Much bigger than most lenses, and at more than twice the weight of some, the Tokina AT-X 16-28mm f/2.8 PRO FX is a chunky lens. That's because while other lenses are designed solely for use on cameras with APS-C or Four Thirds sensors, the Tokina is fully compatible with full-frame cameras.
Essentially, it's designed as a full-frame ultra-wide-angle zoom, so why would you want it on your APS-C camera?
Image quality should be excellent, because you're only using the central region of the image circle produced by the lens. And if you're thinking of upgrading to a full-frame camera in the future, the lens will still be useful.
Downsides include no image stabilisation, which is usual for ultra-wide lenses, and there's also no filter thread for attaching filters.
Autofocus is based on Tokina's new 'silent' DC motor, which proved fast, quiet and accurate, but not as quiet as the USM, AF-S and HSM competition.
There's no full-time manual override, but the lens does feature Tokina's trademark push-pull focus ring for easily switching between autofocus and manual focus.
Despite being a full-frame lens, we found a drop-off in sharpness between the centre and edges of APS-C format images. Even centre sharpness wasn't very impressive, especially at the maximum aperture of f/2.8.
As expected, vignetting was less pronounced when used on an APS-C camera, but it was still noticeable.
Most ultra-wide lenses have a filter thread for attaching filters, or at least a gel filter holder at the rear of the lens. The Tokina has neither, making the use of filters tricky.
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