Tamron means business with its first high-speed tele zoom in more than 10 years. This full-framer ($700, street) scales up, approximately, to a 109-310mm on most DSLRs, and as a member of Tamron's SP (Super Performance) family, was designed as a pro-quality lens. It boasts two costly LD glass elements that control color fringing and coatings to suppress flare off digital sensors. The lens makes a logical mate to Tamron's 28-75mm f/2.8 SP pro zoom.
HANDS ON: At 2 pounds, 14.6 ounces (including magnesium-alloy tripod collar and reverse-stowing lenshood), the lens might seem heavy, but it's actually lighter than most in its class. (Sigma's comparable 70-200mm f/2.8, for example, weighs more than 3 pounds, including hood.) With the petal-type lenshood in place, it's almost 11 inches long. Internal-zooming (and -focusing), at least it doesn't extend past that.
Its AF action is moderately fast, moderately quiet, and sure. Both manual-focus and zoom rings are very well-damped and even-turning. Each is textured with both knurled and ribbed patterns of rubber. Nearly 2 inches wide, the manual-focusing ring is unusually large, and well-designed for quick focusing touch-ups.
While the lens doesn't allow manual focus in the AF mode, it flips between the two with unusual ease thanks to this manual-focus ring that doubles as an easy-to-use, push/pull-type AF on/off switch. Its barrel markings are a bit unusual, though. When the switch is in the MF position, the markings that show the lens' AF/MF status are concealed under the ring. Result: First-time users can spend several minutes wondering how to go from manual to AF.
IN THE LAB: As with most lenses today, it boasts sharpness and contrast in the Excellent SQF range. It performed noticeably better than the Sigma, which dipped through Very Good into the Good SQF range at 200mm. Also impressive: DxO Analyzer 3.0.1 distortion control tests, showing Slight barrel distortion at 70mm (0.23%), and Slight pincushion distortion at 135mm and 200mm (0.13% and 0.23%, respectively). This was on a par with the Sigma, and much stronger than Canon's 70-200mm f/2.8L IS, which produced Very Visible barrelling at 70mm (1.28%).
Light falloff was gone from the corners by f/3.5 at 70mm and by f/4 at 135mm and 200mm -- also noticeably better than the Sigma, which showed corner vignetting out to f/9 at 135mm.
Another Tamron forte: Maximum magnification ratios measured at uniform close-focusing distance of 37.2 inches ranged from 1:8.14 at 70mm to 1:2.85 at 200mm -- also more power than the 1:3.3 Sigma.
CONCLUSIONS: An excellent choice for wildlife, nature close-ups, and even some, not-too-fast-breaking sports, this bright, well-built lens features the highest close-up magnification in its class at, by far, the lowest price. Despite its lack of O-rings for extra dust and water resistance, the lens is good enough to leave us only one word for prospective high-speed tele zoom buyers: Pounce!
IMAGE QUALITY: Zoomed out to 188mm, with the aperture open to f/2.8, this Tamron, mounted on the Canon EOS-1Ds Mark III, nicely separates subject and background.
70-200mm (70.80-193.65mm tested), f/2.8 (f/2.88 tested), 18 elements in 13 groups. Focusing turns 90 degrees counterclockwise. Zoom ring turns 90 degrees counterclockwise. Focal lengths marked at 70-, 85-, 100-, 135-, and 200mm.
• Diagonal view angle: 34-12 degrees.
• Weight: 2.91 lb.
• Filter size: 77mm.
• Mounts: Canon AF, Nikon AF. Available soon: Pentax AF, Sony AF.
• Included: Lenshood, softcase, removeable tripod collar.
• Street price: $700.