Sigma’s newest lens the 17-50 f2.8 followed by acronym hell is now available. Let’s break down those acronyms and features EX – A nicer fit and finish on the exterior of the lens. Sigma uses the word Superior. DC – Designed for smaller, crop-sized sensors OS – Optical Stabilization, Canon calls it IS – image stabilization and Nikon uses the acronym VR – vibration reduction. Tiny gyroscopes in the lens allow you to shoot at slower shutter speeds without getting blur from shake or handshake. HSM – Hyper Sonic Motor, Canon uses the acronym USM- ultra sonic motor and Nikon uses the acronym SWM – silent wave motor. It all translates to fast and quiet auto focus. A longer post is in the works discussing the pros and cons of buying 3rd party lenses, namely Sigma and Tamron, versus the ones made by Canon and Nikon but in the short term I will say that recent Sigma lenses have been excellent and they seem to be doing a much better job of quality control. The more important question you may be wondering is why would or should someone shell out ~$670 for a lens that offers a very similar range to the kit lens included with entry level DSLRs from Canon and Nikon. Not enough reviews are in for me to recommend this lens yet but I will share with you what it is offering over the kit, which it really isn’t designed to compete with. It is designed to compete with Canon EF-S 17-55mm f/2.8 IS USM Lens for Canon DSLR Cameras and Nikon 24-70mm f/2.8G ED AF-S Nikkor Wide Angle Zoom Lens both of which are over $1000. The Sigma has a constant aperture of f/2.8 as do both of the lenses linked above, this combined with the OS provides the potential for excellent low light shots. Once the lab tests come in I will update this post with comparissons to the two lenses above, but at a savings of $400 and nearly $900 respectively it would be might tempting for anyone needing a fast, low light lens. And because it is optimized for crop sensor cameras it is fairly compact.  One final note – those using DSLRs for video should give this a long look – again the OS combined with f/2.8  gives you a smooth lowlight lens. Buy on Amazon