Olympus M.Zuiko Digital ED 12mm f2.0 (Part 2) - Technical data, How lenses are tested

Technical data

Model: M.Zuiko Digital ED 12mm f2.0

Price: $1,110

Web: www.olympus.co

Phone: 0800 1114 888

Elements/construction: 11/8

Angle of view: 84 degrees

Max aperture: f2.0

Min aperture: f22

Min focus distance: 0.2m

Mount: Micro four thirds

Filter size: 46mm

Length: 56mm

Diameter: 43mm

Weight: 130g

Features

Taken wih Olympus M.Zuiko Digital ED 12mm f2.0 lens on Panasonic

Definition

Central definition is excellent throughout the aperture range (with the exception of diffraction from f8), however the outer field falls some way behind in fine detail.

Distortion

A good deal of the 12mm’s distortion is corrected in-camera (on both JPEGs and RAW files) but there’s still a little curvature in the upper window frame.

Flare

The 12mm handles veiling glare (flare) pretty well but it’s not totally immune, and if the sun strikes the front element obliquely ghosting can be seen.

DOF scale

The 12mm is unique among MFT lenses for its maximum aperture and for its DOF scale focusing, shown here with the focus ring in its rear position.

Hood

Even at this price the 12mm doesn’t come with a hood. At around $90 the metal LH-48 is a costly and rather bulky option, but you’d be well advised to consider it.

Chromatic aberration

Some fringing and lateral chromatic aberration is visible at the edges of the frame but levels are low and can be easily removed.

How lenses are tested

Test results – tested on a Panasonic DMC-GH2, mounted on a tripod, shooting max-quality JPEG at ISO 160

We use an image-analysis application called Imatest Pro (www.imatest.com) to test the resolution of lenses. Photos of specially designed test charts are taken in controlled and consistent conditions at a range of focal lengths and apertures. These are analysed for sharpness at the centre and edge. The average of these two figures is used for the final resolution figure.

Resolution is quoted in ‘line widths/picture height’, which is the number of lines that can be resolved within the height of the picture. This is different to ‘lines per millimetre’ figures, because they only apply to a single negative size/format (typically 35mm). Digital camerashas different sensor sizes, which mean different enlargement ratios for prints and hence different ‘Imp’ requirements for lenses. Line widths/picture height measurements sidestep this and relate resolution to the final image instead.

Lenses don’t just ‘stop’ resolving progressively finer detail – they resolve it at lower and lower contrast. In the past, photographers have disagreed about when detail becomes too ‘soft’ to count. Imatest gets round this by using modulation transfer frequency (MTF) analysis and can define a cut-off point for resolution. This is called ‘MTF50’, or the point where the contrast falls to 50%.

The resolution figures are also dependent on the camera used. Different SLRs have different resolutions, different strength low-pass (anti-moire) filters over the sensor and different processing and sharpening algorithms. The same lens tested on different cameras will yield different results.

Verdict Feature: The f2.0 maximum aperture makes this lens unique with this angle of view in the MFT lens lineup. This is the first to offer DOF scale focusing and it’s both exceptionally small and reasonably lightweight Build quality: Build quality is hard to fault. The aluminium alloy barrel feels durable and the focusing and zooming are internal, so there’s no extending inner barrels Performance: AF focus operation is both swift and accurate, and it’s also near silent. The 0.2m minimum focus distance offers reasonable close-up capability at this focal length Quality of results: Attractive colour and drawing style goes some way to offset the slightly disappointing edge performance. Barrel distortion is mostly removed by software but there’s a little chromatic aberration Value for money: Olympus promotes this as a premium-quality wide-angle and while there’s a lot to like about this lens the price may be stretching it a bit considering the outer field definition and lack of either a bundled hood or case Score: As the most expensive Olympus MFT lens yet, its edge performance isn’t great but it will appeal to available-light shooters.