The AF-S on the lens tells you what kind of focus the camera has, there are two types. AF and AF-S.  What is the difference between and AF-S and AF lens? and how do i know which my lens is? Well first, look at the front of your lens or continue reading to find out if the model you have has a build in auto focus (AF) or if you have to do it manually (AF-S)

          Nikon offers two types of auto focus digital cameras bodies : those with auto focus drive monitor and those with the motor in the lens. D5100, D5000,  D3100,  D3000,  D60 and the D40 do not have a focus monitor in them but they require the lens to have a focus monitor. With an AF lens you would have to manually turn the focus ring