I just returned from a three week trip to Costa Rica with the new Sigma 50-150 f2.8 lens in tow. A few thousand photographs later and I came back with a good feeling about this lens. The lens is very sharp, focuses quickly and overall is a joy to use. I have put some "real" (not brick walls) images at http://www.pbase.com/islaguy/sigma_50150 for those that are interested. Photos from my trip can be found at http://www.pbase.com/islaguy/costa_rica comments are always welcome.