Lens Construction:23 Elements in 18 GroupsAngle of View:20.4-8.2 degreesNumber of Diaphragm Blades:9 (Rounded diaphragm)Minimum Aperture:F22Minimum Focusing Distance:150-250cm / 59.1-98.4''Filter Size:105mmMaximum Magnifications:1:8.1 (at 200mm focal length)Dimensions (Dia x L):121.4 x 291mm/4.8'' x 11.5''・Designed for use with full frame digital SLR cameras. May also be used with smaller APS-c size sensors・Splash-proof feature protects the lens from the effects of harsh weather conditions・Offers Sigma's OS System (Optical Stabilization) allowing handheld photography even in low-light situation・HSM (Hyper-Sonic Motor) ensures a quiet & high-speed auto focus・FLD glass elements with performance equal to fluorite glass for compensate for color aberrationSigma APO 120-300mm F2.8 DG OS HSM (137-101) Conventionally large aperture lenses for 300mm F2.8 have been loved by professional users due to their brilliant capability of depiction and bright aperture value. It has established a solid standpoint in the world of photography. Based on the concept that turning a 300mm F2.8 lens into zoom lens would enable photographers to expand the scope of shooting we have developed 120-300mm F2.8 lenses and released them into the market. It is not simple to decide on a composition with a 300mm lens. Especially for sports and theatrical shows shooting positions are almost always fixed and changing lenses could lead to missed photographs. By adding a zoom function with the large aperture 300mm F2.8 lens it no longer requires other interchangeable lenses and rotation of the zoom ring will offer excellent framing. In other words when conditions are difficult this high-performance lens gives you more scope to express yourself in the shots you take. Sports line lenses deliver high action-capture performance Sigma is organizing all its interchangeable lenses into three product lines Contemporary Art and Sports. While offering sophisticated optical performance and expressiveness our Sports line lenses deliver high action-capture performance enabling photographers to get exactly the shots they want. With their high-level optical performance and expressive power these lenses can capture fast-moving subjects eve n at distance. This high-performance line also offers a variety of functions to aid the photographer in challenging conditions and scenarios. The SIGMA 120-300mm F2.8 DG OS HSM is the first product from the ''Sports'' line. Besides sports photography the lenses are also perfect for nature shots featuring birds wild animals and other wildlife and for capture of aircraft trains racing cars and more. Another major feature of our Sports line lenses is their wide range of customization functions: using the software provided all sorts of settings can be tailored to the personal preferences of the photographer. Dust-proof and splash-proof construction For professional purposes we have achieved excellent durability by incorporating dust-proof and splash-proof parts for joint parts such as mount attachment manual ring zoom-ring switches for customization and external switch panels. It prevents dust and dirt from entering the lens. Also the usage of the zoom ring and focus ring is well positioned for shooting situations. High image quality close to fixed focal length lens. This lens incorporates 2 FLD (''F'' Low Dispersion) glass elements which have performance equal to fluorite 1 SLD (Special Low Dispersion) glass element and compensate for the color aberration at the utmost. The design also compensates for sagittal coma flare and minimizes the blurring of a point light source in peripheral areas. It offers very high image quality close to fixed focal length lens. Incorporation of focus limiter Excellent usability is achieved by incorporating inner focusing and zooming that requires no change in the length of the lens for focus and zoom. It is possible to use with a rounded filter such as a Circular Polarizer as the front part of the lens is fixed. Due to the focus limiter offering adjustable range of auto focusing this lens can provide fast focus setting. The USB dock enables users to change the range of the auto focusing at the discretion of users' creativity. Ease of use Many parts of this lens have been designed for comfortable usage. For example the design of the zoom ring is concerned with a texture when you hold it the position of printed letters and the 4 control switches with integration-considered shape of the screws. Included accessories such as the removable lens hood and the newly designed tripod collar with strap ensure added ease of use. Newly developed ''USB DOCK'' exclusively for new product lines Based on these new lines we have developed special software (SIGMA Optimization Pro) that can update the lens firmware and adjust parameters such as focus. In addition the lenses from our Sports line have customizable AF speed focus limiter and OS function. The ''Custom Mode Switch'' is the device for further customization on the dedicated lenses. Flare and ghosting conscious design SIGMA's Super Multi-Layer Coating reduces flare and ghosting. It provides sharp and high contrast images throughout the entire zoom range. Excellent in handheld photography for telephoto shooting This lens incorporates the OS system which offers the use of shutter speeds approximately 4 stops slower than would otherwise be possible ensuring the excellent use in handheld photography for telephoto shooting. The OS system has two modes - OS mode 1 is suitable for general photography and OS mode 2 is best for panning shots of subjects such as planes or racing cars. It is possible to adjust the OS using the optional USB DOCK. Quiet and Fast AF The HSM (Hyper Sonic Motor) ensures high speed and quiet AF as well as full-time manual focus override by rotation of the focus ring. With the enhanced AF algorithm smoother AF is achieved. The full time manual which offers further adjustment after focusing with AF mode is possible. By using USB Dock you can change and adjust the AF speed at your convenience. Incorporating Rounded Diaphragm The 9 blade-rounded diaphragm creates an attractive blur to the out-of-focus areas of the image. APO Tele-Converter (Optional) The addition of Sigma's 1.4x EX DG APO or 2x EX DG APO TELE CONVERTER produces a 168-420mm F4 AF telephoto zoom lens or a 240-600mm F5.6 AF telephoto zoom lens respectively. Brass made bayonet mount This lens incorporates a brass made bayonet mount which has both high accuracy and durability. A special treatment to reinforce its strength is applied to the surface giving it greater strength and making it highly resistant to long-term use. Evaluation with Sigma's own MTF measuring system ''A1'' We used to measure lens performance with an MTF measuring system using conventional sensors. However we've now developed our own proprietary MTF (modulation transfer function) measuring system (A1) using 46-megapixel Foveon direct image sensors. Even previously undetectable high-frequency details are now within the scope of our quality control inspections. The SIGMA 17-70mm F2.8-4 DC MACRO OS HSM will all be checked using this ''A1'' before they are shipped. ''Made in Japan'' All Sigma's manufacturing - right down to the molds and parts - is carried out under an integrated production system entirely in Japan. We are now one of the very few manufacturers whose products are solely ''made in Japan''. We like to think our products are somehow imbued with the essence of our homeland blessed as it is with clean air and water and focused hard-working people. We pride ourselves on the authentic quality of Sigma products born of a marriage between highly attuned expertise and intelligent advanced technology. Our sophisticated products have satisfied professionals and lovers of photography all over the world because our manufacturing is based on genuine craftsmanship underpinned by the passion and pride of our experts.