What is meant by f-stop?
This equals the focal length of the lens divided by the diameter of the aperture (as seen from the front). Practically speaking, the f-stop is the wide of the lens opening you’re using when you take a photograph. If the aperture diameter is 1/2 the focal length, the f-stop is f/8. Automatic cameras automatically adjust the f-stop for each picture. Manual cameras allow the photographer to adjust the f-stop according to the needs of each shot.