A couple of features make this lens stand out from its competitors. The first is the inclusion of the powered zoom drive, which is operated through a lever on the side of the lens barrel. The system is similar to the zooms on most video camcorders.

You want a fast telephoto zoom lens for everyday and travel photography; You require fast; precisely controllable zooming; You want high resolution at all focal lengths; along with good flatness of field; You'd like a lens that requires no readjustment when you fit polarisers and graduated filters.