Sigma 120-400mm f/4.5-5.6 DG OS HSM: Lens Test

Clearly a sibling to Sigma's larger 150-500mm f/5-6.3 OS lens, this full-frame tele zoom ($850, street) is almost the mirror image of that longer lens, but about 25 percent smaller. It replaces Sigma's 135-400mm f/4.5-5.6 in the lineup, and it's a significant upgrade for a number of reasons: It uses Sigma's silent HSM focusing motor, is compatible with Sigma teleconverters, and, of course, includes Sigma's Optical Stabilizer. An 186-620mm equivalent when mounted on most DSLRs (that's 372-1240mm -- albeit without AF -- when used with a 2X teleconverter!), this lens incorporates three elements of super-low-dispersion glass for sharpness and is sold with hood, case, and a pretty cool tripod collar.

HANDS ON

The finish is Sigma's new ultra matte-black coat. Almost velvet-like, the surface looks prone to scuffing, but won't scratch (in normal use). Although the removable tripod collar is relatively large, it's cleverly designed with finger channels to help it double as an excellent grip for off-tripod shooting, even a good carrying handle for the lens and camera rig.

At 8.12 inches at its most compact, it's a big lens, but you can handhold its 3 pounds and 12-plus ounces easily due to smart positioning of zoom and focusing rings, and a pleasing balance overall.

The AF is near-silent thanks to the HSM AF motor -- and by the standards of such a long zoom, it's fast-focusing. In field tests, the AF system had no problem latching onto and following approaching cars, bicyclists, even pigeons. We suspect it would do well from gridiron sidelines or at waterside tracking soaring ospreys.

The amply sized zoom ring is somewhat stiff turning, but the smaller, well-placed manual-focus collar is nicely damped and a pleasure to use. Manual focus is possible in the lens' AF mode. Its barrel houses well-marked switches for AF/MF, the OS modes (on, off, and panning), plus a zoom lock at 120mm.

Julia Silber


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