Lenses are arguably the most important things in your camera bag, and they're often the most expensive. Let's face it, good glass can cost mega-bucks especially if you choose to go with lenses that carry the same brand name (Canon, Nikon, etc.) as your camera body. But if you delve into third-party lenses and don't mind skimping—only slightly—on quality, you can find some terrific bargains from Tamron, Sigma and other manufacturers.

In terms of a workhorse focal length, there are few photographers who wouldn't be caught dead without a quality 24-70mm f/2.8 lens in their camera bags. Nikon and Canon models in this focal length/aperture will set you back about $1,500 or higher. In contrast, Sigma's new 24-70mm f/2.8 IF EX DG HSM has a street price of just under $900.

Is it as good as comparable models from Nikon and Canon? Not quite but it comes pretty close. We liked the shorter—when retracted—size of the 24-70mm f/2.8 along with its sturdy, stubby build. There are two nice, rubberized grips on the barrel of the lens for adjusting the focal length and for manual focusing. Otherwise, its matte black finish looks attractive and more high-end than its price tag would suggest.

Focusing is fast and quiet on this lens thanks to the HSM (Hyper Sonic Motor) which is a great feature to have at this price point. We also liked having nine rounded aperture blades in the lens which produced excellent bokeh in our portraits.

The ELD (Extraordinary Low Dispersion), two SLD (Special Low Dispersion) glass elements and three Aspherical lenses helped prevent against distortions and chromatic aberrations while Super Multi Layer Coating reduced flare and ghosting in most but not all our images in a variety of shooting conditions during our testing.

Sharpness at the widest focal length was spot-on though we noticed some blur when we zoomed all the way in, especially when shooting in mixed lighting. Again, it's not quite as good as its Nikon and Canon counterparts, but not bad overall and a good bargain if you're a photographer on a budget.

The Sigma 24-70mm f/2.8 IF EX DG HSM is available in Sigma, Canon, Nikon, Sony and Pentax mounts.

Cost: $900 Further information: www.sigmaphoto.com