Sigma 17-35mm f/2.8-4 EX DG IF HSM Aspherical Super Wide Angle Zoom Lens for Nikon SLR Cameras

From the Manufacturer Sigma's 17-35mm f2.8-4 EX is one of the EX Series lenses. It combines a fast f2.8-4 maximum aperture with ultra wide angle zoom lens of 17-35mm. It incorporates aspherical lens elements in the front, as well as rear lens groups, to correct spherical aberration. It also incorporates internal focusing to prevent deterioration of the optical quality at close distances and to eliminate rotation of the front barrel during focusing. A "perfect hood" is provided. The lens materials used in this new lens are lead and arsenic free ecological glass. Aspherical lenses Lens elements that are not spherical can reduce the total number of elements required in a lens design. They can deliver better performance while reducing weight and size. Aspherical lenses maximize optical performance while minimizing lens size and weight. Aspherical lenses help reduce some of the problems usually associated with wide angles and zooms, such as lens flare and edge distortion. They also help deliver higher quality telephoto images. Specifications: Lens Constructions: 14 groups, 15 elements Angle of View (Diagonal): 103.7º-63.4º Number of blade in diaphragm: 8 Minimum Aperture: f32-45 Minimum Focusing Distance: 19.7 inches Magnifications: 11.5x Filter Size: 82 millimeters Dimensions (Dia x Length): 3.5 by 3.3 inches Weight: 14.1 ounces

• 17mm Ultra-Wide-Angle to 35mm wide-angle zoom lens for Nikon AF cameras
• 11.5x total magnification with Distance Information Function for Nikon
• Focuses as close as 19.7 inches at all focal lengths and as far as infinity
• Aspherical lenses maximize optical performance in a smaller and lighter design
• Perfect hood reduces light glare