Poll: should we lie to beginners? II

[new boyz]

Good luck educating beginners with this complicated theory without confusing them. I would rather tell them "High ISO make your picture 'look' brighter, but in expense of possible reduction in DR, adding noise bla bla" and "the best ISO is the lowest, around 100-200, but avoid 50 bla bla" without the ISO-less sensor theory behind it. That's easier for them to chew. They are beginners after all. If they want to dig deeper, I'll recommend this series to them ( Is ISO part of exposure? Vol 1,2,3 and 4).

 

[bobn2]

new boyz wrote:

Good luck educating beginners with this complicated theory without confusing them.

The right theory is actually simpler than the one people use. The one people want to use makes dealing with exposure a three variable problem rather than a two variable one, and the graphic they use to illustrate it (the triangle) is completely meaningless.

 

[Andre Affleck]

moving_comfort wrote:

I ran into a situation related to this with my neighbor last year.

He had been told that shutter speed, aperture and ISO formed an exposure 'triangle', in that each was equally 'tweakable' to get more light on the sensor. (Thanks, National Camera Exchange clerk!)

He was basically under the impression that there was no downside to being lazy with aperture or shutter speed, because it could be made up with an ISO adjustment - that all three variables affected 'exposure'.

(In his defense, he wasn't really being lazy about aperture, he just had the consumer kit zoom and usually didn't have a lot of aperture range to work with.)

After I had a talk with him, he bought a Tamron 17-50 2.8 to get more aperture range to work with - and he started to notice noise, more, after that (he had upgraded from a P&S so he thought the noise he saw before was still 'pretty good'. ) He also bought a used 35 1.8G later.

I think there are a lot of shooters who have more of a clue than he did, and have been informed that you should perhaps carefully choose your SS and aperture first, and then let ISO make up the difference, but they know that because what's really happening with ISO has been partially described to them - which begs the question, if you're going have to partially describe it anyway, why not entirely, accurately describe it?

Of course it should be described accurately, but the question is, must it be? It was claimed by quite a few members that if you didn't understand the true essence of ISO, your photography would suffer. In fact one member said:

It is worse than wrong, it is misleading.

The problem is that the wrong understanding of what exposure means results in wrong decisions while shooting, and suboptimal results.

So far no examples of such.

People seem to come to the same conclusion and make the same decisions regardless, using the exposure triangle method. You may think this is trivial, but the implications are significant. This is why Human Factors engineers are never unemployed. Scientists, in their brilliants, often loose site of the prize. And we have 800 posts to prove it!

The implications may also help explain why some taught it that way, especially in the film days.

Photography is not a science like photometry. It's part art, part skill, and part science. Artists are often not good scientists. If they have a hard time with science, I say give them something tangible that they can use.

 

[Andre Affleck]

new boyz wrote:

Good luck educating beginners with this complicated theory without confusing them. I would rather tell them "High ISO make your picture 'look' brighter, but in expense of possible reduction in DR, adding noise bla bla" and "the best ISO is the lowest, around 100-200, but avoid 50 bla bla" without the ISO-less sensor theory behind it. That's easier for them to chew. They are beginners after all. If they want to dig deeper, I'll recommend this series to them ( Is ISO part of exposure? Vol 1,2,3 and 4). <-LOL

Bingo!

 

[Great Bustard]

Andre Affleck wrote:

new boyz wrote:

Good luck educating beginners with this complicated theory without confusing them. I would rather tell them "High ISO make your picture 'look' brighter, but in expense of possible reduction in DR, adding noise bla bla" and "the best ISO is the lowest, around 100-200, but avoid 50 bla bla" without the ISO-less sensor theory behind it. That's easier for them to chew. They are beginners after all. If they want to dig deeper, I'll recommend this series to them ( Is ISO part of exposure? Vol 1,2,3 and 4). <-LOL

Bingo!

• The exposure is a function of the amount of light falling on the sensor, and is determined by how bright the scene is, how wide the aperture is, and how long the shutter is open.
• The less light that falls on the sensor, the more noisy and dark the photo will be. For a given aperture, shutter speed, and/or flash power, to increase the brightness of the photo in-camera for the desired LCD playback / OOC jpg brightness, raise the ISO.
• On the other hand, if you're letting the camera decide the aperture, shutter speed, and/or flash power for you, then the camera will figure in how many stops underexposed you choose to be on the basis of the ISO setting you've chosen.

Yep, complicated and confusing.

 

[Great Bustard]

Andre Affleck wrote:

Great Bustard wrote:

Andre Affleck wrote:

As a continuation of this thread, I really want to focus on the impact on one's photography if taught incorrectly.

In the last thread I was specifically looking for scenario's where knowing the true definition of exposure and how it relates to ISO changed or helped your shooting habits.

Give me a scenario where gaining the insight that "ISO was not part of exposure" has led one to a better (or even different) decision than a person less enlightened.

Iliah Borg wrote:

I gave it recently. ISO speed bump clips the highlights. On the other hand the low brightness of an important part of a scene calls for an ISO bump if ISO is considered to be a part of something (anything). So in a scenario like a narrow alley in an old Italian town where the sky is bright and the walls on one side of the alley are very dark closer to the pavement it is worth to know that one does not need to bump the ISO speed.

And by the way, what ISO are we discussing, the red, green, or blue ISO? Daylight ISO or mercury vapor ISO?

GB already tried that scenario here. As in your scenario, the benefit to this technique comes purely from the understanding that lower ISOs retain more highlights, and not from how we define exposure. So photographers with less insight, who also saw that original thread, understood it as "if I use the same aperture and shutter speed, I can underexpose at ISO100 and push the shadows in post, only now retaining all the highlights as a correctly exposed shot at ISO3200". They came to the same conclusion as you without knowing the true definition of exposure.

You were right there, and missed it:

Nope, I was right there and nailed it. I purposely misused the definition.

Well done.

Ya'll just dancing around the fact that it doesn't matter whether ISO is part of exposure or not, shooting habits don't seem to change.

Then you are of the opinion that exposure is unimportant.

"if I use the same aperture and shutter speed, I can underexpose at ISO100 and push the shadows in post, only now retaining all the highlights as a correctly exposed shot at ISO3200"

That's it! So you are "underexposed" whether you are at ISO 100 or ISO 3200 for that particular shot,

And if you believe that only ISO 100 was underexposed and ISO 3200 was not, it still works!

Both were underexposed. If you'll recall, ISO is not part of exposure.

and all ISO 3200 does is push the shadows in camera rather than pushing in post.

What's the advantage of pushing in camera, then, when it blows highlights by pushing portions of the photo outside the bit depth of the image file? I'm glad you asked. First and foremost is that it will give the desired LCD playback and OOC jpg brightness (which could be done for the ISO 100 photo as well, if only an optional ISOless UI were implemented in firmware).

Secondly, for cameras using non-ISOless sensors, ISO 3200 will be less noisy than using ISO 100 and applying an "aggressive" tone curve, since the read noise (the noise from the sensor and supporting hardware) is significantly less at ISO 3200 than it is at ISO 100.

Any more?

That about covers it!

Yeah -- that.

 

[Andre Affleck]

Great Bustard wrote:

Andre Affleck wrote:

Great Bustard wrote:

Andre Affleck wrote:

As a continuation of this thread, I really want to focus on the impact on one's photography if taught incorrectly.

In the last thread I was specifically looking for scenario's where knowing the true definition of exposure and how it relates to ISO changed or helped your shooting habits.

Give me a scenario where gaining the insight that "ISO was not part of exposure" has led one to a better (or even different) decision than a person less enlightened.

Iliah Borg wrote:

I gave it recently. ISO speed bump clips the highlights. On the other hand the low brightness of an important part of a scene calls for an ISO bump if ISO is considered to be a part of something (anything). So in a scenario like a narrow alley in an old Italian town where the sky is bright and the walls on one side of the alley are very dark closer to the pavement it is worth to know that one does not need to bump the ISO speed.

And by the way, what ISO are we discussing, the red, green, or blue ISO? Daylight ISO or mercury vapor ISO?

GB already tried that scenario here. As in your scenario, the benefit to this technique comes purely from the understanding that lower ISOs retain more highlights, and not from how we define exposure. So photographers with less insight, who also saw that original thread, understood it as "if I use the same aperture and shutter speed, I can underexpose at ISO100 and push the shadows in post, only now retaining all the highlights as a correctly exposed shot at ISO3200". They came to the same conclusion as you without knowing the true definition of exposure.

You were right there, and missed it:

Nope, I was right there and nailed it. I purposely misused the definition.

Well done.

Ya'll just dancing around the fact that it doesn't matter whether ISO is part of exposure or not, shooting habits don't seem to change.

Then you are of the opinion that exposure is unimportant.

"if I use the same aperture and shutter speed, I can underexpose at ISO100 and push the shadows in post, only now retaining all the highlights as a correctly exposed shot at ISO3200"

That's it! So you are "underexposed" whether you are at ISO 100 or ISO 3200 for that particular shot,

And if you believe that only ISO 100 was underexposed and ISO 3200 was not, it still works!

Both were underexposed. If you'll recall, ISO is not part of exposure.

Why is this so hard for you to understand? I am *postulating* that if one did not understand this to be true, the same conclusion is drawn. Agreed?

 

[Andre Affleck]

bobn2 wrote:

new boyz wrote:

Good luck educating beginners with this complicated theory without confusing them.

The right theory is actually simpler than the one people use.

It depends how it's presented. Look here at a link that was referenced before as being flawed. It's is definitely flawed, but it gave the reader the general concepts. Now look at what you wrote as a comment to the author:

Sorry Nasim, this article is wrong in several fundamental ways. ISO is not ‘the level of sensitivity of your camera to available light’ and the sensitivity of a digital camera’s sensor never changes. The ISO Exposure Index, which is its proper name, only describes a relationship between scene brightness and final image brightness, and has no connection to the sensor’s ability to collect light. A sensor does not have an ISO rating at all. By increasing the ISO setting on your camera, you do not enable it to capture more light. In most, you don’t change the way it captures light at all, all you change is the way the raw file is converted into an image (JPEG) file. In some, raising the ISO results in less electronic noise being added to the image. The noise you see in images taken in low light is not caused by the ISO setting, it is caused by the small number of photons making up the picture.
Bob.

I asked a friend of mine last night who is trying to learn photography to read the article, then read your comment. His exact words were, "now I'm completely confused".

 

[Andre Affleck]

Great Bustard wrote:

Andre Affleck wrote:

new boyz wrote:

Good luck educating beginners with this complicated theory without confusing them. I would rather tell them "High ISO make your picture 'look' brighter, but in expense of possible reduction in DR, adding noise bla bla" and "the best ISO is the lowest, around 100-200, but avoid 50 bla bla" without the ISO-less sensor theory behind it. That's easier for them to chew. They are beginners after all. If they want to dig deeper, I'll recommend this series to them ( Is ISO part of exposure? Vol 1,2,3 and 4). <-LOL

Bingo!

• The exposure is a function of the amount of light falling on the sensor, and is determined by how bright the scene is, how wide the aperture is, and how long the shutter is open.
• The less light that falls on the sensor, the more noisy and dark the photo will be. For a given aperture, shutter speed, and/or flash power, to increase the brightness of the photo in-camera for the desired LCD playback / OOC jpg brightness, raise the ISO.
• On the other hand, if you're letting the camera decide the aperture, shutter speed, and/or flash power for you, then the camera will figure in how many stops underexposed you choose to be on the basis of the ISO setting you've chosen.

Yep, complicated and confusing.

See my response here and here.

 

[PhilPreston3072]

bobn2 wrote:

I get a 'good exposure' by simply setting a 'good exposure'. I use the camera's base ISO setting to preserve as much of the data resulting from that exposure as I can. That has nothing to do with the ISO that will result from the exposure that I use when I finally process it.

So wouldn't you get the same 'brightness' by using the exact same ISO in camera that you used in post?

From what I see, for any given shutter and aperture combination, you require an appropriate value of ISO to have appropriate exposure/brightness.

 

[bobn2]

PhilPreston3072 wrote:

bobn2 wrote:

I get a 'good exposure' by simply setting a 'good exposure'. I use the camera's base ISO setting to preserve as much of the data resulting from that exposure as I can. That has nothing to do with the ISO that will result from the exposure that I use when I finally process it.

So wouldn't you get the same 'brightness' by using the exact same ISO in camera that you used in post?

Since ISO maps exposure to brightness, by definition if you have the same exposure and brightness, you have the same ISO. Or vice versa.

From what I see, for any given shutter and aperture combination, you require an appropriate value of ISO to have appropriate exposure/brightness.

For every exposure (shutter, aperture, scene illuminance) there is an ISO which will give you the normalised ISO brightness. That simply comes from the definition of ISO, above - ISO is a function of exposure to brightness.

 

[Murmillo]

Sammy Yousef wrote:

bobn2 wrote:

Could you please explain where the 'points' on the exposure triangle are, preferably with a little diagram, please? I'm interested in how exposure triangle space is defined, and what the dimensions are.

Why on earth would I do that for you? You've already rubbished the whole concept. There are plenty of good sites on the Internet that already have this information, and which you have already disparaged.

Bob has done nothing of the sort Sammy; it is your reaction to what you simply refuse to understand & learn that is "rubbishing" these forums.

In any case where I have won a point in arguing with you, you simply dismiss the argument I have made with rhetoric, end up getting personal or ignore it.

It is you who is going "personal", give it a rest already.

Furthermore the leading nature of the questions in your polls demonstrate clearly that you are not interested in any kind of open intellectually honest debate and have already made up your mind.

You can't assume all people - especially on a technical board - are complete idiots. Many if not most will see through your nonsense.

This exactly what you are doing. How……"nice" of you

People complain that I write too much but you clearly have WAY more time on your hands than I do.

Your posting history proves the contrary; but it doesn't matter to you anyway.

Sammy don't take it personal just because somebody is trying to rectify habitual errors (yours & other persons of course) in exposure technique; learning starts when you open your mind to the possibility that you are wrong; & when realising your knowledge on a subject is limited, choosing to learn instead of mud-slinging.

 

[bgD300]

and if you don't understand the craft you won't be much of an artist. Creativity is stretching or outright breaking the rules to achieve something.

Using selective DOF as an element in an image is one thing, just having an OOF image because you don't understand shutter speed vs. aperture is quite another.

 

[moving_comfort]

Andre Affleck wrote:

moving_comfort wrote:

I ran into a situation related to this with my neighbor last year.

He had been told that shutter speed, aperture and ISO formed an exposure 'triangle', in that each was equally 'tweakable' to get more light on the sensor. (Thanks, National Camera Exchange clerk!)

He was basically under the impression that there was no downside to being lazy with aperture or shutter speed, because it could be made up with an ISO adjustment - that all three variables affected 'exposure'.

(In his defense, he wasn't really being lazy about aperture, he just had the consumer kit zoom and usually didn't have a lot of aperture range to work with.)

After I had a talk with him, he bought a Tamron 17-50 2.8 to get more aperture range to work with - and he started to notice noise, more, after that (he had upgraded from a P&S so he thought the noise he saw before was still 'pretty good'. ) He also bought a used 35 1.8G later.

I think there are a lot of shooters who have more of a clue than he did, and have been informed that you should perhaps carefully choose your SS and aperture first, and then let ISO make up the difference, but they know that because what's really happening with ISO has been partially described to them - which begs the question, if you're going have to partially describe it anyway, why not entirely, accurately describe it?

Of course it should be described accurately, but the question is, must it be?...

Photography is not a science like photometry. It's part art, part skill, and part science. Artists are often not good scientists. If they have a hard time with science, I say give them something tangible that they can use.

Like:

"Upping ISO is not affecting exposure, it's adding brightness to the image artificially after the image is captured and before it is saved. That is why... (add your usual instructional caveats/warnings to increasing ISO that you normally would give them here...)"

How could it get any simpler? This ^^ at least points in a more accurate direction, and would help them with the underpinnings of 'exposure'.

.

.

 

[bobn2]

moving_comfort wrote:

Andre Affleck wrote:

moving_comfort wrote:

I ran into a situation related to this with my neighbor last year.

He had been told that shutter speed, aperture and ISO formed an exposure 'triangle', in that each was equally 'tweakable' to get more light on the sensor. (Thanks, National Camera Exchange clerk!)

He was basically under the impression that there was no downside to being lazy with aperture or shutter speed, because it could be made up with an ISO adjustment - that all three variables affected 'exposure'.

(In his defense, he wasn't really being lazy about aperture, he just had the consumer kit zoom and usually didn't have a lot of aperture range to work with.)

After I had a talk with him, he bought a Tamron 17-50 2.8 to get more aperture range to work with - and he started to notice noise, more, after that (he had upgraded from a P&S so he thought the noise he saw before was still 'pretty good'. ) He also bought a used 35 1.8G later.

I think there are a lot of shooters who have more of a clue than he did, and have been informed that you should perhaps carefully choose your SS and aperture first, and then let ISO make up the difference, but they know that because what's really happening with ISO has been partially described to them - which begs the question, if you're going have to partially describe it anyway, why not entirely, accurately describe it?

Of course it should be described accurately, but the question is, must it be?...

Photography is not a science like photometry. It's part art, part skill, and part science. Artists are often not good scientists. If they have a hard time with science, I say give them something tangible that they can use.

Like:

"Upping ISO is not affecting exposure, it's adding brightness to the image artificially after the image is captured and before it is saved. That is why... (add your usual instructional caveats/warnings to increasing ISO that you normally would give them here...)"

How could it get any simpler? This ^^ at least points in a more accurate direction, and would help them with the underpinnings of 'exposure'.

The word 'artificially' is redundant. A raw file has no brightness, it's brightness depends entirely on how you process it - so all processing choices are as valid as each other, the only question is which one of those choices ends up with the output looking realistically 'bright', on the understanding that the amount of light entering the eye from the reproduced image bears no direct relation to the amount of light that would have entered from the original scene.

 

[PhilPreston3072]

bobn2 wrote:

PhilPreston3072 wrote:

So wouldn't you get the same 'brightness' by using the exact same ISO in camera that you used in post?

Since ISO maps exposure to brightness, by definition if you have the same exposure and brightness, you have the same ISO. Or vice versa.

Therefore ISO (or gain in video terms) still has its part in determining the final brightness/exposure.

From what I see, for any given shutter and aperture combination, you require an appropriate value of ISO to have appropriate exposure/brightness.

For every exposure (shutter, aperture, scene illuminance) there is an ISO which will give you the normalised ISO brightness. That simply comes from the definition of ISO, above - ISO is a function of exposure to brightness.

Which means that even if I alter the shutter or aperture parameters, I can still obtain the same final brightness/exposure by altering ISO accordingly. Isn't that how the exposure triangle works?

 

[bobn2]

PhilPreston3072 wrote:

bobn2 wrote:

PhilPreston3072 wrote:

So wouldn't you get the same 'brightness' by using the exact same ISO in camera that you used in post?

Since ISO maps exposure to brightness, by definition if you have the same exposure and brightness, you have the same ISO. Or vice versa.

Therefore ISO (or gain in video terms) still has its part in determining the final brightness/exposure.

No, because ISO maps exposure to brightness. So, you can't just write 'exposure/brightness'. Different ISOs will give you different brightnesses from the same exposure. So, ISO determines which brightness you get from a given exposure.

From what I see, for any given shutter and aperture combination, you require an appropriate value of ISO to have appropriate exposure/brightness.

For every exposure (shutter, aperture, scene illuminance) there is an ISO which will give you the normalised ISO brightness. That simply comes from the definition of ISO, above - ISO is a function of exposure to brightness.

Which means that even if I alter the shutter or aperture parameters, I can still obtain the same final brightness/exposure by altering ISO accordingly. Isn't that how the exposure triangle works?

You've conflated 'brightness' and 'exposure' again.

 

[Great Bustard]

Andre Affleck wrote:

Great Bustard wrote:

Andre Affleck wrote:

Great Bustard wrote:

Andre Affleck wrote:

As a continuation of this thread, I really want to focus on the impact on one's photography if taught incorrectly.

In the last thread I was specifically looking for scenario's where knowing the true definition of exposure and how it relates to ISO changed or helped your shooting habits.

Give me a scenario where gaining the insight that "ISO was not part of exposure" has led one to a better (or even different) decision than a person less enlightened.

Iliah Borg wrote:

I gave it recently. ISO speed bump clips the highlights. On the other hand the low brightness of an important part of a scene calls for an ISO bump if ISO is considered to be a part of something (anything). So in a scenario like a narrow alley in an old Italian town where the sky is bright and the walls on one side of the alley are very dark closer to the pavement it is worth to know that one does not need to bump the ISO speed.

And by the way, what ISO are we discussing, the red, green, or blue ISO? Daylight ISO or mercury vapor ISO?

GB already tried that scenario here. As in your scenario, the benefit to this technique comes purely from the understanding that lower ISOs retain more highlights, and not from how we define exposure. So photographers with less insight, who also saw that original thread, understood it as "if I use the same aperture and shutter speed, I can underexpose at ISO100 and push the shadows in post, only now retaining all the highlights as a correctly exposed shot at ISO3200". They came to the same conclusion as you without knowing the true definition of exposure.

You were right there, and missed it:

Nope, I was right there and nailed it. I purposely misused the definition.

Well done.

Ya'll just dancing around the fact that it doesn't matter whether ISO is part of exposure or not, shooting habits don't seem to change.

Then you are of the opinion that exposure is unimportant.

"if I use the same aperture and shutter speed, I can underexpose at ISO100 and push the shadows in post, only now retaining all the highlights as a correctly exposed shot at ISO3200"

That's it! So you are "underexposed" whether you are at ISO 100 or ISO 3200 for that particular shot,

And if you believe that only ISO 100 was underexposed and ISO 3200 was not, it still works!

Both were underexposed. If you'll recall, ISO is not part of exposure.

Why is this so hard for you to understand? I am *postulating* that if one did not understand this to be true, the same conclusion is drawn. Agreed?

I apologize if I'm misinterpreting. Could you restate the point you are trying to make? Thanks, and sorry for missing the point.

 

[gollywop]

PhilPreston3072 wrote:

bobn2 wrote:

I get a 'good exposure' by simply setting a 'good exposure'. I use the camera's base ISO setting to preserve as much of the data resulting from that exposure as I can. That has nothing to do with the ISO that will result from the exposure that I use when I finally process it.

So wouldn't you get the same 'brightness' by using the exact same ISO in camera that you used in post?

Pretty much so. The only problem is that you don't know the ISO that you would find best during processing at the time you're taking the shot. So there's a danger that you would set the in-camera ISO too high. That's one of the real advantages in doing the brightening during processing.

From what I see, for any given shutter and aperture combination, you require an appropriate value of ISO to have appropriate exposure/brightness.

In a very loose (broadly interpreted) sense of ISO that is correct. If your desired exposure at base ISO is not ETTR, and the resulting image would be darker than desired, then some ISO must be added somewhere, ether in-camera or during processing. If, on the other hand, you have an acceptable ETTR exposure at base ISO that is too bright, then you are going to want to shoot at that exposure and apply "negative ISO," i.e., reduced brightening during processing.

The latter case is the one that originally brought attention to ETTR, a concept, however, that has more general applicability and advantage.

I am assuming above, by the way, that one is shooting raw and that a "desired exposure" is one having a desired f-ratio and SS, and that an "acceptable exposure" is one whose aperture and SS are within acceptable values.



--
gollywop

 

[moving_comfort]

Great Bustard wrote:

Andre Affleck wrote:

Great Bustard wrote:

Andre Affleck wrote:

Great Bustard wrote:

Andre Affleck wrote:

As a continuation of this thread, I really want to focus on the impact on one's photography if taught incorrectly.

In the last thread I was specifically looking for scenario's where knowing the true definition of exposure and how it relates to ISO changed or helped your shooting habits.

Give me a scenario where gaining the insight that "ISO was not part of exposure" has led one to a better (or even different) decision than a person less enlightened.

Iliah Borg wrote:

I gave it recently. ISO speed bump clips the highlights. On the other hand the low brightness of an important part of a scene calls for an ISO bump if ISO is considered to be a part of something (anything). So in a scenario like a narrow alley in an old Italian town where the sky is bright and the walls on one side of the alley are very dark closer to the pavement it is worth to know that one does not need to bump the ISO speed.

And by the way, what ISO are we discussing, the red, green, or blue ISO? Daylight ISO or mercury vapor ISO?

GB already tried that scenario here. As in your scenario, the benefit to this technique comes purely from the understanding that lower ISOs retain more highlights, and not from how we define exposure. So photographers with less insight, who also saw that original thread, understood it as "if I use the same aperture and shutter speed, I can underexpose at ISO100 and push the shadows in post, only now retaining all the highlights as a correctly exposed shot at ISO3200". They came to the same conclusion as you without knowing the true definition of exposure.

You were right there, and missed it:

Nope, I was right there and nailed it. I purposely misused the definition.

Well done.

Ya'll just dancing around the fact that it doesn't matter whether ISO is part of exposure or not, shooting habits don't seem to change.

Then you are of the opinion that exposure is unimportant.

"if I use the same aperture and shutter speed, I can underexpose at ISO100 and push the shadows in post, only now retaining all the highlights as a correctly exposed shot at ISO3200"

That's it! So you are "underexposed" whether you are at ISO 100 or ISO 3200 for that particular shot,

And if you believe that only ISO 100 was underexposed and ISO 3200 was not, it still works!

Both were underexposed. If you'll recall, ISO is not part of exposure.

Why is this so hard for you to understand? I am *postulating* that if one did not understand this to be true, the same conclusion is drawn. Agreed?

I apologize if I'm misinterpreting. Could you restate the point you are trying to make? Thanks, and sorry for missing the point.

.

I think he's saying that if you witness the sun moving across the sky it doesn't matter if you think it revolves around the earth or if the earth is turning on it's axis, you can come to the same conclusion - that you will see it again, in roughly the same place and almost the same time, the next morning.

He's also implying that to most people, there's no practical reason that they need to know the difference between the earth rotating on it's axis and the sun revolving around the earth - the observable effects, as far as everyone is concerned, are the same.

There is a minor point there. It's an odious, depressing point that rewards irrationality and ignorance... But it's a point.

However it doesn't strictly apply to this argument, as keeping ISO as a full light-gathering member of the exposure triangle (or whatever) can lead to misconceptions that can bite you in practical ways.

.

--
Here are a few of my favorite things...
---> http://www.flickr.com/photos/95095968@N00/sets/72157626171532197/