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.
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.
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.
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).