Alternative term for "exposure triangle"?

D Cox said:

over exposed seahorse said:

Why does it need renaming at all? Atleast two thirds (the shutter speed and the aperture) do indeed affect the exposure (in its true meaning), and the shape of the triangle makes sense, if it is drawn correctly (see below).

Click to expand...

Suppose you have a film or an ISO-less camera that is always at 200, and an f/2.8 lens.

So far as I can read this diagram, that means you can only shoot at f/2.8, which is certainly not the case.

Indeed, the more I look at this admittedly elegant diagram, the less it makes sense.

Click to expand...

D Cox said:

over exposed seahorse said:

Why does it need renaming at all? Atleast two thirds (the shutter speed and the aperture) do indeed affect the exposure (in its true meaning), and the shape of the triangle makes sense, if it is drawn correctly (see below).

Click to expand...

Suppose you have a film or an ISO-less camera that is always at 200, and an f/2.8 lens.

So far as I can read this diagram, that means you can only shoot at f/2.8, which is certainly not the case.

Indeed, the more I look at this admittedly elegant diagram, the less it makes sense.

Click to expand...

Christof21 said:

Exposure is 2 parameters, brightness includes pp...

Click to expand...

Member said:

There is really a missing term.

I propose "intensity". This is a kind of intensity per pixel. In physics, this is power per unit area. The power part could be discussed but here the unit area would be pixel.

Click to expand...

D Cox said:

Snow Crow said:

So... why do we need an alternative term for "exposure triangle"?! What am I missing here?

Click to expand...

Because a triangle is a plane figure, and there are at least three independent variables involved, so you need a three-dimensional figure.

Click to expand...

over exposed seahorse said:

D Cox said:

over exposed seahorse said:

Why does it need renaming at all? Atleast two thirds (the shutter speed and the aperture) do indeed affect the exposure (in its true meaning), and the shape of the triangle makes sense, if it is drawn correctly (see below).

Click to expand...

Suppose you have a film or an ISO-less camera that is always at 200, and an f/2.8 lens.

So far as I can read this diagram, that means you can only shoot at f/2.8, which is certainly not the case.

Indeed, the more I look at this admittedly elegant diagram, the less it makes sense.

Click to expand...

I'm sorry guys, it makes perfect sense to me.
1. definition of exposure: Total amount of light reaching the sensor (only a factor of shutter and aperture)

Take one of the horizontal aperture lines, and look to see where your green shutter speed line intersects it. This is the exposure youre interested in. Take a note of the iso line at that intersection point. Now to keep the exposure the same, youre just sticking on that same blue iso line, but can choose any intersecting combination of shutter and aperture => this will give the same exposure (amount of light reaching the sensor) as your original combination.

2. definition of exposure: Brightness of the resulting image (using aperture, shutter and iso).

Say youre exposing correctly at that dot (iso 1600, f2.8, 1/30 s). You want to change some/all of these to achieve the same brightness image. So like above, you can move up and down your iso line, which will change both the apeture and the shutter speed. You can move up and down the diagonal green line, which will keep the shutter speed the same, but change the iso and aperture, or you can move along the horizontal red line, which will keep the aperture the same, but change the shutter speed and the iso. Or you can do a combination of all:

From the dot, move the iso to 3200, keeping the aperture the same, we can see our correct exposure is not iso 3200, 1/60 sec, f2.8. Now from that point there, change the aperture to f5.6 We end up at 1/15 sec, f5.6, iso 3200. This is exactly the same exposure we started off with

Click to expand...

Christof21 said:

It is amplification (digital ot analog)..

Click to expand...

bobn2 said:

Christof21 said:

It is amplification (digital ot analog)..

Click to expand...

What is being 'amplified'?

--
Tinkety tonk old fruit, & down with the Nazis!
Bob

Click to expand...

Christof21 said:

bobn2 said:

Christof21 said:

It is amplification (digital ot analog)..

Click to expand...

What is being 'amplified'?

Click to expand...

Click to expand...

TravisDog said:

Given the extensive coverage of the concept of exposure on these forums, I suspect that we are all reasonably well versed in the term's correct definition. The trouble is students tend to find the concept of the "exposure" triangle (when applied to the overall brightness of the final image) to be quite a useful concept.

Can anybody suggest an alternative name for the exposure triangle that would be technically acceptable and doesn't sound too ridiculous?

Click to expand...

bobn2 said:

over exposed seahorse said:

D Cox said:

over exposed seahorse said:

Why does it need renaming at all? Atleast two thirds (the shutter speed and the aperture) do indeed affect the exposure (in its true meaning), and the shape of the triangle makes sense, if it is drawn correctly (see below).

Click to expand...

Suppose you have a film or an ISO-less camera that is always at 200, and an f/2.8 lens.

So far as I can read this diagram, that means you can only shoot at f/2.8, which is certainly not the case.

Indeed, the more I look at this admittedly elegant diagram, the less it makes sense.

Click to expand...

I'm sorry guys, it makes perfect sense to me.
1. definition of exposure: Total amount of light reaching the sensor (only a factor of shutter and aperture)

Take one of the horizontal aperture lines, and look to see where your green shutter speed line intersects it. This is the exposure youre interested in. Take a note of the iso line at that intersection point. Now to keep the exposure the same, youre just sticking on that same blue iso line, but can choose any intersecting combination of shutter and aperture => this will give the same exposure (amount of light reaching the sensor) as your original combination.

2. definition of exposure: Brightness of the resulting image (using aperture, shutter and iso).

Say youre exposing correctly at that dot (iso 1600, f2.8, 1/30 s). You want to change some/all of these to achieve the same brightness image. So like above, you can move up and down your iso line, which will change both the apeture and the shutter speed. You can move up and down the diagonal green line, which will keep the shutter speed the same, but change the iso and aperture, or you can move along the horizontal red line, which will keep the aperture the same, but change the shutter speed and the iso. Or you can do a combination of all:

From the dot, move the iso to 3200, keeping the aperture the same, we can see our correct exposure is not iso 3200, 1/60 sec, f2.8. Now from that point there, change the aperture to f5.6 We end up at 1/15 sec, f5.6, iso 3200. This is exactly the same exposure we started off with

Click to expand...

So, this triangle suggests that if we set, say, 400 ISO, we can only use f/1.4 at 1/30 second, f/2 at 1/15 second or f/2.8 at 1/8 second. I seem to remember having used 400 ISO with a lot of other combinations of f-number and shutter than that. Do you think that there might be something missing here?

--
Tinkety tonk old fruit, & down with the Nazis!
Bob

Click to expand...

bobn2 said:

Christof21 said:

Exposure is 2 parameters, brightness includes pp...

Click to expand...

Just 'p'. You need to process the image, no need to do anything after.

bobn2 said:

There is really a missing term.

I propose "intensity". This is a kind of intensity per pixel. In physics, this is power per unit area. The power part could be discussed but here the unit area would be pixel.

Click to expand...

Actually, still based on a misconception. What you get in a photo isn't 'intensity' or 'power'. What it is technically is 'lightness' (the 'L' in Lab colour space). It's not intensity or power because that depends on how you view the photo. For instance, if it's a print the 'lightness' is realised by ink of a particular shade (and the 'intensity' of the ink is in reverse to the 'intensity' of the light that made the photo). Likewise, if it's and LCD screen, it governs an LCD shutter, and the more 'intense' the effect of the shutter the less of the backlight shines through.

It's this erroneous idea that a photo is both 'light in' and 'light out' that leads to many of the misconceptions that surround the triangle, not least that something has to be 'amplified' if you want to get a photo from less light.

Click to expand...

Anthelix said:

The exposure triangle as a ternary plot https://en.m.wikipedia.org/wiki/Ternary_plot, perfectly shows the interdependence between three parameters. However, it might be a bit overkill for a photography course. (What about faucet and kitchen sink metaphers ?)

What is controversial is the choice of the three parameters. I personnally think it is a mistake to establish a symetry between aperture, exposure time and amplification. For me, the exposure triangle should be built arround aperture, exposure time and luminance. Amplification should be treated as a separate parameter.

Click to expand...

D Cox said:

Snow Crow said:

So... why do we need an alternative term for "exposure triangle"?! What am I missing here?

Click to expand...

Because a triangle is a plane figure, and there are at least three independent variables involved, so you need a three-dimensional figure.

Much the same applies to colour. In the early days, people thought of colour as a 2-dimensional circle, but nowadays we talk about colour solids with (at least) three dimensions.

Click to expand...

Porky89 said:

bobn2 said:

Christof21 said:

Exposure is 2 parameters, brightness includes pp...

Click to expand...

Just 'p'. You need to process the image, no need to do anything after.

Porky89 said:

There is really a missing term.

I propose "intensity". This is a kind of intensity per pixel. In physics, this is power per unit area. The power part could be discussed but here the unit area would be pixel.

Click to expand...

Actually, still based on a misconception. What you get in a photo isn't 'intensity' or 'power'. What it is technically is 'lightness' (the 'L' in Lab colour space). It's not intensity or power because that depends on how you view the photo. For instance, if it's a print the 'lightness' is realised by ink of a particular shade (and the 'intensity' of the ink is in reverse to the 'intensity' of the light that made the photo). Likewise, if it's and LCD screen, it governs an LCD shutter, and the more 'intense' the effect of the shutter the less of the backlight shines through.

It's this erroneous idea that a photo is both 'light in' and 'light out' that leads to many of the misconceptions that surround the triangle, not least that something has to be 'amplified' if you want to get a photo from less light.

Click to expand...

Click to expand...

J A C S said:

Here is a better exposure "triangle":

https://en.wikipedia.org/wiki/Exposure_value

Wait, no ISO??? ;-)

Popular exposure chart type, showing exposure values EV (red lines) as combinations of aperture and shutter speed values. The green lines are sample program lines, by which a digital camera automatically selects both the shutter speed and the aperture for given exposure value (brightness of light), when set to Program mode (P). (Canon, n.d.)

Click to expand...

Porky89 said:

bobn2 said:

over exposed seahorse said:

D Cox said:

over exposed seahorse said:

Why does it need renaming at all? Atleast two thirds (the shutter speed and the aperture) do indeed affect the exposure (in its true meaning), and the shape of the triangle makes sense, if it is drawn correctly (see below).

Click to expand...

Suppose you have a film or an ISO-less camera that is always at 200, and an f/2.8 lens.

So far as I can read this diagram, that means you can only shoot at f/2.8, which is certainly not the case.

Indeed, the more I look at this admittedly elegant diagram, the less it makes sense.

Click to expand...

I'm sorry guys, it makes perfect sense to me.
1. definition of exposure: Total amount of light reaching the sensor (only a factor of shutter and aperture)

Take one of the horizontal aperture lines, and look to see where your green shutter speed line intersects it. This is the exposure youre interested in. Take a note of the iso line at that intersection point. Now to keep the exposure the same, youre just sticking on that same blue iso line, but can choose any intersecting combination of shutter and aperture => this will give the same exposure (amount of light reaching the sensor) as your original combination.

2. definition of exposure: Brightness of the resulting image (using aperture, shutter and iso).

Say youre exposing correctly at that dot (iso 1600, f2.8, 1/30 s). You want to change some/all of these to achieve the same brightness image. So like above, you can move up and down your iso line, which will change both the apeture and the shutter speed. You can move up and down the diagonal green line, which will keep the shutter speed the same, but change the iso and aperture, or you can move along the horizontal red line, which will keep the aperture the same, but change the shutter speed and the iso. Or you can do a combination of all:

From the dot, move the iso to 3200, keeping the aperture the same, we can see our correct exposure is not iso 3200, 1/60 sec, f2.8. Now from that point there, change the aperture to f5.6 We end up at 1/15 sec, f5.6, iso 3200. This is exactly the same exposure we started off with

Click to expand...

So, this triangle suggests that if we set, say, 400 ISO, we can only use f/1.4 at 1/30 second, f/2 at 1/15 second or f/2.8 at 1/8 second. I seem to remember having used 400 ISO with a lot of other combinations of f-number and shutter than that. Do you think that there might be something missing here?

--
Tinkety tonk old fruit, & down with the Nazis!
Bob

Click to expand...

For a given light intensity.

Click to expand...

Porky89 said:

It isn't exactly rocket science, is it? Why must you always complicate things? Or are you really that dumb?

Click to expand...

Porky89 said:

Photographers have been using the exposure triangle for 150 years and will be using it long after you an I are gone. Deal with it.

Click to expand...

bobn2 said:

Porky89 said:

bobn2 said:

over exposed seahorse said:

D Cox said:

over exposed seahorse said:

Why does it need renaming at all? Atleast two thirds (the shutter speed and the aperture) do indeed affect the exposure (in its true meaning), and the shape of the triangle makes sense, if it is drawn correctly (see below).

Click to expand...

Suppose you have a film or an ISO-less camera that is always at 200, and an f/2.8 lens.

So far as I can read this diagram, that means you can only shoot at f/2.8, which is certainly not the case.

Indeed, the more I look at this admittedly elegant diagram, the less it makes sense.

Click to expand...

I'm sorry guys, it makes perfect sense to me.
1. definition of exposure: Total amount of light reaching the sensor (only a factor of shutter and aperture)

Take one of the horizontal aperture lines, and look to see where your green shutter speed line intersects it. This is the exposure youre interested in. Take a note of the iso line at that intersection point. Now to keep the exposure the same, youre just sticking on that same blue iso line, but can choose any intersecting combination of shutter and aperture => this will give the same exposure (amount of light reaching the sensor) as your original combination.

2. definition of exposure: Brightness of the resulting image (using aperture, shutter and iso).

Say youre exposing correctly at that dot (iso 1600, f2.8, 1/30 s). You want to change some/all of these to achieve the same brightness image. So like above, you can move up and down your iso line, which will change both the apeture and the shutter speed. You can move up and down the diagonal green line, which will keep the shutter speed the same, but change the iso and aperture, or you can move along the horizontal red line, which will keep the aperture the same, but change the shutter speed and the iso. Or you can do a combination of all:

From the dot, move the iso to 3200, keeping the aperture the same, we can see our correct exposure is not iso 3200, 1/60 sec, f2.8. Now from that point there, change the aperture to f5.6 We end up at 1/15 sec, f5.6, iso 3200. This is exactly the same exposure we started off with

Click to expand...

So, this triangle suggests that if we set, say, 400 ISO, we can only use f/1.4 at 1/30 second, f/2 at 1/15 second or f/2.8 at 1/8 second. I seem to remember having used 400 ISO with a lot of other combinations of f-number and shutter than that. Do you think that there might be something missing here?

--
Tinkety tonk old fruit, & down with the Nazis!
Bob

Click to expand...

For a given light intensity.

Click to expand...

Rather for a specific light intensity.

Click to expand...

bobn2 said:

J A C S said:

Here is a better exposure "triangle":

https://en.wikipedia.org/wiki/Exposure_value

Wait, no ISO??? ;-)

Popular exposure chart type, showing exposure values EV (red lines) as combinations of aperture and shutter speed values. The green lines are sample program lines, by which a digital camera automatically selects both the shutter speed and the aperture for given exposure value (brightness of light), when set to Program mode (P). (Canon, n.d.)

Click to expand...

'Exposure Value' isn't 'brightness of light. As you correctly say above, it is the combination of f-number and shutter. The confusion is cause because flash and AF specs measure brightness of light in EV₁₀₀, which is the brightness of light where the given EV value gives nominal exposure at 100ISO. Unfortunately the subscript '100' usually gets left off, leading people to thing that 'EV' describes the brightness of light.

Like the dreaded 'triangle' your diagram omits the brightness of the light.

Click to expand...

J A C S said:

bobn2 said:

J A C S said:

Here is a better exposure "triangle":

https://en.wikipedia.org/wiki/Exposure_value

Wait, no ISO??? ;-)

Popular exposure chart type, showing exposure values EV (red lines) as combinations of aperture and shutter speed values. The green lines are sample program lines, by which a digital camera automatically selects both the shutter speed and the aperture for given exposure value (brightness of light), when set to Program mode (P). (Canon, n.d.)

Click to expand...

'Exposure Value' isn't 'brightness of light. As you correctly say above, it is the combination of f-number and shutter. The confusion is cause because flash and AF specs measure brightness of light in EV₁₀₀, which is the brightness of light where the given EV value gives nominal exposure at 100ISO. Unfortunately the subscript '100' usually gets left off, leading people to thing that 'EV' describes the brightness of light.

Like the dreaded 'triangle' your diagram omits the brightness of the light.

Click to expand...

So it is a triangle after all? ;-)

Click to expand...

J A C S said:

Yes, EV is a relative measure of exposure (for a fixed scene luminance); the actual exposure needs to include the scene luminance. If we start digging deeper, we will discover that the light varies across the scene and across the frame, so we may have to include the position, and that adds two more variables to the three we have already.

Click to expand...