Sigma | 50-150mm f/2.8 EX DC HSM Lens for Nikon Digital

Sigma | 50-150mm f/2.8 EX DC HSM Lens for Nikon Digital

This is the most affordable constant aperture lens that I could find. I am still getting used to it (the autofocus reacts a little differenlty than my other lenses), but the depth of field on this is amazing, and it's turned out some great pictures.