what does the G mean on lense
Lenses with the 'G' designation don't have an aperture ring. Aperture has to be set through the camera. AFS lenses have the focusing motor built into the lens. Usually much quieter and faster focusing than regular AF lenses that have the focusing motor in the body and mechanically focus the lens.: The lens has no aperture control ring and is designed to be used with cameras that allow setting the aperture from the camera body. G lenses also provide Distance information to the camera.