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Why the Exposure Triangle is Completely Useless

Understanding Exposure: Why the Exposure Triangle method is complete BS

The "exposure triangle" is a common tool for teaching beginners about exposure. But here's the truth about the exposure triangle: it's a terrible learning tool that is more likely to harm than help beginner photographers. I believe this tool is adopted by teachers who actually aren't that good at teaching a simple concept. They can't communicate shutter speed, aperture, ISO, and exposure in an effective way, so they teach via this "learning trick."

The Problem with The Exposure Triangle

Take it from someone who teaches photography for a living: the exposure triangle makes the simple concept of exposure seem much more complicated than it is. I know exposure, shutter speed, aperture, and ISO better than I know myself and I can barely make sense of the exposure triangle. I'm serious. It's comical how unnecessarily complicated it is. It's like watching one of those Rube Goldberg machines that turns the simple task of toasting bread into a thousand-step process.

But aside from the fact that it's overly complicated, the inherent problem with the exposure triangle is that it relies on memorization rather than understanding. You are expected to visualize a diagram with shutter speed, aperture, and ISO labeled at each respective corner, trying to remember which corner means more light, which one means less light, which side deals with motion blur, which side deals with depth of field... Unless you have a photographic memory, you're going to have to carry along an exposure triangle cheat sheet for reference.

So then what's wrong with carrying around a cheat sheet? Well, taking pictures with the help of a cheat sheet is like trying to ask a girl out on a date using a pre-written script - it'll work until she says something you weren't prepared for. The "cheat sheet" method of shooting is too slow and too inflexible. You have to be able to think fast, think on your feet, and adapt to situations quickly. An exposure triangle cheat sheet can't do that.

The Better Way to Think About Exposure

The way I teach my students about exposure doesn't rely on memory tricks like the exposure triangle because learning by memorization doesn't work. Memories can't be trusted. But if you understand how something works, then you'll almost never forget it and the whole process becomes easy. So let's talk about how to understand exposure so that we no longer need to rely on memory.

For now, let's ignore all the numbers connected to shutter speed, aperture, and ISO. The numbers are secondary, first you must understand the mechanics of exposure. If you think about the mechanics of how an exposure is made, then you'll be able to problem solve any exposure situation - no need for an exposure triangle cheat sheet. The numbers will follow.

How Exposure Works

Creating an exposure is simply the process of recording light on a photosensitive material. Traditionally that light was recorded on film, now digital cameras record light with a photo-sensitive computer chip called the "image sensor." Getting a "correct exposure" means that you recorded the correct amount of light - not too much, not too little. If you didn't record enough light, the picture would be "underexposed" or "too dark." If you recorded too much light, the picture would be "overexposed" or "too bright."

Light is made up of particles just like anything else. It's almost like water, except we can't touch it or feel it. Getting the right amount of light to your sensor is a little like getting the right amount of water to a sponge. So let's forget light for a minute. Let's talk about water.

Let's say I have a big sponge that I want to saturate with exactly 20 ounces of water from a garden hose. I can't have too much or too little - it needs to have just the right amount of water in it. And let's say I have to turn on my garden hose for exactly 1 second to get my 20 ounces. Simple enough: Garden hose turned on for 1 second and I get my 20 ounces.

Well what's going to happen if I switch out my garden hose for a fire hose? Will I have to leave my faucet on for longer or shorter now that I have a bigger hose?

Shorter. Duh. It's a bigger hose, so more water comes out, so I won't need to turn it on so long. Now how did you figure this out? Did you refer to your "water, hose, faucet triangle" on your "water triangle cheat sheet"? No, you just thought about it. This is how you should think with light and exposure. Don't rely on an exposure triangle, just think about the flow of light to your image sensor. The sensor in the back of your camera - the thing that creates the image - works just like a sponge, but instead of soaking up water, it soaks up light.

How exposure works: DSLR Camera mirror

Above is an image looking into the camera with the lens off. This is the camera "at rest" meaning it's not taking a picture right now. You'll notice there's a mirror there. That allows you to see what the lens sees before taking the picture. 

Below is an image looking into the camera while it's taking a picture. The green box in the back is the image sensor. That's what collects light (like a sponge) and turns it into an image. The mirror has to move up out of the way so the sensor can soak up the light. When the photo is done, the mirror will go back down. 

How exposure works: the digital image sensor

The aperture inside the lens is simply an adjustable opening in the lens that allows you to let more or less light through. This would be like the size of the hose. Which one of the following aperture openings would let in more light? Of course, the larger opening will.

Above is a wide aperture (low f-number), below is a small aperture (high f-number).
Guess which one will let more light through...

The shutter is the mechanism that "opens up the flow" of light to the sensor. It's like turning on the faucet. Which of the following shutter speeds (that's the duration of time the shutter is open) will let more light through: 1/100 of a second or 1/2 of a second? Well, 1/100 of a second is a much shorter time period than 1/2 of a second, so 1/2 of a second will let more light through.

How exposure works: the shutter

Here is a view of the shutter with the mirror held up out of the way. You'll notice the shutter is a set of overlapping blades that blocks the sensor from light. It keeps in the sensor in complete darkness until you actually take a photo. When you do, the shutter snaps up out of the way like a window shade so that light can soak into the sensor. When the picture is done, the shutter goes back down to block off the light. 

When you make an exposure, the shutter opens up, light flows through the aperture opening, soaks into the image sensor like water soaking into a sponge, then the shutter closes off the flow of light once enough light has been recorded.

Shutter opens > light flows through aperture > image sensor soaks up light > shutter closes. Faucet opens > water flows through hose > sponge soaks up water > faucet closes. It really is that simple. Here's a diagram demonstrating the concept:

Understanding Exposure: How exposure works on a DSLR camera

In the diagram above, you can see the aperture, shutter, and sensor all indicated along with how their setting is measured (the aperture is measured by the f-stop, the shutter is measured by the shutter speed, and the sensor is measured by the ISO). 

In the diagram below, the labels are gone to remove the clutter. This is how your camera looks when it's not taking a picture - when it's "at rest":

Understanding Exposure: How exposure works on a DSLR camera

When you take a picture, all these mechanisms have to work together to get light to the sensor so it can soak up the light and create an image. It goes like this: The mirror moves up out of the way, the aperture closes down to whatever you set it to, the shutter opens up, and the sensor soaks up the light to create an image, like this...

Understanding Exposure: How exposure works on a DSLR camera

...above is a diagram of the camera as it looks while it's taking a picture.

Some time later - maybe 1 second later, maybe 1/8000 of a second later depending on the chosen shutter speed - the camera can cease collecting light. The shutter closes to shut off the light, the aperture opens back up, and the mirror goes back down. Like this:

...now it's back to it's "resting position" ready to take another photo.

So again, shutter opens > light flows through aperture > image sensor soaks up light > shutter closes. No need to make it more complicated than that.

 

Changing One Setting Affects the Other

Much of what the exposure triangle is trying to illustrate is that if you adjust one setting (shutter, aperture, or ISO), then another setting will have to change, too, assuming you want to keep the exposure the same (i.e. collect the same amount of light). But again, you don't need an exposure triangle to understand this. It's as simple as trying to get water into a sponge. If I use a wider hose to feed water into that sponge, I won't have to leave the hose on so long. If I use a narrower hose, I'll need to leave the flow on longer. Simple.

It's no trickier than this with exposure in photography. If I open up my aperture wider, then I won't need to leave the shutter open so long (the shutter speed will be faster). If I close the aperture down to a smaller opening, I'll need to leave the shutter open longer to make up for the loss of light. More on the aperture, less on the shutter. Less on the shutter, more on the aperture. You get the idea.

But what about the ISO? Well, let's say I had some way of making my sponge (the image sensor) much better at soaking up light. In other words, I was able to increase its absorbency. Well, if I have a more absorbent sponge in my water analogy, I wouldn't need to leave the faucet on so long since it's better at soaking up water. Same goes for light. If I can make my image sensor more absorbent to light, it won't need so much time to soak it up. This is what raising the ISO does. When you increase the ISO number, you're making the image sensor more absorbent to light. As a result, the shutter will only need to "turn the flow on" for a brief time. This is why raising the ISO results in faster shutter speeds.

The Bottom Line

The exposure triangle doesn't work. It's a terrible learning tool. There is no shortcut to learning the shutter speed, aperture, and ISO. Exposure is a concept that must be understood, not memorized. Cheat sheets and the exposure triangle won't get you there. Of course you won't be an expert from this short 1,000-word explanation either. My goal here is only to show you that there is a way to understand these things through logic, analogies, and simple physics without the need for a confusing exposure triangle that relies on memorization. There is much more to it that my short summary here. This is just a foundation. That's why more than half my Introduction to DSLR Photography online course is devoted to these things alone.

Sorry to throw a sales pitch at ya, but if you want to learn these things fully, check out my Introduction to DSLR Photography online course here (perfect for beginner photographers) and in my How to Shoot in Full Manual online course here (for intermediate to advanced shooters). With a clear, concise explanation aided by example images, diagrams, and videos, you can learn exposure better than any exposure triangle can deliver.

Please download the free lesson guide and video with the full explanation of shutter speed here. Download the free lesson guide and video fully explaining the aperture here.

Links:

Featured Testimonial: Photography Basics Online Course

A student of my Introduction to DSLR Photography Online Course recently had this to say about the course:

This course is very interactive. I love the way you are always speaking with the student as if he were in front of you and I love the fact that you are always "asking yourself" questions about the logic of what it is being explained... Most of the time I was myself wondering about some aspects of the course and you were already expressing that doubt yourself. I guess this comes from a lot of teaching experience and the habit of listening always about the most charateristic learning difficulties of your students...

I like also the fact that you don't mind repeating yourself again and again on the most important concepts. I truly believe that repetition is one of the great tools for teaching. Patience is also a great aspect of the learning experience with your method. I like the way you always stop us from rushing ahead... There is a sequence to follow in your explanations and you ask us to wait until the time comes to go into further details once we are ready. I would say that these classes offer the three main qualities of a teaching experience: "Sequence, frequency and patience" Thanks!

- Philippe B.

The "Introduction to DSLR Photography" online course is my 6-week course all about the photography basics. It forms the vital foundation of photography basics that all photographers must know in order to get control of their images. From shutter speed to aperture to white balance and everything in between, this course is designed to teach my students the most important topics in the most efficient manner possible. This course is labeled as "6 weeks" but with my approach of "work at your own pace," you're free to take as long as you want to finish. You'll have access to all online photography course materials from day 1, so you can progress through the course as fast or slow as you wish. And with lifetime course access, you'll never have to worry about losing access to these helpful lesson guides and videos.

Learn more about how my online photography courses work here and read more testimonials here.

The Best Way to Learn the Photography Basics

The Best Way to Learn Photography BasicsLearning the photography basics can seem like a daunting task for beginners. Shutter speeds, apertures, ISO settings, white balance, and all the rest of that photography jargon can really make your head spin. These photography basics are important for any photographer to learn regardless of their style or niche. When taught correctly, these topics are very learnable by even the greenest students.

There are endless free resources online to learn this material, but unfortunately, there is no way to verify their validity. As a novice it's essentially impossible to determine if the information taught in, say, a YouTube video or a free blog post is actually correct. As a professional photography teacher, I can tell you honestly that it's astonishing how prevalent false information is online and how many "teachers" are unknowingly spreading blatantly incorrect material. Just because the guy in the YouTube video sounds like he knows what he's talking about doesn't mean he actually does.

The Pitfalls of Unstructured Study

Take it from someone who has worked with over a thousand photography students of all skill levels: Attempting to learn the photography basics through piece-meal videos and articles is slow, inefficient, and counter-productive. Often times the result is an over-emphasis placed on insignificant topics (like ISO noise) and a complete disregard of the most important stuff. The student will also inevitably run into a lot of conflicting information, and with no stable resource to reconcile it, the student will just be left confused and frustrated. This method of learning photography results in unnecessary confusion and a much higher probability of failure. My toughest students are the ones who do the most independent online study through unverified resources. They tend to place too much emphasis on trivial topics that the internet has blown way out of proportion like megapixel counts, lens choice, full-frame vs digital crop cameras, and high ISO noise. While, at the same time, the really important topics of exposure, manual metering, shutter speed, aperture, ISO, white balance, and exposure compensation are taught inefficiently and riddled with errors.

But here's the biggest problem with independent, unstructured learning: things are learned out of order. There is no lesson plan or curriculum on YouTube. You learn this thing over here, then that thing over there... it's all out of order. Learning these important photography basics out of order can be worse than not learning them at all. If you're studying advanced topics before the basics are well-understood, you are far more likely to give up because it seems too daunting and too confusing. It's really not too confusing, it's just that you're trying to learn it out of order. The photography basics are learned best through a structured lesson plan that keeps things in the proper order for maximum efficiency and understanding.

Learn Photography Basics From a Reputable Source

Look, I know that it's impossible for this to not sound like one big sales pitch. After all, I am trying to convince you to let me teach you the photography basics. But let's not even talk about my courses for a second. I'm begging you to learn this information from someone reputable - even if it's not me! Learn photography at a local community college or from a reputable online course provider or from a book by Ansel Adams. Learn photography from someone with experience and credentials. Learn it from a professional teacher. Someone who teaches for a living has a vested interest in teaching things well and correctly - that's how we get more clients. The guy who posted a YouTube video for free doesn't really care if the information is taught poorly or incorrectly - he's got a day job and he's doing this for free.

Professional teachers like me charge a fee to teach photography because it takes a lot of work and experience to teach these things well. I've invested over 5 years of my life to teaching photography full-time. I know how to teach it poorly and I know how to teach it well. So even if it's not with me, learn the photography basics the right way. And if you do like my teaching style, please check out my Introduction to DSLR Photography online course covering all the photography basics here or any of my other online photography courses here. Download a free preview of any of my courses using those links. Let me prove to you that I can explain this photography stuff better than you've ever heard before. And be sure to check out the testimonials from previous students here.