You might think an f/1.2 maximum aperture is fast – and it is on a camera with a 36 x 24 mm sensor. However, on a M4/3 camera, the crop factor of 2x causes the focal length to be equivalent to 85mm in 35mm format, while the maximum aperture admits as much light as an f/2.4 setting on the ‘full frame’ camera. It’s still pretty fast, although not as fast as the impression created by the specifications.

The optical design of the DG Nocticron 42.5mm f/1.2 ASPH consists of 14 elements in 11 groups. Two aspherical lenses are included to suppress spherical aberration and distortion. In addition one ED (Extra-low Dispersion) and one UHR (Ultra High Refractive Index) lens optimise image resolution across the frame and help to keep the overall size of the lens relatively compact for its speed. Panasonic’s Nano Surface Coating technology minimises the effects of ghosting and flare.

Nine iris diaphragm blades that close to a circular aperture ensure smooth out-of-focus areas at wide aperture settings. An aperture ring on the lens barrel allows direct control over aperture settings.

Panasonic’s POWER O.I.S. (Optical Image Stabiliser) system can compensate for both small, fast movements and large, slow movements, making it easy to obtain sharp images when shooting in poorly-lit situations. A new stepping motor makes the autofocusing action smooth and silent for both still and video recording. When the lens is mounted on Lumix G-series cameras, users can take advantage of their fast and accurate Contrast AF system.

The DG Nocticron 42.5mm f/1.2 ASPH is supplied with front and end caps, a generous cylindrical metal lens hood and a soft carrying pouch.

Who’s it for?

Optically, this lens rates among the best performers available for M4/3 cameras. For photographers who really need this performance level from a very fast lens that provides excellent depth-of-field control the asking price would probably justify the investment.

It is also among the most solidly built lenses available for the M4/3 system and comes with effective stabilisation, a pleasant-to-use aperture ring and a deep cylindrical lens hood made of sturdy metal. All contribute to making it decent value for your dollars.

If you don’t require such a fast lens and can’t afford the DG Nocticron 42.5mm f/1.2 ASPH, both Panasonic and Olympus make reasonably fast 45mm autofocusing prime lenses. At $499, the Olympus M.Zuiko Digital ED 45mm f/1.8 looks like a bargain. Its maximum aperture is about a stop slower and it relies on the body-integrated stabilisation in Olympus camera bodies (which is only replicated in Panasonic’s GX7).

Panasonic’s Leica DG Macro-Elmarit 45mm f/2.8 ASPH is two-and-a-third f-stops slower but benefits from built-in stabilisation and the ability to focus to 15 mm and provide true 1:1 reproduction. Its Australian RRP is $1099, but it’s available at less than AU$1000 if you shop around (the US list price is $900).

RRP: AU$2,299; US $1599.99