released in 2005, it is the world's 1st lens to give f/2.0 over the entire zoom range
now this would make a brilliant available light portrait lens with nice bokeh ~$US2500 or $A4400
BUT weighs 1.8kg with tripod lock which is similar to Canon's 70-200mm f/2.8 IS but 1 stop faster.
a much loved lens for videographers due to its constant f/2.0 aperture throughout the zoom range