How to zoom from 28mm to 388mm (equivalent) with a singular digital-only
While you were out, the digital-only superzoom got more super. Tamron, originator of the superzoom lens more than a decade ago, ups the ante with its new 18-250mm f/3.5-6.3 optic -- boasting the industry's broadest zoom range, at nearly 14X (13.9X). A 28-388mm equivalent, it adds 50mm to the tele end and does so at no cost of weight, dimension, or optical performance over Tamron's 18-200mm f/3.5-6.3 lens (which remains in Tamron's catalog). Only the price is higher: at $499, street, vs. $390 for the shorter lens.
Compact and light, it's about the same size as the 18-200mm. Attractively finished in a satiny matte black, with ribbed and rubberized zoom and focusing rings (the former large, the latter on the small side), the lens sports the bright gold Di II band that distinguishes all Tamron digital-only lenses.
We found its zoom action slightly uneven, somewhat stiff and overdamped, which rendered the zoom lock unnecessary. AF action was fast and quiet. On the Canon EOS Digital Rebel XTi, with the lens barrel fully extended, it cast no shadow when used with built-in flash.
In The Lab:
SQF data came in at Excellent for all focal lengths, a surprising development, considering that the 18-200mm (like most 11X superzooms) drops into the Very Good range at the long end. In DxO Analyzer 2.0 tests, we found Visible barrel distortion at 18mm (0.72%) and Slight pincushion distortion at 35mm, 100mm, and 250mm (0.18%, 0.22%, and 0.16%, respectively). These numbers are also noticeably better than the 18-200mm.
At the close-focusing distance at 250mm, we found Imperceptible barrel distortion (0.01%), suggesting an excellent lens for close-up work. Light falloff was gone from the corners by f/5.6 at 18mm, f/4 at 35mm, f/5.6 at 100mm and f/8 at 250mm (f/6.3 at close focus).
At the common close-focusing distance of approximately 16 inches, maximum magnification ratios ranged from 1:16.3 at 18mm to a very satisfying 1:3.08 at 250mm.
An impressive optical achievement, the industry's first 13.9X digital-only zoom hits a trifecta by expanding zoom range, utility, and optical performance.
18-250mm (18.52-238.11mm tested), f/3.5- 6.3 (f/3.26-6.86 tested), 16 elements in 14 groups. Focusing turns 55 degrees counterclockwise. Zoom ring turns 80 degrees counterclockwise. Focal lengths marked at 18-, 35-, 50-, 70-, 100-, 200-, and 250mm.
• Diagonal view angle: 75-6 degrees.
• Weight: 0.99 lb.
• Filter size: 62mm.
• Mounts: Canon AF, Nikon AF, Pentax AF, Samsung AF, Sony AF.
• Included: Lenshood.
• Street price: $499.