Sigma 170-500mm f/5-6.3 DG APO Aspherical AutoFocus Telephoto Zoom Lens for Pentax AF Cameras

This great lens combines a 5 lens group zoom system with an aspherical lens element to deliver sharp high contrast images throughout the entire zoom range. Using Sigma's unique apochromatic lens design and three SLD glass elements, the aberrations usually found in ultra-telephoto lenses have been eliminated.

The new DG multi-layer lens coating and lens design reduces flare and ghosting, and creates an optimium color balance resulting in better picture quality through the entire zoom range on both film and digital SLR's.

And with Sigma's focusing system, the front lens group doesn't rotate, which makes using polarized filters a snap. A lens hood and removable tripod collar are included as standard components.