I got this lens a year ago from Amazon for a little more than sevenhundred, much cheaper than today price. Somehow HSM is not implemented on Minolta or Sony mount so AF is a little bit slow on my Sony Alpha A200, not super fast like on Canon or Nikon mount. Couple with 1.4X extender, I tried to take some birds but AF is slower than w/o the extender, I got like 50% of success rate. Chromatic aberration is visible if 100% crop. So my experience with birds were not very successful, but I used this lens to take my wife portraits and it did a good job. Colors were vivid and pleasing.
I think I used this lens wrongly for bird photography, I know that Canon 400 2.8 is good for that, but hey it cost maybe 5 times this lens cost. Overall I like this lens and I will keep it for a while.
Sigma 100 300mm f