Summary: Great walk around lens. Prevents the need to switch lenses in the field and avoids getting dust inside the camera. But... The amount of light coming in especially at long focal length is much less than the Nikon kit lens (70-200). It has a very difficult time focusing on moving subjects even when they are not moving fast and even with lots of light available. I've noticed some amount of flaws in the edge of most pictures at a variety of focal lengths.
Bulky but a suitable one lens solution for DSLR owner
11 July 2013
Summary: Sold my DC 18-200mm with 62mm filter size for this slightly longer focal OS lens...sad to say I'm not accustomed to using a much larger diameter (72mm) grip and heavier lens. The extra 50mm on the long end is not worth the bulk - the OS is nice to have but if you have a steady hand or use a tripod, you won't need this feature.
Summary: I bought this lens because of its high-power zoom and silent HSM focusing system. The image quality is not bad at all and silent and fast HSM is very satisfactory. The problem is its size and weight. It's a little too big and heavy to carry. This lens may be already outdated and isn't worth what you will pay for it.
Summary: This is the second Sigma lens I have purchased, and it is the second one I have had a problem with within a short period of time after receiving it. My first one was the Sigma 18-200 OS for Nikon. That lens did not connect with my D90 properly, so I had to send it to Sigma for repair. After repair, the lens worked great, and I really liked it. Check out dpreview[@]for a full review of some of its pros and cons.
Summary: My first Sigma lens...Previously, I have bought all Sony lenses for my Alpha 100 and now 700. I like this lens as an overall utility lens. It takes a while to focus and really eats away at the battery though. That is my one big negative for this lens.
Pros: Easily Interchangeable, Rugged, Sharp Focus, Strong Construction
Summary: Great image result for an APS-C style of camera. Used extensively on a major holiday in Europe the lens proved itself. The only downside is 'lens creep' as set in and the 'lock' must be placed on at all times if the camera is facing towards the ground when being carried. Disappointing for a lens that is less then 6 months old.
Sigma is getting there with quality but, improvements are required.