It's been awhile since I purchased my first DSLR and Lens (A Canon 30D and Tamron 17-50mm) and I've come to learn two main things. First, the 17-50mm is an insanely good lens, and one I can't think of going without. Great for landscapes, nature, and portraits (though I still shy away from people when i have the camera out . I'm working on that.) I have a feeling I'll have this lens for a good long time. and Secondly, I need more range. It's not a sudden relization, but one that has slowly built up over time. Ever try to shoot photo's of a rodeo from the middle of the bleachers with a 17-50? Great for overall shots of the location, but horribly inadequate for catching the action. Then there's all the times I've missed photographing animals while exploring the local wooded areas. Add to that all the other stuff as well, and it adds up to one new thought. And what a thought it was - causing my wallet to tremble in fear. I need a new lens. So I did my research, writing out a list of what I want and don't want. I've pulled up reviews on who knows how many different sites comparing who knows how many lenses. The Canon 100-400L looked nice, but it seemed more than I was looking for. The Tamron 200-500 had a nice range, but was lacking in many respects. The Sigma 50-500 has had many, many reviews - both good, and not so good, and I almost broke down and bought it more than once . Then Sigma released a new lens, the 150-500 OS. The lens seems to me to be a mix of the Bigma and the Canon, giving up some of the lower end and adding an IS equivalent. And it's cheaper than the white glass, which is always a bonus. On the downside, none of the local stores carry it, but I did get a chance to *ahem* play with the 50-500,170-500, and 100-400L. I was talking over my dilema with my boss the other day, and he gave me his usual sage advice, "You don't drink, don't gamble, and don't smoke - Hell, go for it! A man's gotta have a vice!" So in the end I just spent more on a piece of glass that I have ever done before. I just ordered the Sigma 150-500 OS from vistek with overnight shipping. If all goes well, it should arrive this friday. I am so excited, yet there is this inkling of dread due to the 'what if it's not what I expected...'. Ah well, at least my lighter wallet will help me carry this beast around. Hopefully I can post some photo's for your review when it comes.