Nikon users no longer have to use adapters with Zeiss lenses: superb Zeiss Planar lenses are now made in ZF (Nikon AI-S) mount versions. These are manual focus lenses, although D300 and up will sense the lenses aperture in A mode and adjust exposure accordingly. Why go through the trouble of manually focusing? Well first of all at 25mm length its not much trouble. But more importantly, you get the exceptional Zeiss sharpness, color, and high microcontrast that makes these lenses arguably the best prime lenses in the world.