Can We Just Kill the Exposure Triangle Already?

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?

Log in or register to post 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

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.

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.

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...

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...

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.

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.

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:

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

More comments