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What is the Exposure Triangle?

When you bought your DSLR, did you expect instantly fabulous photos?

Are you finding instead that some are good, but most still suffer from the same problems you had with your old compact camera?

Don’t despair, because it’s not you, it’s the camera (I know, phew!)… and you just need to show it who’s boss!

Luckily, I can show you how…

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Better Than Snapshots

What you might not know is regardless of how expensive or fancy your camera is, when used in auto, it’s not going to take any better shots than a decent compact camera.

When the light is good, without too many variations between light and shadow, your camera will do an ok job.

The rest of the time will be a hit and miss affair.


Jumping out of Auto

When shooting in manual mode, you can take control of the settings that create your photos, and not only take photos that are technically sound and well exposed, BUT help you gain the skills to reproduce your creative vision (for example that beautifully blurry background that professional photos have).

Related: Why Shoot in Manual Mode



A ‘well exposed’ image, is when an image is neither too bright, or too dark!

It has captured just enough light to ensure you’re photo looks just the way you envisaged!

And how do we capture a well exposed shot in manual?  We wee need to balance our settings… and the exposure triangle is the concept to help you do that!


The Exposure Triangle = Balance!

When we shoot in manual, we’re choosing the settings of each of our three elements, to create a balance that results in our desired exposure. Each does something slightly different to let light into our camera.

The elements are Shutter Speed, Aperture and ISO, and collectively are known as The Exposure Triangle.

Other than bringing light to the sensor, it is just as important to understand the additional effect each element has on the shot, so that we know how to achieve our vision, how to avoid problems such as out of focus shots, and where to begin when deciding on our settings.

If our settings are out of balance then we may let in too much light…

Or we don’t let enough light in, or we end up with dark and/or blurry photos… or our subjects are out of focus!  All of these are controlled by getting just the right balance between our settings for each shot that we take!

The idea of the Exposure Triangle offers a visual way to remember that an exposure that looks great will require that we balance all of these out!


All settings BALANCED = Correct Exposure

understanding the photography exposure triangle

So What Are Our Settings?

Shutter Speed

What is it? Shutter speed is the length of time the shutter remains open after you press the shutter release. The longer it remains open, the more light gets to the sensor.

How is it measured? Shutter speed is measured in fractions of a second. Eg. 1/100 = one hundredth of one second; 1/10 = one tenth of one second. A shutter speed of 1/100 is faster than a shutter speed of 1/10.

How does it affect the photo? Shutter speed captures or freezes motion. The longer the shutter is open, the more motion it captures (resulting in blur). A faster shutter speed will freeze motion.

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What is it? Aperture is the size of the opening of the lens when you press the shutter release. The bigger it opens, the more light it lets in. The smaller the opening, the less light.

How is it measured? Aperture is measured in f-stops, a value that comes from a complicated mathematical equation based on the diameter of the lens opening. But we don’t need to go that far into it.

Depending on the lens, f stops can range from f/1.2 to f/22. f/1.2 has a very large opening, and lets in lots of light. f/22 has a very small opening and lets in less light. A low numbered aperture (eg f/2.8) is referred to as a wide or large aperture. A high numbered aperture (eg f/16) is referred to as a small aperture.

How does it affect the photo? Aperture controls the depth of field, which is how much is in focus in front of and behind your focus point. A wide aperture, say f/2.8, will have much less area in focus than a small aperture of say f/16.

What’s more, the dof is also affected by the lens length, and the distance of subject to lens.

Confused? This should help:

Low number = big opening = more light = less depth of field (blurry background)

High number = small opening = less light = more depth of field (all sharp from front to back)

To put that into a real world situation, you would use wide apertures if you wanted a sliver of focus on your subject and a nicely blurred background, such as a portrait.

You would use a small aperture if you wanted most of the scene in focus, such as a landscape photo.



What is it? ISO is a measure of the sensor’s sensitivity to light. The higher the ISO value we set on our camera when we take a shot, the more the sensor can make of the light.

How is it measured? Most cameras start at ISO 100, increasing from there incrementally by one third:

100         125         160         200         250         320         400         500         640         800         and so on

Each increment increases the sensitivity of the sensor to the light by one third more than the previous setting. This means that your sensor will be twice as sensitive to the light at ISO 200 as it is at ISO 100.

How does it affect the photo? As you push your ISO higher and higher, more and more grain becomes evident in the shot, and at very high ISO settings you might also begin to notice a loss of sharpness.  BUT pushing your ISO lets you capture images in lower light situations!


So Now What?

So this is where you need to choose a setting for each of the three elements that balance together and create an exposure. How do you do that?


The EV Meter

Before we talk about how to choose your settings, I need to mention the EV Meter. (Read more about Metering here)

The EV Meter is an indicator of how much light is hitting the camera’s sensor (see image).

Very generally speaking, when you hold your camera up to a scene, if the needle is sitting in the centre (at 0) it’s telling you it will be perfectly exposed. If it’s sitting to the right of 0, it’s telling you it’s going to be overexposed (too bright), and if it’s sitting to the left of the 0, it’s telling you it’s going to be underexposed (too dark).

The camera can be tricked by the varying tones in the scene, or the camera’s idea of perfect exposure might not match your vision, but this is a good starting point, and your settings might just require a little tweak.


Where to Start?

Start by deciding what effect you’re after – your priority is either going to be freezing or capturing motion, or a specific depth of field.

For example, if you are taking photos of your child riding a bike towards you, to freeze that motion and ensure you get no blur, your first choice should be shutter speed as that is the element which freezes or captures motion. Then you’ll use the other two elements of exposure (ISO and aperture) to get a balanced exposure.

In this instance, with your ISO set to 1-200, choose a shutter speed of around 1/800 which should be fast enough to freeze the motion of a child riding a bike.  Then choose your aperture, guided by how much depth of field you want in your photo. I suggest trying f/3.5 or the widest aperture (smallest number) your lens allows. Take a test shot of your subject. If it’s too dark, increase your ISO. If it’s too light, increase your shutter speed.

Always try to keep your ISO as low as possible without sacrificing sharp images and the overall effect. Why? Because high ISO causes grain and at the extreme end can even cause a loss of sharpness and clarity. How high? Well that depends on your camera… different models handle high ISO to varying degrees and you’ll need to experiment to figure out your own line in the sand!

That said… don’t be afraid to push your ISO, and never underexpose using high ISO, thinking it will be better to fix it later in processing than boost your ISO. It’s not!

Related: Better Results at High ISO

Conversely, if you want to photograph a portrait with a really blurry background, then aperture is going to be your first choice as this is the setting that gives you those gorgeous blurry backgrounds we all love. Once again with your ISO set to around 1-400, and presuming you have one subject that is facing the camera almost directly, start with f/2.8 which will get both eyes in acceptable focus, and will get you a beautifully blurred background. Set your shutter speed to no slower than 1/200, and take a test shot. If it’s too dark, increase your ISO. If it’s too light, increase your shutter speed.

If you want to use your fancy DSLR in manual mode, let us break it down for you with step-by-step lessons, hands on challenges and feedback on your images… pop your name on the waitlist for our next Enthusiast Photography Course.

If you’re already confident in manual mode, check out our Advanced Photography Course and let us help you elevate your photography skills to the next level!

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2 Responses to What is the Exposure Triangle?

  1. Annie December 1, 2014 at 4:19 am #

    I am very interested in the course. How much is the course?

    • LouiseGlendon December 1, 2014 at 6:54 am #

      Hi Annie,

      Thanks for your message! We’d love to have you join us on our next round! The course is kicking off at $197 but we have an early bird special that you can take advantage of if you join our mailing list! Xx
      You can find all the details here:

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