What does the f-number represent?

The f-number, also known as the f-stop, represents the ratio of the focal length of the lens to the diameter of the aperture. This mathematical relationship indicates how much light is allowed to enter the camera through the lens. A lower f-number corresponds to a wider aperture that lets in more light, which is particularly beneficial in low-light conditions. Conversely, a higher f-number indicates a smaller aperture that reduces the amount of light entering the camera, resulting in a greater depth of field. Understanding the f-number is crucial for photographers, as it affects exposure and the artistic effect of the image.