The Exposure Triangle: Understanding the Fundamentals of Photography

January 22, 2023  •  Leave a Comment

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Photography is an art form that requires a combination of technical skills and creative vision. One of the most important concepts in photography is the exposure triangle, which refers to the three elements that determine the exposure of an image: aperture, shutter speed, and ISO. These 3 fundamental functions of a camera all control the driving force behind photography - light. Let's explore each of these elements in depth and discuss how they work together to create a well-exposed image.

 

Aperture

 

Aperture refers to the size of the opening in the lens through which light enters the camera body. The size of the aperture is expressed in f-stops, with larger f-stops indicating a smaller aperture and vice versa. Aperture affects two things in an image: depth of field and amount of light.

Close up of camera apertureCamera ApertureLens front side exposed aperture blades diagram of camera aperture at different opening stagesCamera ApertureLens front side exposed aperture blades

 

A large aperture (small f-stop such as ƒ1.2 or ƒ1.8) creates a shallow depth of field, which means that only a small, narrow portion of the image will be in focus (typically in a plane parallel to the camera sensor), while the rest will be blurred. This can be useful for creating a more dramatic and artistic look, especially in portraits and macro photography. On the other hand, a small aperture (large f-stop such as ƒ11 or ƒ16) creates a large depth of field, which means that most of the image will be in focus (again, typically on a deeper plane parallel to the camera sensor). This is useful for landscapes, architectural photography, and other situations where you want to keep everything in focus.

Shallow depth of fieldShallow depth of field Large depth of fieldLarge depth of field

In addition to depth of field, aperture also affects the amount of light that reaches the camera sensor. A larger aperture lets in more light, which can be useful in low-light conditions, while a smaller aperture lets in less light, which can be useful for controlling the exposure in bright light. You can think of this in the same way the human eye behaves - as you are in a darker environment your pupil dilates and opens to let in more light; inversely, the brighter the environment, the more your pupil will constrict to limit the amount of light.

 

Shutter Speed

 

Shutter speed refers to the amount of time that the camera's shutter is open, allowing light to reach the sensor. Shutter speed is expressed in seconds or fractions of a second, such as 1/60s, 1/125s, etc. Shutter speed affects two things in an image: motion blur and amount of light.

Camera Sensorcamera Sensor

 

A fast shutter speed (e.g., 1/1000s) will freeze motion in an image, which is useful for capturing fast-moving subjects such as athletes, birds, or vehicles. On the other hand, a slow shutter speed (e.g., 1/4s or slower) will create motion blur, which can be useful for conveying a sense of movement or for creating a more artistic look.

1.6 sec1.6 sec

1/250 sec1/250 sec

Motion blur - long shutter speedMotion blur - long shutter speed Freeze motion - short shutter speedFreeze motion - short shutter speed

In addition to motion blur, shutter speed also affects the amount of light that reaches the sensor. A slower shutter speed lets in more light, which can be useful in low-light conditions, while a faster shutter speed lets in less light, which can be useful for controlling the exposure in bright light.

 

ISO

 

ISO refers to the sensitivity of the camera's sensor to light. A higher ISO value means that the sensor is more sensitive to light, while a lower ISO value means that the sensor is less sensitive to light. ISO affects the amount of light captured in an image and the noise level in the image.

 

A high ISO value (e.g., ISO 800 or higher) can be useful in low-light conditions, as it allows you to use a faster shutter speed or smaller aperture to control the exposure. However, a high ISO value can also result in more noise in the image, which can be noticeable as graininess or speckles in the image. A low ISO value (e.g., ISO 100 or lower) is useful for controlling noise in the image, but it may require you to use a slower shutter speed or larger aperture to control the exposure, especially in low-light conditions.

High ISO comparisonHigh ISO comparison - ISO 8000

ISO 8000 - crop to show additional noise in image

 

Balancing the Exposure Triangle

 

Now that we've covered the basics of each element in the exposure triangle, let's talk about how to balance them to create a well-exposed image. The key is to understand that aperture, shutter speed, and ISO are all interrelated and affect each other.

ChildChild PuppyPuppy

For example, if you use a large aperture to create a shallow depth of field, you'll need to compensate by either using a faster shutter speed or a higher ISO to prevent overexposure. Similarly, if you use a fast shutter speed to freeze motion, you'll need to compensate by either using a smaller aperture or a higher ISO to prevent underexposure.

 

The key to balancing the exposure triangle is to understand the relationship between aperture, shutter speed, and ISO and to adjust one or more of them to achieve the desired exposure. This may take some trial and error, but with practice, you'll become more familiar with how to balance the exposure triangle to create the look and feel that you want.

Couple on bridgeCouple on bridge

 

Final thoughts

 

The exposure triangle is a fundamental concept in photography that every photographer should understand. By mastering the art of balancing aperture, shutter speed, and ISO, you'll be able to create well-exposed images that capture your creative vision. So next time you're out shooting, experiment with different combinations of aperture, shutter speed, and ISO and see what works best for you. Happy shooting!

 

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