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Can We Just Kill the Exposure Triangle Already?

The exposure triangle claims to explain the relationship between shutter speed, aperture, and ISO. At first glance, it looks like a useful diagram, until you realize that it’s not all what it's cracked up to be.

It's Pretty, but Not Accurate

When you first see the Exposure Triangle it’s an attractive graphical chart or diagram showing the range of each setting and the effect each setting has upon the exposure. That’s where the usefulness ends. Then newcomers start asking about where the current exposure is indicated in the triangle, only to find out it's not.

WClarke, Wikimedia, CC BY-SA 4.0

The triangle indicates that if you go up in ISO you brighten the image, but as you do you get closer to the corner that also indicates more depth of field and a darker image. This is where it all falls apart.

Placing the elements of exposure in a graphical representation of a triangle implies that there is a relationship between each side and/or the corners. That's the whole purpose of a diagram like this, to depict the relationship between items. The Exposure Triangle does nothing to explain the relationship between these items. It simply takes three things and puts them in a triangle.

The current exposure is not represented in the triangle. When one setting changes it doesn’t explain how you can change either of the other two settings to maintain the proper exposure.

I'm very technical; I'm a software developer. I've written code to make charts and graphs to graphically represent data. When I first saw the Exposure Triangle I stared at it for a little while trying to figure out how the sides interacted with each other. After a while of analyzing it, I realized that they were not related in any way and it was simply three settings placed in a triangle for no other reason than a triangle has three sides.

A Better Diagram

I'm not saying that this is the best that it gets, but I think the following image does a little better job at describing what will happen when you change a setting:

In fact, it’s easier to explain that for a given exposure, using the above chart, that if you go darker on one setting you can simply go brighter on another setting the same number of stops to maintain that exposure. This is because each stop either lets in (exposes for) half as much or twice as much light as the previous stop. That’s it. Half as much, twice as much. As for ISO, it doesn't let in more or less light, but it does allow for the changing of shutter speed and aperture, which does.

ISO Isn't Part of Exposure

Exposure is the amount of light falling per unit area on the sensor. Technically ISO isn't a component of the exposure. It's simply amplifying the sensor values and modifying the captured image so that it will appear the "same" as it would have if the image had been properly exposed at ISO 100 (or whatever the base ISO of the sensor is). It's similar to the volume on a radio, the incoming signal doesn't get any stronger, it's just being played louder (amplified), static and all. But since sensitivity is simulated on digital cameras (as apposed to actual sensitivity of film), we'll pretend it's part of the exposure since it's what we work with when taking a photo.

The Myth Will Live On

I don’t think the Exposure Triangle is ever going away. It’s like the myth that swimming after eating will give you cramps. It’s been debunked a million times, yet the myth still lives on. In fact, my grandkids just repeated it to me the other day.

It’s only THREE THINGS. Each only has one primary attribute. Whatever happened to “It’s easy as 1-2-3”? So what should we call it? The Exposure Triad? The Three Pillars of Exposure? The Exposure Trinity?

How about just the three primary settings of exposure? What is your opinion of the Exposure Triangle?

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124 Comments

Eric Salas's picture

I find that teaching people to view it like a skills graph enables them to apply how the triangle is IMO very useful for beginners.

Michael Rapp's picture

While I'm the first to hop on the good visualization train. the trianglular shape of the ET only shows that there are three factors to the exposure (leaving ISO in there, for argumetn's sake)
Yet, like in the example you provide, it does do nothing to show HOW these values are related to EACH OTHER!
Although, if you really want to geek out and set the units along the ET accordingly, the surface area of the ET should remain constant for a consistent exposure.
But good luck working out the details. It can be done, but not with linear scales. And avoiding the cornerpoints, too. :-)

Eric Salas's picture

I’m not working out the details of it, only providing a visualization. Education can be accomplished many ways and everyone learns differently.
Only the student grasping the knowledge matters not your view on if it works or not.

That goes back to the author of this article; if the triangle doesn’t do it for you, then move on. People overcomplicate simple things and ruin the chance of learning development by being narrow minded.

Black Z Eddie .'s picture

I never did get the exposure triangle. Hell, to this day. When I think exposure triangle, it just means 3 settings.

Funny, similar with your diagram, when I was first learning, that's how I figured out what the shutter speed and aperture do. I primary adjusted the shutter speed. Turning the dial to the left = brighter. Turning to the right = darker. Eventually, it stuck to my head since I can see the numbers change.

Lenzy Ruffin's picture

Had never seen it as an actual triangle before this. When I got started, I learned the relationships, but I didn’t know it could be drawn in a diagram. I just took it as the three things that needed to be balanced to achieve proper exposure.

I don’t think the triangle is harmful. If I’d seen it graphically back when I got started, I don’t think it would have slowed my understanding and it might have accelerated it.

Jerome Brill's picture

You have a single answer "exposure" the general brightness and darkness of an image. It's not a math problem, it's a visual one. As a visual person I understand that the triangle only exists because there are three options. Using a line to represent each option allows you to connect those into a triangle. Who ever created it, could have used that artistically, or that is represents a single answer, probably both. Each connected point of the triangle doesn't actually mean anything, it's moot. Only that each side of the triangle represents a single value that affects the total exposure.

Regardless, everything about it is true, It just doesn't give a straight answer on the actual exposure when it says one option makes something darker and another brightens it up. Both are true at the same time. Grasping this is just a part of photography no matter how simple the diagram. Understanding a triumvirate problem doesn't change.

michaeljin's picture

It's a triangle because of the simple geometric properties of a triangle—there are three angles and they must add up to 180 degrees (assuming we're not delving into non-Euclidean geometry)... Like the corners of a triangle, you're dealing with 3 values (Aperture, Shutter Speed, ISO) when you expose an image where the final value is determined by the other two to arrive at the "correct" result.

Obviously it's a rudimentary tool and it might lead some to mistakenly assume that there is a singular "correct" exposure, but it's design is primarily to illustrate that the three variables are interconnected. If you change the value of one angle in a triangle, you need to change one or both of the other angles to compensate and still preserve the triangle shape. If you change the value of one of the variables of exposure, then you need to similarly compensate for that change across either one or both of the other variables to preserve the same exposure. It's no different from the similar "Quality, Speed, Cost" triangle that's often used to broadly demonstrate the relationships between those things as it applies to work.

I don't get why this needs to be rocket science. It works and it makes perfect sense. BTW, I've never seen the actual values of the exposure triangle written out like that graphic. That's just plain stupid.

Alec Kinnear's picture

Thanks for the straight shooting, Michael. The article is just more clickbait claptrap. I do sympathise with the editors. Imagine having to populate a photography website with five new articles/day. Imagine having to draw a certain number of opens per article. This is the result.

Not making us better photographers, not making us more thoughtful people. Sadly.

Rashad Hurani's picture

Now everyone hates Expo Triangle! But I like it, some result depends on 3 things to get done properly, why not be called a triangle? good name in my opinion

Mike Dixon's picture

Because it's not a triangle. The triangle shape doesn't add any insight into the relationship between the exposure elements. There are many things that come in threes, but you don't see them grouped into a triangle.

Jon G's picture

Arranging these three parameters in a triangle always bothered me too. But then, I'm also a software developer. Your diagram is definitely better, except that I'd put aperture on top since light passes through the aperture first, then the shutter, before the signal is finally amplified by the sensor circuitry. I also wish still camera manufacturers would stop using ISO altogether – which is not at all standardized and makes it difficult to compare noise performance across cameras. On modern digital cameras, we should really talk about gain, as you point out.

Michael Rapp's picture

To get it into a form that makes sense, it would have to be a cube. Like a brick. Lenght x width x height gets you the right exposure, if you halve one side you'd have to double any ONE of the other sides for the same volume.
Length can be Shutter speed, working fine, height can be ISO. Numbers can be taken straight, although I appreciate the fact that the thingy now rather looks like a shingle than a brick or a cube.
For the apperture, we'd need to apply a sleigh of hand, mathematically: Ignore the "f/..." stuff, take the straigt number like 2.8, 4, 5.6, 8, 11 and so on, but we need to multiply these with 1,41 (spare root of 2) to maintain the constant volume. But then, the visual representation should work.

Mike Shwarts's picture

I'm with Lenzy Ruffin and Michael Jin on this. I started in the 70s and the triangle was explained back then as three interrelated factors. If one factor changes and you wish to keep the same exposure, one or both of the other factors must compensate. In all my years, I've never seen labels like you have.

In drawing the triangle and labeling it as you have, you have created a straw man. A false point of view you can knock down.

Mike Dixon's picture

I didn't create that triangle. There are others like it widely across the web labeled just like that. Just google "exposure triangle" and then click "images" and you'll get 100's of them, it's not a new thing.

adrien willmott's picture

"then click "images"". And there is the crux of the problem.. and the solution simply is Don't click images, just type in exposure triangle explanation instead...

Mike Shwarts's picture

You have point, but people new to photography won't know to avoid misleading graphics and stick to verbal explanations.

Gary Gray's picture

The exposure triangle is nothing more than a algebraic equation utilizing logarithms, simplified, as all algebra equations tend to be. Show me the mathematical equation that makes this more simple. I don't see it.

The problem with this theory is that it complicates the problem by adding more variables to the same solution.

Depth of field has nothing to do with exposure from a mathematical perspective. Depth of field is a different equation for a different issue.

Camera manufacturers have already figured this out, what, some 150 years ago. That's why they use the exposure triangle for setting exposure.

Mr Hogwallop's picture

I thought I understood the exposure triangle until read this article...

Ryan Davis's picture

^^this

Ikaika Arnado's picture

It's actually an exposure square when you add in lighting...

Brook Brown's picture

When you add lighting you have two exposures, each with their own triangle...

Kirk Darling's picture

I've been shooting for fifty years--I was even a Zone System enthusiast, and I had never heard of an "exposure triangle" until about three years ago.

So I'd agree it's not necessary.

I think what helped us years ago (and slows down newbies) is that on mechanical cameras we had the full aperture and shutter speed scales (and often the ASA scale) right there in front of us all the time.

John Hess's picture

I read somewhere that the exposure triangle is a pretty modern invention - maybe 60s or so. I'm not entirely sure of the origin but considering photography principles go back almost to the beginning of the 19th century, it is fairly modern and flawed.

Kirk Darling's picture

I never heard anyone talking about a "triangle" in the 60s. I was a Zonie (Adams, Weston, Picker), read Feininger's books, everything Kodak was putting out. Nobody was talking about a triangle.

The reason, I think, the concept of a "triangle" didn't even surface was, first, because in a given shooting situation, there was not a film speed "scale"--film speed in a given shooting situation was a constant. It would have been possible for a sheet film users to have multiple film speeds loaded into film holders, or for a medium format user to have films of multiple speeds loaded into backs, but who did that regularly? Usually the choice of a film involved more factors than its speed, and that choice was made up front.

Second, shutter speeds and lens apertures were usually presented on cameras and lenses as physical scales right in front of the photographer.

Since the triangle is a relatively new thing (I'll bet there are no examples of it earlier than the Canon D30), sure, it can be disposed of.

I like the idea of simply adding ISO as another scale below shutter speed and aperture. I've got an old Konica medium format press rangefinder camera that has shutter speed and aperture rings on the lens barrel exactly like that. It was easy as pie to understand the relationship between them.

Of course, there are also interactive online guides that show the effect of changing the relationships in real-time.

And, dang--it's a digital camera, for crying out loud. It's not as though we have to wait to develop film to see the results of setting changes.

Just go out and do it.

John Hess's picture

Well just because you never heard of it in the 60's doesn't mean it doesn't come from that era... We didn't have the internet to spread it back then. I did read something that the first time someone came into it was a book "on Exposure" circa 1990... Perhaps 90s or earlier... It's hard to track these things.

Kirk Darling's picture

I provided a number of extant tomes on exposure from the 60s. None of the Zone System patriarchs used it an "exposure triangle." Kodak didn't use it. So who did? And I explained a reason why they wouldn't have: Because film speed was not a variable for exposure determination.

If you're going to make a counter assertion, then provide some evidence.

Bob Jetter's picture

Same here. I started back in the mid sixties. First heard of the triangle a few years back and thought it to be silly. I still pre-visualize zones and love the simplicity of Processing in Photoshop.

Timothy Roper's picture

Same here, except I just heard about this "exposure triangle" right now! I don't have an opinion on it, as it looks rather confusing and I have no use for it. But I do use a digital light meter, which automatically changes things for you, when you adjust one of the three. Also, I think old Hassled lenses (and maybe other leaf shutters, too) have a feature whereby you can "lock" the EV, so a change in aperture results in a corresponding change to shutter speed (and vice versa). No need to consult a magic triangle.

John Hess's picture

Glad to see I'm not alone in my frustration with the triangle. People that say it's "Just a learning aid" don't realize the endless debates this triangle has caused because people continue to take it way too literally. Here's my (motion photography) take on why I posted a few days ago and there's a lot of similar conclusions:

https://youtu.be/R7edYQk_4ao

Mike Dixon's picture

I just watched that video when my article was waiting to go out. Your videos are always so nicely done.

Jim Tincher's picture

ISO isn't part of the exposure? Seriously?

The triangle is simply a way to show a relationship between the three elements that determine exposure. It's not that complicated.

cliff curtis's picture

Maybe I'm over complicating this, but exposure seems to me the amount of light that the sensor (or film) is being exposed to. Once the sensor has been exposed then the camera adjusts the amplification (iso). In the case of film, the amplification is pre set. Like the comment earlier, I would have to make the case that external lighting could have a more logical place in exposure than ISO. (Not saying I'm right, just a thought).

cliff curtis's picture

As a relative beginner to photography (several years of editing, just one of shooting), I will have to say the triangle was more complicated than it needed to be. In the beginning it is much better to keep things simple, ie the graph added in the article. When I taught my wife the basics she didn't get it until I just simply said "these two allow more light in and this one just amplifies the light you have". After she understood that, we moved on to depth and motion blur. With a triangle I feel like the goal would be to find the balance between the 3. Personally, I choose to get the first two right, and only then, turn up the ISO if it's absolutely necessary. Is there a reason not to do this?

Point being, the triangle did nothing for us except make photography seem like a cool club that was too complicated for the rest of us commoners.

Guy Incognito's picture

I taught myself in a similar way.. For me, I just thought "aperture is the amount of light let through, shutter is the duration that amount of light is let through, & ISO is the amplification of the two with a penalty of noise in the resulting exposure."

The triangle did nothing for me but I was able to avoid and ignore it pretty easily.

00rob00 Rob00Rob's picture

Doesn't matter to me. Never used it just learned from trial and error as well how to actually use my cameras feature and such. Took time but now I know

antoine amanieux's picture

what will happen when all cameras have an electronic variable nd (that is just a cheap lcd so i see no reason to not incorporate it )?

K P's picture

All the laws still apply...

John Hess's picture

It's still not a triangle...

K P's picture

The triangle is only a way for people to visualize the relationship of these timeless laws of physics. You could make it whatever kind of graph you like to help yourself understand.

Matthew Saville's picture

Apparently, film has ceased to exist to most digital photographers.

This article was an attempt at explaining the truth behind how light-gathering works on digital sensors versus how it used to work on film. Fair enough; ISO is indeed not related to the actual number of photons hitting the sensor. However, considering that there are still innumerable advantages to minding your ISO in the field, it ought to continue being called the exposure triangle, and the true camera geeks out there can have their exclusive little club where they wink at each other because "they know better" about the truth behind digital gain. Most photographers are much better off just understanding how noise and dynamic range are affected by changing ISO, and that's it.

John Hess's picture

Eliminating the Exposure triangle is not about "not minding your ISO"... ISO is simply NOT part of exposure. ISO is what happens AFTER Exposure

We control our EXPOSURE (scene lighting, ND filters, Aperture, Shutter Speed) for a given ISO.

This kind of sloppy equivalency is why the triangle is so egregious... It leads people to think of ISO as part of exposure... When it is by definition not.

Logan Cressler's picture

Not sure that I agree that f/2.8, 1/250 ISO 100 is the same exposure as f/2.8, 1/250, ISO 4000

K P's picture

If you don’t think ISO has anything to do with exposure. You’d better relearn what you think you know. It’s everything. Just because it’s a little flexible in post if you shoot raw doesn’t mean it’s not a pillar of exposure. Try shooting an 8bit jpeg and trying to adjust your exposure after the fact. You won’t. “International standards organization”. Is what it stands for and 100 ISO/ASA should have the same sensitivity to light on any camera or film. That’s why it’s important. It’s a known standard of sensitivity to light, so you can make these calculated relationship changes using the “triangle”

michaeljin's picture

"“International standards organization”. Is what it stands for and 100 ISO/ASA should have the same sensitivity to light on any camera or film."

No and no.
1. ISO is "The International Organization for Standardization"
2. Digital ISO is not standardized across manufacturers and may not necessarily match the sensitivity of the same ISO film because of this. Furthermore, the ISO of any given film stock is simply a manufacturer-suggested "box speed" and there's a range of speeds that you can shoot it at as long as you adjust the development time accordingly. There are several ISO 400 films (such as Tri-X) that are widely considered to not TRULY be 400-speed, but the 400-speed rating and published development times are considered to be pushing the film stock. The listed development time is likewise simply a suggested starting point. Many film shooters will rate the film speed of a given stock differently from the box speed and come up with their own development times. So it's all a bit more complicated than what you suggest.

K P's picture

The Acronym is out of order from the actual name of the organization? Good to know but the point of my statement is the same and the differentiation is frivolous.

Michael, I hear what you're saying about ISO and technically I can see how you're correct but I think maybe you're getting mired down in an irrelevant detail of how it works. Sure you can vary from the box speed of film and change the gain of a digital sensor. But you're really making a creative choice at that point. With film, you're affecting grain contrast and color and you will lose out on the maximum capability of the film as understood by the manufacturer who has given it it's ISO/ASA rating. (depending on the film. A lot of them are really flexible) You are also choosing a different ISO to interpret your creative choice, and compensating for that in development if you're using film or Raw capture. And that still falls within the parameters of the model I've described in the earlier post.

Yes,a photographer will refine this process to his or her own tastes or opinion of how things ought to look. But ISO is the law that gives you a well-defined starting point. I don't see how I'm not correct.

michaeljin's picture

It's not necessarily just a creative choice because a lot of manufacturers have posted box speeds that are not actually optimal for the film stock if you want to preserve your tonal details. This is admittedly FAR more of an issue with black and white films than it is for color. Digital ISO is also not standardized at all so ISO 400 on Fuji can differ from ISO 400 on Canon in terms of the "sensitivity" to light (or, technically, how much gain is applied).

I agree that ISO is an important part of exposure for practical purposes, but if you're going to get into technical details to support your point, the technical details ought to be correct.

K P's picture

I think my details are correct. I don't agree that "a lot of manufacturers have posted box speeds that are not actually optimal for the film stock". I find them to be reliably accurate when shot at box speed. Maybe there's something wrong with your meter/camera? The same with digital cameras. I get nothing but consistent results with my external meter. You know a meter is like a paintbrush, There are lots of different ways to use it to get different results. IF you are good with it it can serve you well, and if you're not it will be your enemy.

The iso standard allows for standardization. and even if you don't agree that the manufacturer of the product rated it correctly, it will be the same from one roll to the next due to ISO standardization. the portra400 you shot on a few years ago will be the same speed as the one you shoot with two years from now, with a negligible difference.

What am I missing Michael?

michaeljin's picture

Again, it's complicated... C-41 films are more accurate in this regard because C-41 is a standardized commercial process in which the development time is designed to be the same for every roll. You can still push and pull, but there's generally less experimentation done with it than with traditional black and white films where it's the freaking wild wild west. You would be correct to rate a C-41 film at whatever speed is required to achieve "proper exposure" using the standardized development process. There is not such standardization with black and white films. Take 15 different 400-speed stocks and you'll probably get 10 different development times for a given chemical and dilution. So given that, could you truly say that those films have a "standardized ISO"? What is it standardized to when there's no image without development time which can vary wildly with chemical or dilution?

(You also got the name of the organization wrong, which is the other thing that I pointed out.)

K P's picture

You are definitely reaching. There are different developing times for different stocks because they all have different chemical makeup and this require different times and methods of processing. That has no effect on the ISO standardization. The films/sensors have been tested extensively by the manufactures and the have found the optimum contrast, resolution, color etc.. for the given stock, thus it’s ISO rating. It is inconsequential that a film stock can be pushed or pulled or that you can still get a good image if you messed up the exposure. If you don’t use the box speed your either messing up or are making a creative choice. You say that there’s no image without processing. But theirs also no image without exposing. Proper exposure is really important to getting the image you want. So yeah I can really say that all those B&W films have a standardized ISO. It’s on the box!

Are you telling me that you just throw your film in and play roulette with the ASA dial and cross your fingers?

I did also address your correction of the proper ISO acronym in a previous post.

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