Summary: To start, I tested this lens on a Nikon D800 body, ISO 200, Induro Tripod with PHQ-1 Pan Head, and remote shutter release with mirror up. I just received this lens yesterday from Amazon. I shot at f/2.8, f/4, f/5.6, f/8, f/11, f/16 and f/22 on aperture priority.
Summary: I ordered this lens as a cheaper alternative to the Nikon 70-200 VRII. Pros: - Very well built! - Detachable tripod mount. - OS is very close to VRII in terms of functionality. - HSM II AF Motor is surprisingly quick! - Bokeh is decent (high-contrast backgrounds make the bokeh look nervous though).
Summary: It's a GOOD LENS for the PRICE.... HOWEVER, Autofocusing isn't perfect. If you're a photographer who shoots alot of sports events, and you have to rely on using Autofocusing most of the time... this isn't the lens for you. It tends to focus in front of the subject and not "ON" the subject.
Summary: This lens is built really well and looks sweet on your camera but the performance is not up to par with the price tag. The main problem I had was the quality of the pictures, most of them would come out fairly soft even if it was on a tripod.
Summary: I ended up buying this lens used on eBay. I did get it used, initially, from Amazon, fulfilled by Amazon, and said to be in great condition. I got the lens, put it on my camera, and it would not focus. Just a "ugn, ugn ugn" sound and no change in focus.
Summary: At this point, almost every lens I own is a Sigma, the only exception being my Tamron 17-50 2.8 (which is a very, very solid lens). I've owned the Sigma 120-300 2.8 for a handful of days (the best lens I've used), and the Nikkor 70-200 2.8 VR.
Summary: Couldn't wait for it to come in the mail. Sigma is a good brand, but I got a 'lemon' :( It was soft at many different apertures; I just couldn't believe it. I took many pictures in many different lighting conditions, and all were quite soft.