Review of the Pentax 100mm f/2.8

www.pentax.co.uk This is Pentax’s longest digital macro lens offering 1:1 magnification from a minimum distance of 30.3cm. It features much the same specification as the shorter 50mm and is compatible with both digital and film SLRs, using the Pentax KAF lens mount. The SMC coating reduces surface reflections and fl are, and a lens hood is included. The nine lens elements are arranged in groups of eight, and the lens has the one-touch auto-to-manual focus seen on the 50mm version. It also has the same focus lock: once the subject is in focus you can lock the position of the lens. There’s also an aperture ring, which must be set to A in order to function with digital cameras. Pentax’s performance has been impressive and this lens continues that, with good results throughout the aperture range, and peak performance at f/5.6, before leveling to f/11 and tailing off as you approach the minimum aperture. Of the three lenses in the 100mm-plus range, Pentax produced the best sharpness throughout. Fringing at the centre of the images stayed invisible throughout the range, with minor fringing occurring at the centre from the mid apertures onwards.