testing out a new lens, the Sigma APO 150-500mm f5-6.3 DG OS. it's not an easy to handle lens, the AF is a little narrow, so it's easy to be slightly off focused, but tracking is amazingly fast. the weight is not much different than 70-200mm f2.8, so handheld is fine, although a monopod wouldn't be a bad idea. the small aperture somewhat handicaps the D300 at ISO 400+ if lighting conditions aren't perfect, but overall, it's one of the best, if not the best, bargains you can get for less than $800US.