igma's APO 800mm f5.6 EX is one of the EX Series lenses and is fully compatible with all Nikon Digital SLR cameras including the D40 and D40X. It is an Apochromatic ultra-telephoto lens with a fast F5.6 maximum aperture, and incorporates two Extraordinary Low Dispersion glass elements (Abbe number 90.3), to reduce chromatic aberration to minimum limit. It also incorporates internal focusing which enables responsive and fast auto focus speed.
The AF drive for Sigma SA, Canon and Nikon S.L.R. cameras features the ultra-quiet Hyper Sonic Motor (H.S.M.). This new lens also incorporates a rotary filter holder in the rear part of the lens barrel, which enables the use of a polarizing filter. Sigma's dedicated APO EX Tele Converter 1.4x MF and 2x MF can be used with this lens. The lens materials used in this new lens are lead and arsenic free ecological glass.
Construction 10 Groups /13 Elements Angle of view 3.1° F stop range 32 Closest Focusing Distance 700cm /275.6" Maximum Magnification 1:8.8 Filter Size 46mm (Rear) Dimensions (Length x Diameter) 156.5 x 520mm / 6.2 x 20.5" Weight 4,740g / 167.2oz