manufacturing and selling outstanding products, I'm a happy guy.

I think they do it because they think it is correct. They see ISO sensitivity as defining the black box behaviour of the camera, as I described above.

I also don't assume that some entry-level employee who creates content for the company website has any better technical understanding of how cameras work than a reasonably experienced and well-informed enthusiast photographer. I've seen it too many times: sales and marketing staff have a way with words but all too often don't truly know or understand the product.

We don't have control over what the manufacturers write. But we do have some influence on how technical topics are discussed and explained in online community forums. Why shouldn't we make the effort to find a way to convey information in a conversational manner that is both accurate and empowering? Afterall, the better a person understands how their camera works, the better able they'll be to take full advantage of its potential.

I agree with you that it is best to convey information accurately and understandably. I think that they are doing this, provided ISO sensitivity is understood in the way I described above.

I also think that the average beginner photographer has no great difficulty in understanding the black-box view of a camera (light rays in, digital image out). It's some engineers who seem to be unable to stop themselves thinking in terms of sensors, amplifiers, A/D converters, etc, etc.

 

[Michael Fryd]

Use of the term, sensitivity, tends to reinforce the mistaken notion that ISO determines the sensitivity of the sensor; it's ability or efficiency to capture light. ISO does not determine sensitivity.

As far as I am aware, all the camera manufacturers refer to ISO as "ISO Sensitivity". So, presumably you would say that they have all misunderstood what ISO means and need to be re-educated!

Really, are you serious? The people who make cameras do not understand what ISO means?

Just to clarify, are you stating that ISO does control a sensor's sensitivity to light and that, as ISO is increased, a sensor becomes more sensitive to light?

No, I am not saying that. Most definitely not!

See my post just before yours. I am talking about the system sensitivity of the camera, meaning how much exposure is needed to produce a specified level of lightness in the final image. In other words, the sensitivity of the combination of the sensor plus all analogue and digital processing that takes place to produce the final image. In other words, treat the camera as a black box: light enters the lens and a digital image (jpeg or other format) comes out the other end. For measuring the ISO sensitivity I am not interested in how it works (i.e. what goes on inside the black box), just what goes in and what comes out.

...

Would you say that different grading curves changes the "sensitivity" of a test grading process?

With one curve 18 correct answers may give the student an "F". With another curve those same 18 correct answers might give the student an "A". Is this a "sensitivity" change or simply a different mapping of "correct answers" to "letter grades".

While it may seem off topic, it really isn't. The digital sensor is not measuring brightness or the intensity of the light. It is merely counting the photons that reach the sensor. The camera then refers to the ISO setting and maps these counts into image lightness.

Now it may seem that the count is proportional to image lightness, but that's not the case. The same scene illumination, same f/stop and same focal length will always yield the same level of light on the sensor, but the shutter speed will control how many photons are counted.

In fact changing the camera from f/4 at 1/30 to f/2.8 at 1/60 will double the light intensity on the sensor, but not change the number of photons counted.

At the same ISO both f/4 at 1/30 and f/2.8 at 1/60 will yield the same lightness in the final image, even though there are different levels of light hitting the sensor.

The inputs to the "digital camera as a black box" are photon counts, and the output is a lightnes level. They really are different things, There is no "amplification". There isn't achange in sensitivity (photon counts are independent of ISO). It's a mapping, like correct answers to letter grades.

 

[Lee Jay]

...

It would be a pretty rare shot that required Speed and Aperture to be fixed before ISO is thought about, I'm thinking.

Most of my shooting is that way. ISO gets set last, usually by the camera using Auto-ISO.

Exposure is what is affecting the quality, not the ISO setting. Now, of course, if one is foolish enough to needlessly set ISO manually first, to a value above base, that decision can put a limit on exposure, and hence on quality.

Gosh. How has anyone been able to take a decent digital photo over the last 20 years or so. It must of been dumb luck all this time. Good thing the photography world now has the likes of Lee Jay and yourself to set the unwashed masses straight.

(PS, in case you don't realize, I'm being sarcastic)

Maybe, instead of sarcasm, you could try learning.

Set your aperture based on the depth-of-field you need and/or stopping down for sharpness in some cases.

Set your shutter speed for the amount of motion blur you want to retain (often near zero, but not always).

Let ISO control image brightness.

 

[Iliah Borg]

There are no "generations" behind "exposure triangle", it is a recent thing (appeared circa 2003...

Surely you are referring to the term, not the concept.

The concept is demonstrably wrong (absurd would be a better word). Nothing like it was ever discussed among my colleagues.

The phrase was: for normal density, given film is rated xxx, you need yy exposure (a pair of shutter speed and f-stop, for example). Film speed was never understood as a part of exposure. The concept was density triangle, not exposure triangle; same like now it is default manufacturer rendering lightness triangle, not exposure triangle.

Going back to film cameras some had the EV on the same wheel as ISO (ASA or DIN) and some models didn't have EV at all, like Canon AV1. So I understand perfectly where the original statement comes from..

Not sure I understand what original statement you are referring too.

This

..the Zeiss manager explained: "If a photographer is manually controlling shutter speed and aperture, then the only way they have of further affecting exposure is ISO. So they can use the ISO dial as exposure compensation, effectively."

As I understand it's the one and only original statement in this thread..

I think I also understand, but that doesn't make what he said accurate. Exposure compensation changes exposure;

Not necessarily .

So what does it compensate than? Lightness? But in that case it is not exposure compensation, it is lightness compensation.

Exposure compensation is correctly named for what it does

 

[kiwi2]

Now it may seem that the count is proportional to image lightness, but that's not the case. The same scene illumination, same f/stop and same focal length will always yield the same level of light on the sensor, but the shutter speed will control how many photons are counted.

In fact changing the camera from f/4 at 1/30 to f/2.8 at 1/60 will double the light intensity on the sensor, but not change the number of photons counted.

At the same ISO both f/4 at 1/30 and f/2.8 at 1/60 will yield the same lightness in the final image, even though there are different levels of light hitting the sensor.

Do you think this is something profound?

Any photographer that understands stops and the exposure triangle knows this.

Why do you and a handful of other people feel the need to spend so much time continuing posting so much nonsense on this forum...???

 

[Mitrajoon]

I have the same problem on another forum I'm on. Some idiots keep insisting the Earth is round, but I can step out my door and see it's flat. What nonsense! Why can't they just keep quiet and let us walk in the knowledge we can never fall off.

--
Jim
http://jmlphotography.smugmug.com/
https://secure.flickr.com/photos/79977169@N04/