The Exposure Triangle: aperture, shutter speed and ISO explained

The Exposure Triangle sounds like the name of a complex spy novel, but in reality this is the term used for the three fundamental elements of exposure: aperture, shutter speed and ISO. Our latest photography cheat sheet illustrates the Exposure Triangle and how it affects your camera settings.

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The Exposure Triangle Explained understanding the relationship between aperture shutter speed and ISO free cheat sheet

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The Exposure Triangle Explained

Creating a harmonious exposure using the aperture, shutter speed and ISO is a juggling act. As soon as you make a decision about one element, you'll need to compromise with another.

The trick to balancing The Exposure Triangle is to get all three elements working together so you get the results you want ,and not what the camera tells you you can have.

Because of that, it's really worth putting in the groundwork and getting to grips with the basics of shutter speed (how long the camera's sensor is exposed to the light), what an aperture is (how much light the lens lets in, which also affects depth of field) and ISO (the sensitivity level of the sensor). Once you know how to do this, there's nothing you can't do.

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Annoying problems at common aperture settings (and how to solve them)
What is ISO: camera sensitivity settings and the best ways to use them

In addition to their role in exposure, the choice of aperture, shutter speed and ISO have a significant impact on the look and feel of your pictures.

Aperture, as we mentioned above, affects the depth of field, or how much of an image appears sharp. Shutter speed also affects image sharpness, with slower shutter speeds leading to blurred images - whether that's caused by the subject moving or the camera not being held still.

The choice of ISO enables you to use the optimum combination of aperture and shutter speed when the amount of light would normally prevent you from doing so. However, increasing the ISO also reduces the quality of your images.

Use the exposure triangle (see our infographic above) to decide how to adjust the exposure: the key is that when you increase the exposure for one element (a yellow arrow), you need to reduce it for one or both of the other elements (the grey arrows) in order to maintain the same exposure.

The camera can do this for you in Program, Aperture Priority or Shutter Priority, but it's something you'll need to consider when shooting in Manual mode.

Get the hang of this relationship, and you'll gain much more control over the look and feel of every image you capture.

SEE MORE: 6 things you didn't know about using apertures, but probably should

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Understanding exposure cheat sheet

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It's also worth remembering that at one time, shutter speed and aperture were the only exposure variables you could change from one shot to the next as the ISO was set by the type of film you were using, but the introduction of digital cameras has made it possible to change ISO on the fly rather than unloading film or switching bodies.

Photographers now have more control over exposure than ever before. Now, let's take a look at some of the common questions new photographers have about exposure...

SEE MORE: 3 camera lessons every new photographer should learn (free cheat sheet)

Understanding exposure in photography

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Understanding exposure in photography everything you need to know about aperture shutter speed and ISO

Image by Marcus Hawkins. Click on the image to see the larger version.[/caption]

What's the first thing I need to know about exposure in photography?