Solving The Mystery of Exposure Triangle

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Welcome photo ninja, to this guide on solving the mystery of exposure triangle in photography. I understand, almost everyone can’t wait to snap away with their new cameras… but just cannot get things right. A lot of the photos just turn out too bright or too dark.

That was how I was as a beginner too, and I figured out that I needed to learn the basics. I looked at many tutorials online, and the exposure triangle was the first thing to pop out.

It sounds so very scary at first, but in fact, it only took me 15 minutes of dedicated reading to learn all about the exposure triangle. The rest is just like riding a bicycle. The more I go out to shoot and practice, the more I catch the gist of how to control my shots.

If you want to take better pictures, learning the most basic foundation of digital photography is a must. So what is it when the photographers say “exposure triangle”?

It turns out to be something very simple. Exposure simply means “exposing the camera’s sensor to light when you take a picture”. Easy?  🙂

As for exposure triangle, there is nothing mythical. It is simply 3 “elements” that will control how your photo looks – aperture, shutter speed and ISO. Master the control of the 3 elements, and you will photos the way you want it to be.




Section  A
What is it for?

Section B

Section C
Shutter speed

Section D

Section E

Section F
Not just right

Section G
Cheat sheet

What’s next?




I read your mind – Just what in the world are aperture, shutter speed and ISO? What do they do? Why the heck is this triangle so important? Don’t be overwhelmed, we shall go through these one step at a time.


First off, if you have not already tried shooting with the manual mode, please do so.If you already have, you will notice that sometimes photos turn out way too dark or way too bright. (Unless you have already mastered the exposure triangle)

  • When the camera does not get enough light, a dark under-exposed photo will be produced.
  • When the camera gets too much light, a bright over-exposed photo will be produced.

We normally aim to produce “just right”, and the exposure triangle will help you to achieve that – by “balancing the 3 elements” of aperture, shutter speed and ISO.



We shall now dive into the first “element” called aperture. Don’t be intimidated by the technical term, this is actually something very simple and stupid.

See those circular blades thing in your lens? Those are called aperture blades. They open and close to certain sizes, controlling the amount of light that goes into the camera.

  • Captain obvious – They more the blades open up, the more light gets into the camera; as they close, the less light gets into the camera.
  • Not-so-obvious – The blades open up to certain standardized diameters called f-stops or f-numbers. E.g. f/1.8, f/2.8, f/8, f/22

The more light the better now right? Well, not exactly. The f-stops also control something called “depth of field”. Simply put, a photo with deep depth of field has everything in focus, from from to back.

A photo with shallow depth of field will have the foreground in focus, but background blurred… or vice-versa. An example will make things clearer:

To sum up aperture :

  • The smaller the f-number, the larger the opening; Allowing more light to get in, but a shallow depth of field.
  • The bigger the f-number, the smaller the opening; Allowing less light to get in, but a deeper depth of field.

Confusing? Refer to the “cheat sheet” below, and experiment for yourself by shooting in the “aperture mode” to find out more. Try out various shots at different f-stops, and see the effects of it.



The next “element” is called shutter speed. This is much more easier to understand than aperture, I promise. Shutter speed in simple terms mean “how long to expose the photo for”.


The effects of shutter speed are straightforward as well.

  • A slow shutter speed usually end up with motion blur… or camera shake.
  • A fast shutter speed will “freeze frame”. Good for capturing those water droplets in mid-air and stuff.

Exercise – shoot in the “shutter priority” mode, and see for yourself how different shutter speeds can affect motion.



Now to last element, ISO. Which is simply the sensitivity of the camera’s sensor.

  • The lower the ISO number, the less sensitive the sensor is to light. But this also creates a clean image.
  • The higher the ISO number, the more sensitive the sensor is to light… but also creates something called “electronic noise”.
  • So summary, keep the image clean. Try keep the ISO as low as possible unless you are forced to.

I have to insert a small section of history here on ISO for educational purpose. For those who are sharp, you have probably realized that ISO refers to the International Organization for Standardization. Yes, that is exactly what it is.

In the film days, each roll of film is graded by the “ISO Film Speed”. That is, how much light is required to “burn an image” in to the film. The higher the ISO Film Speed, the more sensitive the roll of film is. That is still true today. Even when we are no longer using film, “ISO Speed” is still used in electronic sensors.



Now that you know the “3 elements”, the exposure triangle is exactly all about how to balance them. For example:

  • To take a landscape photo, you need a deep depth of field (f/11). Since less light gets into the camera, you need to compensate with a longer exposure time or boost the ISO.
  • To take a photo of a water droplet, you need a fast shutter speed. To compensate for that, you need more light into the camera at once – large aperture or boost the ISO.
  • You are shooting indoors with low light, but do not want to lose too much depth of field. To compensate for that, you boost the ISO and set a slightly longer exposure time.

How do we learn how to balance the triangle? This is exactly the part where I mentioned, it’s like riding a bicycle.

Which setting to use? It’s all about experimenting, what you want the photo to look, and it’s all about experience. There are really no rules to here.



Remember that I mentioned “we usually aim for just-right exposure”? Well, “just-right” exposures are not always right. There are times where we deliberately over-expose or under-expose photos for that creative effect. A classic example, silhouettes.

Every photographer will mention this, and so shall I – There are no “perfect exposures”. The only “perfect exposure” that you can have is when you master the exposure triangle and photographer’s mind. You are a master when you can freely produce the image that you have in your mind.



Is the whole triangle thing too confusing? I have created an exposure triangle “cheat sheet” below.

If you don’t find it ugly, please feel free to save the image below (right click -> save image as) for your future reference… or simply click / tap on it to view the full image.



It may be difficult at first, and may take many tries to get things right. But I really do not recommend newbies to jump straight into shooting in manual. Start with something simple first :

  • Shoot in the aperture mode, see for yourself the effects of a large and small aperture.
  • Shoot in the shutter mode, see for yourself the effects of a slow and faster shutter speed.
  • Whenever unsure, switch to the auto mode. Take a photo, and see why the camera uses that setting. Tweak that setting, and see the difference.

The most important thing about mastering the exposure triangle is, you need to go out and shoot. It can be frustrating at first, but once you master it, all the settings will come naturally. So go crash over this barrier and have fun!

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