What is the Exposure Triangle?

The exposure triangle in photography refers to the relationship between three crucial settings that determine the exposure of a photograph: aperture, shutter speed, and ISO.

1. Aperture: This is the size of the opening in the lens through which light enters. It is measured in f-stops (e.g., f/2.8, f/4, f/8, etc.). A larger aperture (smaller f-stop number) allows more light to pass through, and also creates a shallower depth of field (blurred background). Conversely, a smaller aperture (larger f-stop number) lets in less light but provides a greater depth of field (more of the scene in focus).

2. Shutter Speed: This is the amount of time the camera’s shutter is open to expose light onto the camera sensor. It is measured in seconds or fractions of a second (e.g., 1/500s, 1/60s, 5s, etc.). A faster shutter speed allows less light to hit the sensor but freezes motion, while a slower shutter speed allows more light in but can capture motion blur.

3. ISO: This controls the camera sensor’s sensitivity to light. A lower ISO value (e.g., 100, 200) means less sensitivity and is preferable in bright conditions to avoid overexposure. A higher ISO (e.g., 1600, 3200) increases sensitivity and is used in low-light conditions, but it can also introduce more digital noise (graininess) in the image.

These three elements work together to determine the exposure of a photograph. Adjusting one of them requires compensating adjustments in one or both of the others to maintain the desired exposure level. Understanding and balancing these three aspects are key to achieving the right exposure for a given photograph, along with achieving artistic effects like motion blur or depth-of-field focus.