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Sigma releases stabilized 18-200mm ultrazoom

Sigma's 18-200mm zoom lens, with optical stabilization to counteract camera shake, gives Canon SLRs an answer to Nikon ultrazoom.

Canon SLR (single-lens reflex) owners now have an answer to Nikon's 18-200mm ultrazoom--as long as they're willing to buy a non-Canon lens.

Sigma's image-stabilized 18-200mm ultrazoom
Sigma's image-stabilized 18-200mm ultrazoom Sigma

Japanese lensmaker Sigma this week announced it's begun selling its 18-200mm ultrazoom for Canon SLR cameras.

These lenses are flexible, but typically have lower image quality than zoom lenses with narrower ranges or "prime" lenses with a fixed focal length. They're convenient, though, and often are called "vacation lenses" because they're popular with people who don't want to carry a big, heavy bag of better lenses.

Sigma's new lens is available for Canon cameras now; later models will arrive for Nikon and Sigma's own SLR cameras.

There aren't any optical tests yet for the Sigma lens to compare it to the Nikon, but a little compare-and-contrast with the rest of the specs:

• Sigma's costs $820 compared with about $750 for Nikon's.

• Both lenses have image stabilization technology, called optical stabilization (OS) in Sigma's case and vibration reduction (VR) in Nikon's. Nikon says its second-generation technology will give four F-stops of improvement, meaning that a person who can take steady images at 1/125 second without VR can shoot at 1/8 second with it. (Even if your camera is steady, moving subjects still are blurry, though.) Sigma is mum about the gains from its OS technology.

Nikon's 18-200mm ultrazoom
Nikon's 18-200mm ultrazoom Nikon

• Both have a maximum aperture of F/3.5 at 18mm, but close down to F/5.6 at maximum extension, inflicting relatively slow shutter speeds when zoomed in all the way.

• Both are geared for SLRs with the smaller image sensor that appears on the majority of SLRs, meaning they're ill-suited for Canon's full-frame high-end SLRs or Nikon's equivalent, if they ever choose to release one.

• To counteract chromatic aberration, which causes smeary colors as different frequencies of light take different paths through lens optics, Sigma's lens has one special-low-dispersion glass element and three aspheric elements. Nikon's has two extra-low-dispersion and three aspheric elements.

• Sigma's focuses as close as 45cm (17.7 inches), compared with 50cm (19.7 inches).