<p>I don't know about the Sigma 150-600, but I purchased a Tamron 150-600 last fall and I love it.<br>
I have friends who tried it for only a few days and were not satisfied. I suspect it is because they did no take the time to use it correctly. There is a definite learning curve with these lenses.<br>
1. Handhold only if you have bionic arms<br>
2. Use monopod and for the best, use a sturdy tripod. <br>
3. Always shoot at highest ISO for best shutter speed. Remember, on a crop sensor, it is a 900mm lens!<br>
My first photo was of a American Bison, overcast with monopod, a week after purchase<br>
The second is of a little league catcher on tripod, 100 ft away. A couple of weeks ago.</p><div></div>