Currently there are 19 native Telephoto Zoom lenses for Sigma SD1 Merrill and all of these lenses are autofocus (AF) type.
Sigma SD1 Merrill doesn't have a sensor based image stabilization system but 12 of these Telephoto Zoom lenses features optical image stabilization.
Since Sigma SD1 Merrill has environmental sealings (Weather Sealing), you may like to couple your camera with one of these 5 Telephoto Zoom lenses with Weather Sealings.