The Tamron 18-250mm f/3.5-6.3 13.9x zoom lens 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. Weighing in at 0.99 lb., the lens is compact and light, about the same size as the 18-200mm. Attractively finished in a satiny matte black, with ribbed and rubberized zoom and focusing rings, 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.
Tested in the Pop Photo 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. The Tamron 18-250mm f/3.5-6.3 13.9x zoom lens is available in Canon AF, Nikon AF, Pentax AF, Samsung AF, Sony AF with a MSRP of $499. A Nikon mount version with a built-in autofocus motor (model A18N II) is also available.
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