Hi, I'm a newbie here and this is my first posting. Got a dumb question here relating to the f numbers in lenses and the f numbers you set in your camera for the desired aperture size. What is their relationship? The selection for aperture size is from the camear dial, from very large aperture to very small aperture. But what has the lens f numbers got to do with the aperture size you are selecting in your camera? Why some lenses are f2.8 and others range from f3.5 - 5.6? How does it affect my aperture selection? By the way, I just bought a Nikon D40X, and using the kit lens.