With a hefty price tag, the Pentax ultra-wide angle lens will need to pull out all the stops to impress.
Costing £949, the Pentax needs to deliver something pretty special to justify its price. Build quality certainly feels very robust and rugged, but the lens lacks the quiet autofocus supplied by the Canon USM, Nikon AF-S and Sigma USM Systems.
The lens is still pretty quick, and offers full-time manual focus override, but even the Olympus 9-18mm lens manages this trick, and the Pentax autofocus is much noisier.
More disappointment comes with the outright wide-angle ability of the lens which, taking the Pentax 1.5x crop factor into account, only equates to 18mm. The difference between this and, for example, a focal length equivalent of 15mm on other camera and lens combinations might not sound much but its very noticeable – you can squeeze much less into the frame in practical terms. All things considered, the Pentax didn’t do nearly enough to justify its price tag.
Despite the inclusion of an ED element, the contrast proved average in our tests. Colour fringing was noticeable around high-contrast edges in images – not only in the corners and edges of the frame but also towards the centre. Sharpness was impressive at apertures of f/8 or smaller but, shooting wide open at f/4, images were quite soft.