The 50-150mm f/2.8 EX DC OS HSM APO Lens for Sigma Cameras from Sigma is a fast f/2.8 telephoto zoom lens with a 50-150mm focal length (75-225mm equivalent in 35mm format) designed for cameras with a Sigma SA mount. This long autofocus telephoto gets you close to the action, and it has an optical image stabilization system that makes it possible to hand-hold the lens at up to four shutter speeds slower than usual, while maintaining sharp, shake-free images. The Hyper Sonic Motor (HSM) gives you quiet, high-speed autofocus, and also allows full-time manual focus override.
Six SLD glass elements help prevent chromatic aberrations, and provide excellent image quality throughout the zoom range. Super Multi Coating on the glass surfaces reduces flare and ghosting, and helps ensure high-contrast images. The 9-blade diaphragm gives a very pleasing quality to the out-of-focus areas of your photos (generally known as bokeh). A built-in tripod collar provides a solid mount when it's placed on a tripod.