quiet, fast focusing mid-range zoom

[vanessa]

What's the equivalent of Canon's USM for Nikons? And is there any third party lens available with a silent AF motor? Nikon's 24-70/28-70 is a bit expensive, eh!

[Mhudson]

USM is equivalent to Nikon AF-S, and Sigma HSM. What's available will depend on what body you're going to be shooting.

Thanks to being a new design, the current exchange rates, and generally being the top of the line, the Nikon 24-70 is pretty expensive. Of course it is the best midrange zoom on the planet right now. The 28-70 can be had used for much much less, but if you're going to be shooting on the DX format mainly there are some other solutions.