Definition & Meaning of "f-number"

What is the "f-number"?

The f-number, also known as f-stop, is a measurement that indicates the size of the aperture opening in a camera lens. It is expressed as a ratio, such as f/2.8 or f/16. A smaller f-number represents a larger aperture opening, allowing more light to enter the camera, while a larger f-number represents a smaller aperture, letting in less light. The f-number also affects the depth of field in an image, with smaller numbers creating a shallower depth of field and larger numbers providing a deeper focus range.