Sigma APO 800mm f5.6 EX DG HSM Lens

The Sigma 800mm f5.6 EX HSM APO ultratelephoto lens incorporates two extraordinary low dispersion (ELD) glass elements, which help reduce chromatic aberration to the minimum limit. With a fast f5.6 aperture, this apochromatic lens also incorporates an internal focusing system to give you fast, responsive autofocus speed.
The ultraquiet hypersonic motor (HSM) lets you shoot pictures without disturbing your subjects. Polarizing filters are extremely easy to use with this lens because of its rotary filter holder, located in the rear part of the lens barrel. The optic materials are lead-free and arsenic-free ecological glass. This model is dedicated to Nikon AF SLR cameras. 
New multi-layer lens coating and lens design reduce flare and ghosting. Extraordinary Low Dispersion (ELD) glass elements produce excellent image quality and ensure sharp, quality images for film and digital SLR cameras. It enables to see the far subjects in more detail than is possible with the naked eye.