Sony SAL-300F28G G Series 300mm f/2.8 Super Telephoto Lens for Sony Alpha Digital SLR Camera G Series 300mm f2.8 G super telephoto lens for long-shot precision and crisp portraits, even in low light SSM (Super Sonic Wave Motor) for fast autofocus; fast internal focusing--lens length does not change 2 DMF (Direct Manual Focus) modes Electronic slider focus range selector switch; versatile focus hold with 4 buttons on lens