the Sigma 150-600 millimeter 5-6.3 DG HSM OS contemporary was created around the concept of maximum portability meets utmost image quality in a variable aperture hyper-telephoto zoom lens. Light weight and compact, this S zoom can handle any long-reach photographic situation one may encounter. This 150-600 millimeter contemporary boasts updated Sigma technology such as a quiet and optimized hyper sonic motor (HSM) and a new optical stabilizer (OS) with an accelerometer for improved panning photography both vertically and horizontally, essential for birding, wildlife and motor photography. The Sigma 150-600 contemporary also touts a new zoom lock switch that can be locked at any focal length and a new manual override (MO) switch is incorporated for improved focusing control. Working with the Sigma USB dock, This lens allows for maximum customization such as firmware updates and adjustments to the focus limiter, AF speed and os view. specificationslens construction: 20 elements in 14 groups> angle of view: 16.4-4.1minimum focusing distance: 280 cm/ 110.2in.diaphragm blades: 9minimum aperture: f22filter size (mm): 95mm> maximum magnifications: 1: 5.2dimensions: 4.1 x 10.2 in.Weight: 4.3 lb.