Solving The Mystery of Exposure Triangle: From Auto to Manual



Welcome beginner photo ninja, to this guide on solving the mystery of what is exposure triangle in photography. I understand, most people can’t wait to snap away with their new cameras – But just can’t get things right with photos that are too bright or too dark.

That was how I was as a beginner too, and I figured that the basics are necessary for epic photos. I then looked at many tutorials online, and the exposure triangle was the first thing to pop out. It sounds difficult at first, but in fact, it only took me 15 minutes of reading to learn all about it.

As it turns out, exposure simply means “exposing the camera’s sensor to light when you take a picture”. Easy?  🙂 For the triangle part, it is referring 3 “elements” that controls how your photo looks – aperture, shutter speed, and ISO. Master the control of these 3 elements, and you will get photos the way you want it to be.




Section  A
What is it for?

Section B

Section C
Shutter speed

Section D
ISO Film Speed

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 your camera, 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 a REALLY good camera)

  • 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 simple. 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.

The obvious – When the blades open up, more light gets into the camera. As they close, less light gets into the camera. Now, some might think “the more light the camera gets, the better”. Well, not exactly. The aperture is also used to control something called “depth of field”.

  • As the aperture closes up: Less light into the camera, photo with a deep depth of field – Meaning everything is in focus, from front to back.
  • As the aperture opens up: More light into the camera, photo with a shallow depth of field – The foreground in focus but background blurred, or vice-versa.

An example will make things clearer:

Finally, you need to know that the aperture 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.

  • Smaller f-number, wider open the “gates” are.
  • Bigger f-number, the narrower the “gates” are.

Still confused? You can always refer to the “cheat sheet” at the end of this guide, and experiment for yourself by shooting in the “aperture mode” of your camera. Try to shoot at different f-stops, and see the effects for yourself.



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


The effects of using different shutter speeds are straightforward :

  • A slow shutter speed usually ends 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.

Yep. That’s it for shutter speed. The best way to understand shutter speed, is to try it for yourself by shooting with the “shutter priority” mode on your camera.



Onto the last element, ISO Film Speed. Some smart people are probably confused now. What has International Organization for Standardization got to do with this, and how is film speed related to digital photography? Well, there’s a bit of history to it.

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” into the film.  Even though we are no longer using film in digital photography, “ISO Film Speed” still applies to adjust the sensitivity of the electronic sensors in the camera.


Thankfully, ISO Film Speed (or just ISO), is another straightforward number.

  • The lower the ISO number, the less sensitive the sensor is to light.
  • The higher the ISO number, the more sensitive the sensor is to light.

Now again, some smart people may be thinking “the more sensitive the better”, since we need less light to take a photo – Wrong. The bad thing with electronic sensors is that the higher the ISO number, the more electronic noise it picks up.

So summary, keep the ISO as low as possible. Push it up only when you are forced to.



Now that you know all the “3 elements”, the exposure triangle is exactly about balancing the 3 of 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.

So how do we learn to balance the triangle? What setting should I use? This is the part where I say “it’s like riding a bicycle”. It’s all about experimenting, and what you want the photo to look like. It’s all about experience. There are no rules here, except test and practice.



Remember earlier that I mentioned, “we usually aim for just-right exposure”? Yes, I used the word “usually”. Which means, “just-right” exposures are not always the only way to go. There are times when we deliberately over-expose or under-exposed photos for that creative effect. A classic example will be silhouettes.

Every photographer will mention this, and so shall I – There are no perfect exposures. The only perfect exposure happens when you master the exposure triangle and freely produce the images 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.

Infographic – The Exposure Triangle



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!


Previous: Metering Next: White Balance


Leave a Comment