Sigma 70-200mm f2.8 APO EX DG HSM Auto Focus Telephoto Zoom Lens                  

This telephoto zoom lens has a large maximum aperture of f2.8 which remains constant throughout the zoom range and it is optimized for digital SLR cameras.

Two pieces of SLD (the special low dispersion) glass in the front lens group and another two in the rear group offer excellent correction of chromatic aberration. High optical performance is demonstrated throughout the entire zoom range.

The new multi layer lens coating and lens design reduce flare and ghost, which is a common problem with digital cameras and also creates an optimum color balance. An inner focusing system eliminates front lens rotation, making the lens particularly suitable for using the petal-type lens hood supplied and circular polarizing filters. Since focusing and zooming do not change its overall length, ease of handling and operation is assured. A rotating tripod mount can be conveniently detached if required.

The Hyper Sonic Motor (HSM) ensures a silent, high-speed AF function as well as full-time manual focusing capability.

The lens can be used with the 1.4x EX or 2.0x EX Apo Tele Converters (optional), becoming a 98-280mm F4 Autofocus telephoto zoom lens or a 140-400mm F5.6 Autofocus telephoto zoom lens respectively.
Features
Four Special Low Dispersion (SLD) glass elements produce excellent image quality throughout the entire zoom range
New coating and lens design minimize flare and ghost.
Inner focusing and inner zooming systems retain external dimensions for ease of handling.
HSM provides silent, high-speed and precise auto-focusing with full time manual focus override.

Specifications
Construction 14 Groups /17 Elements
Angle of view 34.3°-12.3°
F stop range 32
Closest Focusing Distance 180cm /70.8"
Maximum Magnification 1:7.8
Filter Size 77mm
Dimensions (Length x Diameter) 7.2" (184mm) x 3.3" (86.2mm)
Weight 44.7oz. (1270gr)
For Canon
For Nikon
For Pentax