I haven't shot the Sigma's but I would say that based on reviews if I had to choose between the Tamron and the Sigma Contemporary 150-600 I would go with the Tamron. The Sigma Sport 150-600 is in a different price class altogether but I hear it is excellent.
harryh813 wrote:
That's awesome to know. I went to a camera store in Bradenton the other day and put that lens on my Canon 40D and they let me take it outside and take a few shots with it and mess with it a little. I'm torn between the Tamron 150-600 and the Sigma 150-600. The Sigma has one additional element and a dock for firmware updates but it's heavier and doesn't get as good of reviews as the Tamron.