Lens Test: Sony 24-70mm f/2.8 Zeiss Vario-Sonnar T* ZA SSM AF

A stand-out entry in the general-purpose, full-frame zoom category, this pro-caliber lens is everything you'd expect from a Zeiss.

The 24-70mm f/2.8 full-frame zoom is becoming the general-purpose standard for news, wedding, portrait, landscape, and event pros. (Everyone, in other words, except sports and close-up photographers.) Canon, Nikon, and Sigma all offer superb examples. Sony's outstanding new entry ($1,750, street) isn't based on any earlier Sony, Zeiss, or Konica Minolta designs, but -- as the blue logo indicates -- was codeveloped with Zeiss, and it paves the way for Sony's soon-to-be-unveiled 24MP pro flagship DSLR. This lens was introduced along with an equally beefy 70-200mm f/2.8, now the fastest zooms in the Sony catalog. Both have the near-silent Super Sonic wave focusing Motor (SSM), and aspheric and ED glass elements for better control of linear distortion and chromatic aberration, respectively. A 36-105mm equivalent on Sony's APS-C sensor cameras -- such as the Alpha 350 tested in the May 2008 issue -- the 24-70mm benefits, as does the 70-200mm, from Zeiss' T* coating for suppressing reflections and flare from internal and external sources.

HANDS ON

Mostly metal construction (except for the felt-flocked, polycarb lenshood and outer barrel) and that bright f/2.8 maximum aperture make for a large, heavy lens that weighs almost 10 ounces more than the comparable Sigma. Its handsome, matte-black finish and finely ribbed focus and zoom rings are signature Zeiss.

The manual-focusing ring's turning action is near-perfectly damped, though the zoom ring turns with a slight stiffness. AF action on our test camera, the Alpha 700, was rapid, sure, and -- thanks to the SSM -- practically silent. The side-mounted AF/MF switch is the largest and most easily operable of its type, at least that we've encountered. At 24mm, the lens cast a sliver of a shadow when used with the A700's built-in flash.

IN THE LAB

Not surprisingly for a Zeiss, sharpness and contrast scored in the SQF Excellent range. In DxO Analyzer 3.1 assessments of distortion control, we found only Slight barrel at 24mm (0.30%) and Imperceptible pincushion distortion at 50mm and 70mm (0.05 and 0.08%, respectively). Nada for light falloff at any tested focal length. And at the uniform close-focusing distance of approximately 13 inches, maximum magnification ratios ranged from 1:8.14 at 24mm to a strong 1:3.56 at 70mm.

CONCLUSIONS

Because this is a full-frame lens tested with an APS-sized sensor, we can't give the stellar distortion and light falloff results too much weight. (When Sony introduces its full-frame Alpha, we'll retest for distortion and light falloff.) That said, however, the lens' superior sharpness, extremely rugged construction, and satisfying macro performance all add up to an undeniable best-in-class showing for this impressive offspring of German and Japanese manufacturing know-how.

SPECIFICATIONS

24-70mm (24.61-68.24mm tested), f/2.8 (f/2.82-2.92 tested), 17 elements in 13 groups. Focusing turns 90 degrees counterclockwise. Zoom ring turns 70 degrees counterclockwise. Focal lengths marked at 24-, 35-, 50-, and 70mm.

• Diagonal view angle: 84-34 degrees.

• Weight: 2.16 lb.

• Filter size: 77mm.

• Mounts: Konica Minolta Digital AF, Sony AF.

• Included: Lenshood, soft lens case.

• Street price: $1,750.

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