Tamron 17-35mm f/2.8-4 DI OSD Lens for Nikon F MountProduct Description: Lightweight and versatile, the Nikon F mount 17 35mm f 2. 8 4 DI OSD Lens from Tamron covers a range of wide angle focal lengths while maintaining a bright maximum aperture. The variable aperture of f 2. 8 4 provides exceptional control over depth of field and allows enough light in to excel in many low light situations. Housed in the lens, which weighs slightly more than a pound, are 15 elements in 10 groups that include Tamron's