THERE ARE THREE SETTINGS that allow you to adjust the exposure: shutter speed, aperture, and ISO. The combination of these three settings is what creates the exposure. To understand the idea behind equivalent exposures we need to quantify the amount of light that reaches the sensor and understand how that is determined by the relationship between the three exposure settings.

The unit of measurement used to describe the amount of light reaching the sensor is called a stop. When you double the size of the aperture and let in twice as much light, you are letting in an additional 1 stop of light. When you ...

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