At review time, the Tamron 18-270mm f/3.5-6.3 Di II VC Lens holds the world record for longest focal length range in all camera mounts it supports including Canon's APS-C mount. The 15x focal length range is, without a doubt, very impressive. It is definitely the highlight feature of this lens. Other nice Tamron 18-270 features include VC (Vibration Control), a modest size & weight and a reasonable cost.
There is no perfect lens. All lenses represent a compromise of features - size, weight, price, focal length range, image quality, autofocus performance, build quality and other features. In a lens with a super focal length range, wide open aperture image quality is usually one of these sacrifices. And this is indeed the case with the Tamron 18-270. But it is not the only weakness of this lens.
The Tamron 18-270mm f/3.5-6.3 Di II VC Lens review got off to a rough start. Canon camera and lens reviews are currently my top priority for the site, but I love evaluating the third party lenses as time permits. I had a block of time available between new Canon gear introductions and decided to try a group of super zoom lenses - including the Tamron 18-270 VC. Unfortunately, tested on two camera bodies, my first two copies of this lens had significant focus calibration problems at the wide end of the focal length range (one front-focused, one back-focused). The testing, returning and re-purchasing additional copies of this lens was time consuming, but alas, my third copy functions properly. As you probably deduced, quality control is apparently an issue for this lens.
a true all-in-one lens, the canon ef-mount 18-270mm f/3.5-6.3 di ii vc pzd from tamron is a versatile 15x zoom covering wide-angle to super telephoto fields of view within a compact form factor. maintaining image quality from wide to tele, an advanced optical design is employed with a series of aspherical and low dispersion glass elements to control a variety of aberrations in order to achieve a high degree of sharpness and clarity. a bbar coating has also been applied to individual elements in order to minimize flare and ghosting for greater contrast and color accuracy when working in strong lighting conditions. contributing to greater flexibility, vc image stabilization minimizes the appearance of camera shake to better enable handheld shooting in low-light conditions and a pzd autofocus motor affords quick and quiet focusing performance. additionally, a fluorine coating has been added to the front lens element to repel fingerprints and smudging for easier cleaning