Sigma 60mm F2.8 DN lens
This lens comes in mounts for micro four-thirds and Sony's NEX cameras. For micro four-thirds, the effective 35-millimetre equivalent focal length is 120 millimetres and for the Sony cameras it is 90 millimetres. The appearance of the lens is unusual, with its wide, smooth barrel, which is the manual focus ring. Construction is excellent, incorporating a metal mount, which is unexpected at this price. The linear autofocus motor that shifts lens elements without the need for gearing is smooth, fast and totally silent, making it ideal for shooting video. Sigma says the closest focusing distance is 50 centimetres.
Advertisement Tested on an Olympus E-M5, it is mechanically and optically superb. As a portrait lens it is peerless, with outstanding sharpness and lovely out-of-focus backgrounds (bokeh), a benefit of the reasonably fast f2.8 maximum aperture.
The manual focus ring, although smooth and well damped, has the annoying characteristic, common in focus-by-wire lenses, of having no near and far-stop points. It just keeps turning.
This is an outstanding prime lens for a remarkably low price. The construction quality is excellent, though does seem to be susceptible to surface scratches. There is a black finish alternative. For another $340 the Olympus 60-millimetre offers 1:1 macro focus but unless you need to photograph very small objects, it is not real competition for the Sigma.