The Recent F/stop Controversy

Started 2 months ago | Discussions
riveredger Veteran Member • Posts: 3,369
Re: The Recent F/stop Controversy

Michael Fryd wrote:

mamallama wrote:

...

Wow!! I just signed a $15,000 contract with a professional wedding photographer for my daughter and I hope he has all this stuff down pat. Otherwise I will be disappointed in the results.

Don't worry. Photographers have been using f/stops for years. We're smart and can take great photos even when the equipment isn't helping us as much as it can.

It's quite possible to take great photos when you misunderstand the underlying technology. As long as your mental model gives you reasonable guidance in your situation you're going to get good results. However, if the mental model is wrong, it can give you bad advice in challenging situations.

The standard example is that higher ISO settings cause more image noise. As a rule of thumb this works in common situations. A wedding photographer could produce great results with this misunderstanding.

The problem is what happens in a difficult situation. The photographer sees an opportunity for a fantastic shot, but his camera tells him he needs ISO 3200, and the photographer doesn't want that much noise. His guideline is that the ISO setting causes the noise, to he makes sure his camera is set to capture raw, sets the ISO to 800, and plans to raise the brightness in post processing. His mental model tells him this trick will decrease visible noise as he has selected a lower ISO. In reality it won't help, and may increase visible noise.

As you understand more about the technology, you gain the ability to overcome more challenges. However, with today's modern gear, you don't need to understand very much to shoot in easy situations.

I think you need to take a break.

Pixel Pooper Veteran Member • Posts: 3,142
Re: The Recent F/stop Controversy

Michael Fryd wrote:

fferreres wrote:

...

If you state that one would say one is better using the value that's relevant, you are stating that the use of f-stop is irrelevant for everyone. You are generalizing to everyone, not just to your case and workflow.

I am not stating it's irrelevant for everyone. I am stating that things are easier if you use a different framework for the discussion.

When explaining how things work we should talk about angle of view and aperture diameter. There is no need to get into the specifics of sensor size or focal length.

Consider the following diagram.

Using the model of angle of view and aperture diameter, it is clear that both diagrams will produce the same results.

They will produce equivalent results in some situations, but you're not telling the whole story.

They have the same aperture diameter and same angle of view. Therefore they capture the same total light. It really doesn't matter whether the sensor is small and close to the lens, or larger and further from the lens. That's an implementation detail.

It does matter because the smaller sensor collects the same total light over a smaller area, so it receives a larger exposure. This means that the smaller sensor needs to use a lower ISO. If the smaller sensor can not be set to a proportionally lower ISO, it will be overexposed and you will ruin the picture. That's not an implementation detail, it is a consequence of ignoring exposure.

However, if we teach f/stops, focal lengths, ISO values, etc., it becomes difficult to explain why the above two produce about the same result. After all the focal lengths, f/stops, and sensor sizes are all different.

You are fixated on achieving equivalent results from two different formats, but what do you do if you just have one camera? When there is no other camera that you need to be equivalent with, how does aperture diameter and angle of view make it easier to choose your camera settings? What is your workflow for taking a picture that does not rely on exposure or f/stops?

LoneTree1 Senior Member • Posts: 1,157
Re: Disingenuous posting

fferreres wrote:

Great Bustard wrote:

kiwi2 wrote:

Great Bustard wrote:

Michael Fryd wrote:

kiwi2 wrote:

Why exactly should I be worried about achieving equivalence between the two..??

You shouldn't be concerned about equivalence between these two.

It's weird that so many [intentionally] misrepresent Equivalence saying that they should be shooting Equivalent photos on different formats, even though Equivalence *explicitly* says quite the opposite. It's as if someone said to multiply mi/hr by 1.6 to get km/hr, and they said, "Why should I drive the same speed in Europe as I do in the US?"

So now with a real world example, it suddenly doesn't matter any more...???

Remember when Richard Butler said to you:

Disingenuous posting

It's already been made clear in one thread that no one is saying that the f-number of a lens actually changes and that the standard exposure model is based, for better or worse, on f-numbers and light per unit area.

So no, no one is saying that the f-number "becomes" something else. Or "is" something else on a different sensor. You repeatedly reverting to that claim is clearly disingenuous.

You've made apparent that you know this already. You're also seemingly aware that equivalence doesn't claim it, and that there is some value to a whole-image understanding of total light.

If you continue to intentionally misrepresent the idea of equivalence, purely because you want to play games of semantics or because you've decided you don't deem it useful, this thread will be deleted.

Do you remember that? You're doing the *exact same BS* again. Where does Equivalence say, or imply, that one should use one system to get photos Equivalent to photos taken with another system? Where does Equivalence say, or imply, that the differences between System A and System B are *necessarily* going to be so significant that one *must* take Equivalence into account with each and every photo?

Once again, your are *intentionally* misrepresenting what Equivalence says/implies. Your straw man argument is *exactly* like me posting a photo of a scene at f/4 1/400 ISO 100 and f/8 1/100 ISO 400 that look all but identical and then making the specious claim that there's no difference between f/4 and f/8, no difference between 1/400 and 1/100, and no difference between ISO 100 and ISO 400. And you do this kind of ++++ all the freakin' time!

He did not missrepresent anything. Actually, nobody is opposed to the idea of equivalence. And Richard Butler's own articles about it is probably the bible to understand it. But you remembering a very old post un bringing it an unrelated thread as a threat is something sad.

The problem comes when things that are Equivalent are tried to made Equal. And when in trying to made Equal, they try to reinvent photography by designating lenses with FOV and f-milimeters. Nobody argues about any logical argument of what could eventually compare to something else, as in one dollar in terms of yuans.

Equivalence.

Yes, larger sensors show larger fields of view with the same lens.

Yes, larger sensors have shallower DOF with the same f.l. lens set at the same aperture and used with a smaller sensor.

Yes, provided the pixel counts are equal, a smaller sensor can resolve more per unit area with the same lens focal length used on a larger sensor.

Yes, a larger sensor renders a less noisy image at the same ISO as a smaller one, provided pixel counts are similar (which is directly related to pixel SIZE).

NO, a larger sensor collecting more light over its area has no special benefits over a smaller sensor other than that already covered.

Greater total light gathering due to sensor size impacts NOTHING, everything is predicated by pixel size, lens speed and exposure time.

Great Bustard Forum Pro • Posts: 42,986
Re: Yep, that's the modern world, all right.

fferreres wrote:

Great Bustard wrote:

[Photographic] Equivalence is a paradigm that relates the visual properties of photos of a given scene from different formats based on perspective, framing, and the diameter of the [effective] aperture.

...

no more or less helpful in understanding what Equivalence is about than, say, a single sentence definition of Capitalism:

an economic system characterized by private or corporate ownership of capital goods, by investments that are determined by private decision, and by prices, production, and the distribution of goods that are determined mainly by competition in a free market

I have an alternative definition:

Photographic equivalence provides some rules of thumb to assess how a shot in certain format could have been shot in a different one and still look quite the same.

I suppose your alternative definition for capitalism might go something like:

Capitalism provides some rules of thumb on how the government and people interact with regards to business transactions, how labor is compensated, and the possession of goods property.

Great Bustard Forum Pro • Posts: 42,986
Re: Yep, that's the modern world, all right.

mamallama wrote:

Great Bustard wrote:

mamallama wrote:

Great Bustard wrote:

mamallama wrote:

Great Bustard wrote:

mamallama wrote:

I love the clarity when just the mention of equivalence results in multiple threads that limit out at 150. A concise one sentence definition of equivalence might help the clarity.

If you can't say it all in a Twitter post, then it isn't worth saying -- that's the world we now live in. Maybe if I ask the POTUS, he can do it just for you.

Now I know why it isn't worth saying.

Well, you were the one asking for the Twitter post version to get some clarity. So the three bullet points I gave:

  • For a given exposure, more light is projected on a larger sensor.
  • For a given scene, DOF, and exposure time, the same amount of light is projected on all sensors, regardless of size.
  • Thus, the only way for a larger sensor to collect more light is to use a more shallow DOF or longer exposure time.

were too much of a chore for you -- you wanted a "concise one sentence definition of equivalence" in order to have "clarity", but now say that a one sentence definition isn't worth saying because it reflects the same mindset of someone whose politics you don't like. Oh well -- can't please them all, I suppose.

Sorry, that is not a one sentence definition.

No kidding -- I said that my three bullet points "were too much of a chore for you" because you wanted a single sentence. But when I noted that the POTUS is the king of single sentence explanations, you said, "Now I know why it isn't worth saying". But, if you must have a single sentence, here it is:

[Photographic] Equivalence is a paradigm that relates the visual properties of photos of a given scene from different formats based on perspective, framing, and the diameter of the [effective] aperture.

At least we know you are thinking of it as a paradigm.

It wasn't a secret:

A common criticism of Equivalence is that some people say that it does nothing to help them to take better pictures. However, Equivalence is simply a framework by which to compare the IQ of different formats on the basis of six visual properties that are independent of the technology -- the same perspective, framing, DOF / diffraction / total amount of light on the sensor, exposure time (motion blur), lightness, and display dimensions. Equivalence is not an "instruction manual" for how to take a photo, but rather a comparison point for photographs from different systems.

The description of the paradigm is rather vague, however.

Which is exactly what I said below:

.

Go back and read what I asked for.

There's your single sentence and is no more or less helpful in understanding what Equivalence is about than, say, a single sentence definition of Capitalism:

an economic system characterized by private or corporate ownership of capital goods, by investments that are determined by private decision, and by prices, production, and the distribution of goods that are determined mainly by competition in a free market

But, for those for whom the definition as given is too much to handle:

Equivalent photos are photos of a given scene that have the:

As a corollary, Equivalent lenses are lenses that produce Equivalent photos on the format they are used on which means they will have the same AOV (angle of view) and the same aperture diameter. The following rules of thumb, which are a consequence of the above definition, are also helpful to understand:

  • For a given exposure, more light is projected on a larger sensor.
  • For a given scene, DOF, and exposure time, the same amount of light is projected on all sensors, regardless of size.
  • Thus, the only way for a larger sensor to collect more light is to use a more shallow DOF or longer exposure time.

What can you do, right?  It's definitely longer than a sentence or two, so I guess that limits its utility to less than 1% of the population, right?

Great Bustard Forum Pro • Posts: 42,986
Re: Disingenuous posting
1

fferreres wrote:

Great Bustard wrote:

kiwi2 wrote:

Great Bustard wrote:

Michael Fryd wrote:

kiwi2 wrote:

Why exactly should I be worried about achieving equivalence between the two..??

You shouldn't be concerned about equivalence between these two.

It's weird that so many [intentionally] misrepresent Equivalence saying that they should be shooting Equivalent photos on different formats, even though Equivalence *explicitly* says quite the opposite. It's as if someone said to multiply mi/hr by 1.6 to get km/hr, and they said, "Why should I drive the same speed in Europe as I do in the US?"

So now with a real world example, it suddenly doesn't matter any more...???

Remember when Richard Butler said to you:

Disingenuous posting

It's already been made clear in one thread that no one is saying that the f-number of a lens actually changes and that the standard exposure model is based, for better or worse, on f-numbers and light per unit area.

So no, no one is saying that the f-number "becomes" something else. Or "is" something else on a different sensor. You repeatedly reverting to that claim is clearly disingenuous.

You've made apparent that you know this already. You're also seemingly aware that equivalence doesn't claim it, and that there is some value to a whole-image understanding of total light.

If you continue to intentionally misrepresent the idea of equivalence, purely because you want to play games of semantics or because you've decided you don't deem it useful, this thread will be deleted.

Do you remember that? You're doing the *exact same BS* again. Where does Equivalence say, or imply, that one should use one system to get photos Equivalent to photos taken with another system? Where does Equivalence say, or imply, that the differences between System A and System B are *necessarily* going to be so significant that one *must* take Equivalence into account with each and every photo?

Once again, your are *intentionally* misrepresenting what Equivalence says/implies. Your straw man argument is *exactly* like me posting a photo of a scene at f/4 1/400 ISO 100 and f/8 1/100 ISO 400 that look all but identical and then making the specious claim that there's no difference between f/4 and f/8, no difference between 1/400 and 1/100, and no difference between ISO 100 and ISO 400. And you do this kind of ++++ all the freakin' time!

He did not missrepresent anything.

He did. He posted two photos of a scene where the differences were inconsequential implying that Equivalence *as a whole* was useless, just as if I had posted two photos of a scene at f/4 1/400 ISO 100 and f/8 1/100 ISO 400 that look all but identical and then making the specious claim that there's no difference between f/4 and f/8, no difference between 1/400 and 1/100, and no difference between ISO 100 and ISO 400, as I said in the last paragraph.

Actually, nobody is opposed to the idea of equivalence.

Actually, quite a few people are.

And Richard Butler's own articles about it is probably the bible to understand it. But you remembering a very old post un bringing it an unrelated thread as a threat is something sad.

"Threat"? Are you kidding me? There is no "threat", implied or otherwise. It was simply showing that he's been misrepresenting Equivalence for quite some time and continues to do so.

The problem comes when things that are Equivalent are tried to made Equal. And when in trying to made Equal, they try to reinvent photography by designating lenses with FOV and f-milimeters.

That, too, is an outright misrepresentation of Equivalence -- it does no such thing. Equivalence *absolutely does not* say, or imply, to "reinvent photography by designating lenses with FOV and f-milimeters".  There are *individuals* who would like to change the lens markings as such, but Equivalence does not advocate this.

Nobody argues about any logical argument of what could eventually compare to something else, as in one dollar in terms of yuans.

People deny Equivalence all the time.  One of my favorite denier quotes is, "If you have any evidence to support your theory of total light, it's just a coincidence".

Great Bustard Forum Pro • Posts: 42,986
Re: The Recent F/stop Controversy
1

kiwi2 wrote:

Michael Fryd wrote;

I would say that for digital photographers the actual aperture diameter is more important than the ratio of focal length to diameter.

Nonsense.

As much as it pains me to do so, I will have to agree with kiwi2, here.  That said, I would absolutely not object to a camera having an additional mode where one could specify the effective aperture to complement the current mode where the photographer specifies the relative aperture.

mamallama
mamallama Forum Pro • Posts: 55,889
Re: Yep, that's the modern world, all right.

Great Bustard wrote:

mamallama wrote:

Great Bustard wrote:

mamallama wrote:

Great Bustard wrote:

mamallama wrote:

Great Bustard wrote:

mamallama wrote:

I love the clarity when just the mention of equivalence results in multiple threads that limit out at 150. A concise one sentence definition of equivalence might help the clarity.

If you can't say it all in a Twitter post, then it isn't worth saying -- that's the world we now live in. Maybe if I ask the POTUS, he can do it just for you.

Now I know why it isn't worth saying.

Well, you were the one asking for the Twitter post version to get some clarity. So the three bullet points I gave:

  • For a given exposure, more light is projected on a larger sensor.
  • For a given scene, DOF, and exposure time, the same amount of light is projected on all sensors, regardless of size.
  • Thus, the only way for a larger sensor to collect more light is to use a more shallow DOF or longer exposure time.

were too much of a chore for you -- you wanted a "concise one sentence definition of equivalence" in order to have "clarity", but now say that a one sentence definition isn't worth saying because it reflects the same mindset of someone whose politics you don't like. Oh well -- can't please them all, I suppose.

Sorry, that is not a one sentence definition.

No kidding -- I said that my three bullet points "were too much of a chore for you" because you wanted a single sentence. But when I noted that the POTUS is the king of single sentence explanations, you said, "Now I know why it isn't worth saying". But, if you must have a single sentence, here it is:

[Photographic] Equivalence is a paradigm that relates the visual properties of photos of a given scene from different formats based on perspective, framing, and the diameter of the [effective] aperture.

At least we know you are thinking of it as a paradigm.

It wasn't a secret:

But rather obscure hidden in a ton of words.

A common criticism of Equivalence is that some people say that it does nothing to help them to take better pictures. However, Equivalence is simply a framework by which to compare the IQ of different formats on the basis of six visual properties that are independent of the technology -- the same perspective, framing, DOF / diffraction / total amount of light on the sensor, exposure time (motion blur), lightness, and display dimensions. Equivalence is not an "instruction manual" for how to take a photo, but rather a comparison point for photographs from different systems.

The description of the paradigm is rather vague, however.

Which is exactly what I said below:

Your admission of its vagueness explains why whenever Equivalence is discussed it is like the fable of the three blind men trying to describe an elephant.

I will just take that for what its worth.

.

Go back and read what I asked for.

There's your single sentence and is no more or less helpful in understanding what Equivalence is about than, say, a single sentence definition of Capitalism:

an economic system characterized by private or corporate ownership of capital goods, by investments that are determined by private decision, and by prices, production, and the distribution of goods that are determined mainly by competition in a free market

But, for those for whom the definition as given is too much to handle:

Equivalent photos are photos of a given scene that have the:

As a corollary, Equivalent lenses are lenses that produce Equivalent photos on the format they are used on which means they will have the same AOV (angle of view) and the same aperture diameter. The following rules of thumb, which are a consequence of the above definition, are also helpful to understand:

  • For a given exposure, more light is projected on a larger sensor.
  • For a given scene, DOF, and exposure time, the same amount of light is projected on all sensors, regardless of size.
  • Thus, the only way for a larger sensor to collect more light is to use a more shallow DOF or longer exposure time.

What can you do, right? It's definitely longer than a sentence or two, so I guess that limits its utility to less than 1% of the population, right?

 mamallama's gear list:mamallama's gear list
Panasonic Lumix DMC-GX85 +1 more
Great Bustard Forum Pro • Posts: 42,986
The 0.001%
1

fferreres wrote:

Probably, only 1 out of 10,000 photographers need to know of any equivalence. And 3 out 6 billion need to know about the Church of Equivalence yet in their thoughts, it should have 6 billion followers.

Same can be said about the Sun being the center of the Solar System, yet the schools teach it to everyone. I mean, for 99.999% of the people, it's enough to know the Sun "rises" and "sets" once a day and there are seasons.

But is that any reason to argue against teaching that the Earth orbits the Sun every 365.2422 days, spins around its own axis once a day, and that the 23.4° tilt of the axis results in daylight being longer and stronger in summer and shorter and weaker in winter as it orbits the Sun, resulting in the seasons?

I mean, no one needs to know that, right? And yet, it's taught to almost everyone.

Great Bustard Forum Pro • Posts: 42,986
Re: Yep, that's the modern world, all right.

mamallama wrote:

Great Bustard wrote:

mamallama wrote:

Great Bustard wrote:

mamallama wrote:

Great Bustard wrote:

mamallama wrote:

Great Bustard wrote:

mamallama wrote:

I love the clarity when just the mention of equivalence results in multiple threads that limit out at 150. A concise one sentence definition of equivalence might help the clarity.

If you can't say it all in a Twitter post, then it isn't worth saying -- that's the world we now live in. Maybe if I ask the POTUS, he can do it just for you.

Now I know why it isn't worth saying.

Well, you were the one asking for the Twitter post version to get some clarity. So the three bullet points I gave:

  • For a given exposure, more light is projected on a larger sensor.
  • For a given scene, DOF, and exposure time, the same amount of light is projected on all sensors, regardless of size.
  • Thus, the only way for a larger sensor to collect more light is to use a more shallow DOF or longer exposure time.

were too much of a chore for you -- you wanted a "concise one sentence definition of equivalence" in order to have "clarity", but now say that a one sentence definition isn't worth saying because it reflects the same mindset of someone whose politics you don't like. Oh well -- can't please them all, I suppose.

Sorry, that is not a one sentence definition.

No kidding -- I said that my three bullet points "were too much of a chore for you" because you wanted a single sentence. But when I noted that the POTUS is the king of single sentence explanations, you said, "Now I know why it isn't worth saying". But, if you must have a single sentence, here it is:

[Photographic] Equivalence is a paradigm that relates the visual properties of photos of a given scene from different formats based on perspective, framing, and the diameter of the [effective] aperture.

At least we know you are thinking of it as a paradigm.

It wasn't a secret:

A common criticism of Equivalence is that some people say that it does nothing to help them to take better pictures. However, Equivalence is simply a framework by which to compare the IQ of different formats on the basis of six visual properties that are independent of the technology -- the same perspective, framing, DOF / diffraction / total amount of light on the sensor, exposure time (motion blur), lightness, and display dimensions. Equivalence is not an "instruction manual" for how to take a photo, but rather a comparison point for photographs from different systems.

But rather obscure hidden in a ton of words.

It's the first paragraph of the "hidden" section with the title of The Purpose of Equivalence. Hide and Seek was certainly not your favorite game, I guess.

The description of the paradigm is rather vague, however.

Which is exactly what I said below:

Go back and read what I asked for.

There's your single sentence and is no more or less helpful in understanding what Equivalence is about than, say, a single sentence definition of Capitalism:

an economic system characterized by private or corporate ownership of capital goods, by investments that are determined by private decision, and by prices, production, and the distribution of goods that are determined mainly by competition in a free market

Your admission of its vagueness explains why whenever Equivalence is discussed it is like the fable of the three blind men trying to describe an elephant.

My "admission of its vagueness" was me trying (in vain) to explain to you that single sentence explanations are not always useful. Perhaps you recall me giving the example of the tweets by the POTUS to send that point home?

I will just take that for what its worth.

I'm pretty sure you won't. In any case, here it is again:

But, for those for whom the definition as given is too much to handle:

Equivalent photos are photos of a given scene that have the:

As a corollary, Equivalent lenses are lenses that produce Equivalent photos on the format they are used on which means they will have the same AOV (angle of view) and the same aperture diameter. The following rules of thumb, which are a consequence of the above definition, are also helpful to understand:

  • For a given exposure, more light is projected on a larger sensor.
  • For a given scene, DOF, and exposure time, the same amount of light is projected on all sensors, regardless of size.
  • Thus, the only way for a larger sensor to collect more light is to use a more shallow DOF or longer exposure time.

But, like I said before:

What can you do, right? It's definitely longer than a sentence or two, so I guess that limits its utility to less than 1% of the population, right?

fferreres Senior Member • Posts: 1,935
Re: Yep, that's the modern world, all right.

Great Bustard wrote:

fferreres wrote:

Great Bustard wrote:

[Photographic] Equivalence is a paradigm that relates the visual properties of photos of a given scene from different formats based on perspective, framing, and the diameter of the [effective] aperture.

...

no more or less helpful in understanding what Equivalence is about than, say, a single sentence definition of Capitalism:

an economic system characterized by private or corporate ownership of capital goods, by investments that are determined by private decision, and by prices, production, and the distribution of goods that are determined mainly by competition in a free market

I have an alternative definition:

Photographic equivalence provides some rules of thumb to assess how a shot in certain format could have been shot in a different one and still look quite the same.

I suppose your alternative definition for capitalism might go something like:

Capitalism provides some rules of thumb on how the government and people interact with regards to business transactions, how labor is compensated, and the possession of goods property.

I'd go for a definition closer to Adam Smith's words which was much more clearer and informative than the word Capitalism, which was actually coined by Marx with a pejorative way.

But to the point of photographic equivalence, for me, it is a great tool or "practice", and not a paradigm. It's more a bridge than a destination.

Bill Ferris
Bill Ferris Veteran Member • Posts: 4,197
Re: The Recent F/stop Controversy
3

Michael Fryd wrote:

Bill Ferris wrote:

Digital doesn't have the same sort of response curve. There's a wide range of exposures that produce a good quality raw file.

However, if we want to pretend that digital acts like film, we need to pretend that there is a "correct exposure". Therefore we have to pick one. Generally we say that we have "correct exposure" when the image lightness of the camera produced preview looks good.

Before going further, let's remind ourselves that the exact same factors that determine exposure for film media also determine exposure for pixel-based, light-sensitive media. Those factors work the same way. Everything from aperture diameter to zoom range applies the same for digital as it does for film.

Also, let's establish that it's in your interest to demonstrate real, tangible benefits to photographers who adopt your proposal. In the absence of any real benefits, there is no incentive to change the systematic approach to photography that has worked for generations and still works, today.

Of course, what we really are saying is that the "correct exposure" is one where the exposure is a good match for the selected ISO.

I'm going to suggest that "correct exposure" is the wrong terminology. The correct terminology is "correct ISO". With digital there is no need to set the ISO and them make the exposure match. With digital you pick aperture and shutter, and then pick the ISO that corresponds to that exposure.

In photojournalism, there used to be a popular saying, "F/8 and be there." Perhaps, some version of that is still in use? I don't know. I mention this to illustrate thay photographers have prioritized creative settings ahead of sensitivity, since long before digital was a thing. Whether shooting landscapes, portraits or news, film photographers often choose an f-stop for a desired depth of field, a shutter speed to control the appearance of motion and are constantly on the lookout for films that allow improved print quality.

Adopting your proposal does nothing to change that or to make it any easier.

So the question of whether a digital image is "properly exposed" doesn't make sense unless we pretend that digital acts like film.

In many fundamental ways, a digital camera system does act like film. Optically, the same physics applied to lenses for film cameras are applied to digital cameras. Lenses designed in the film era are still used with digital cameras. It's well-established that scene brightness, shutter speed and f-stop determine exposure, both for film and digital. There's no need to beat that drum, any more.

Film ASA and digital ISO are not the same and this has been the catalyst for many an enjoyable & entertaining discussion in these forums.

Earlier, you described digital as producing a wider range of good quality exposures. Are you sure? One of the biggest advantages of digital over film, is that every possible ISO (or ASA, if one prefers) film stock is contained within the camera. The ability to select an ISO from 100 to 100,000 (or higher) effectively makes all film ASAs available, at any time.

By contrast, a film photographer can only have one roll of film in the camera at any one time. It's one reason professional photogs started carrying more than one camera. Not only was a second body a backup, it also allowed the photographer to have a roll of color negative film in one camera and a roll of Tri-X 400 in a second body.

Film allows one to use ASAs from about 60 to 6400 to make quality exposures and prints. That's at least a seven stop range. Film is inherently better than digital at preserving and allowing recovery of detail in highlights. That's another few stops, at least. Digital has an inherent advantage at recovering detail in shadows so, one can use ISOs higher than 6400; in some cases much higher.

Ultimately, both media offer a wide latitude of usable exposures. In both media, the same settings and controls for exposure can be applied to make great images.

Again, we return to the fundamental question of what real-world benefits await those who adopt the change you propose? What photograph will I be able to make that I'm not presently able to make? What task becomes significantly easier?

Suppose I have a full frame camera, and I am getting a perfect image shooting a 50mm lens at f/4, 1/60 and ISO 400.

The camera breaks, and I put out my 2X crop body to continue shooting. Why would I want to match the full frame exposure (light per unit area) on the 2X crop body?

If the photo you're making doesn't suffer from f/4, 1/60, ISO 400, those settings will deliver a good exposure and a good image. If you desire a certain depth of field or wish to use a shutter speed that freezes motion to a certain degree, use the settings that will deliver the image you desire with the equipment you're using.

This is all totally achievable, today, without adopting the change you propose.

If I was shooting film, matching the exposure is critical. If I don't I won't have a useable negative.

If your backup film body is loaded with ASA 1600 film, which exposure settings would you use?

If I am shooting digital, matching the exposure will give me different results. At the same exposure, the 2X crop body will give me a noisier result. At the same f/stop, the 2X crop body will also give me deeper depth of field, and more diffraction blur.

What real world differences are we talking about, here? If your crop body can't make clean images at ISO 400, maybe you should replace it. If the diffraction effects of your lens are unacceptable at f/4, you should definitely replace it.

If I am not shooting film, why would I want to keep the same exposure on my backup camera? Why not use the exposure that gives me the same results? (which will be an exposure that has the same total light, and same aperture diameter).

What if that's not possible? If you only have the f/4 lens and it doesn't open to f/2, what would you do? My guess is thay you'd find a way to make a good photo. It wouldn't be equivalent to the image you were going to make with the other camera but, frankly, that's only a minor detail. I shoot with full-frame, APS-C and smartphone systems, not because they're equivalent, but precisely because they are different. And some of those differences translate to advantages.

Well, we started with the question should we get rid of the f/stop. I think there is a good case to be made the we should deemphasize that terminology and emphasize aperture diameter instead.

Digital cameras have a lots of computational power and sophisticated displays. I think camera firmware should be helpful enough to display the aperture diameter.

The creative advantage is that it reduces the amount of mental calculations one needs to do.

I can honestly say I've never had to calculate the aperture diameter of a lens to achieve a photograph I wanted to make. I suspect the same can be said of most photographers. For me and others, a camera that calculates and displays a setting I never use offers no advantage over a camera that does not calculate and display the same setting.

Assume you move closer to your subject and change the focal length to maintain the same framing. If the aperture diameter remains the

That is incorrect. If you move nearer the subject while maintaining the same aperture diameter and angle of view, apparent depth of field will be reduced. It will be shallower. Here, are two photos illustrating this:

Photo 1: 55mm, f/6.4, distance to subject is 4-feet, aperture diameter is 8.6mm

Photo 2: 27.7mm, f/3.2, distance to subject is 2-feet, aperture diameter is 8. 6mm

Notice the out of focus appearance of the trophy and tiles above the fireplace. The depth of field appears shallower due to the background elements looking obviously softer in focus. This change in appearance is due to the same approximately 8.6mm aperture diameter being used to photograph the background elements from a nearer distance.

By the way, I erred earlier when I said I've never calculated an aperture diameter to make a photo. I calculated the aperture diameters used for these photos.

We are able top make decisions about acceptable shot noise, now, using scene brightness, shutter speed and f-stop to control exposure, and ISO as an indicator of acceptable exposure.

Not really. That's not enough information. You don't have enough information to determine total light captured, so you can't predict how noisy the image will be.

While digital cameras come with an almost inexhaustible supply of ISOs they come with just one sensor. Once you're committed to using a camera, there is no option to select a larger sensor. As we know, maximizing exposure for a scene also maximizes the volume of light which can be captured in a single exposure of that scene.

As I wrote in the previous reply, seeing and making a rough evaluation of scene brightness goes a long way toward informing the choices of f-stop and shutter speed made by a photographer. An experienced photographer will notice a change to the quality of light and adjust f-stop or shutter speed - almost instinctively - to preserve a desired exposure. This happens every day, thousands of times a day all over the world.

And if you're genuinely concerned about not capturing enough light from any area of the composition in a single exposure, there is sometimes the option of making and combining multiple exposures into a single image.

There is no need to calculate a specific amount of noise. There is only the need to know how to use shutter speed and f-stop to control exposure, the ability to interpret a histogram and a willingness to look at a photograph I've made and say, "Not good enough. I need to increase exposure to reduce noise."

ISO 400, f/4, 1/60 might result in a noisy image if you are using a smart phone, and a clean image of you are using full frame.

If your smartphone doesn't make an acceptable photograph of a scene at those settings, use different settings or a different camera.

Exposure alone (light per unit area) is not enough to determine shot noise. You need to know the sensor area so you can consider total light captured.

Exposure, alone, is enough to determine of you're capturing as much light as possible from a scene within the constraints of your chosen creative settings constraints. If the shot noise is objectionable, use a different camera with a larger sensor or make a different photo.

Photographers already control depth of field using focal length, f-stop and distance to subject.

Not really. you need to add sensor size in there or you can't determine depth of field. You need to know the sensor size you you can convert f/stop to aperture diameter and the figure out the angle of view.

I don't calculate the actual depth of field because that information is not needed to make a good photo. All I need to know is that changing the distance to the subject (while keeping focal length and f-stop constant) changes depth of field. Being nearer produces a shallower depth of field and being more distant creates a deeper depth of field. Alternatively, I can maintain subject distance & footbal length and adjust f-stop (smaller/faster = shallower, larger/slower = deeper) to control depth of field.

I can rely on my experience as a photographer to make adjustments for the various subjects, backgrounds and lighting situations I encounter. There's also the option of choosing a different perspective offering a more pleasing background.

Individually none of these tell us the whole story. Yet if we know these we can predict the results without knowing sensor size or focal length.

We're already able to predict the results without giving aperture diameter or total light captured any consideration.

Only because you are using formula that take total light and aperture diameter into consideration. If you don't have enough information to determine diameter and total light, then you don't have enough information.

On this point, I and the vast majority of photographers will respectfully disagree. We don't calculate aperture diameter or the total light captured. Not having this information does nothing to limit our ability to make good photographs.

Benefits include:

  • The explanation of how things work is simpler. It leaves out implementation details that are not important to the result.

You've demonstrated neither.

  • It moves mental models away from exposure being paramount, and onto a more equal footing for shutter speed and aperture.

Light, is the priority. In the absence of light, all else is irrelevant.

  • it is independent of sensor size, which makes it easier to teach or discuss amongst people who may be using different sensor sizes.

Exposure is independent of sensor size. Total light captured is dependent on sensor size.

Michael, if the change you propose had real potential to deliver tangible benefits to photographers, I'd be standing shoulder-to- shoulder with you advocating for change. However, you've not made a persuasive case for any benefit from this change. From where I stand, it appears to be change for change's sake.

Clearly, you believe this change is needed. I would encourage you to dig deep in search of a real, tangible benefit. If you can demonstrate that adopting this perspective will make some type of photography either doable or much easier, others will come on board. But if it remains essentially a battle of archaic concepts, nobody's gonna get on your bandwagon.

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Bill Ferris Photography
Flagstaff, AZ
http://www.billferris.photoshelter.com

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