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Studio Tests

Another day, another Olympus lens which is difficult to fault. Overall performance is very good, with impressive sharpness, extremely low distortion and essentially no falloff; the only minor fly in the ointment is moderately high chromatic aberration towards the corners of the frame. Impressive stuff.

Sharpness Sharpness results are impressive, with high consistency across the frame at all focal lengths, and relatively little decline in sharpness towards the corners. Best results are actually obtained wide open, with the image progressively softening due to diffraction on stopping down. As usual on Four Thirds, F16 and especially F22 are best avoided.
Chromatic Aberration Chromatic aberration is moderately high, as expected for a wideangle zoom. Red/cyan fringing is visible at all focal lengths, but at levels little worse than those found on typical standard zooms. The CA is highest at 11mm, and tends to get slightly more pronounced on stopping down (peaking at about F11). However the profiles are generally sufficiently close to linear that software correction should be relatively straightforward when required.
Falloff We consider falloff to start becoming a potential problem when the corner illumination falls to more than 1 stop below the center. The 9-18mm shows no significant falloff at all; if you happen to like vignetting, you're going to have to add it in post-processing.
Distortion Distortion is extremely low, ranging from 0.8% barrel at 9mm through to -0.3% pincushion at 18mm. In real world terms, this will to all intents and purposes be imperceptible. However for those looking for absolutely perfectly straight lines, distortion can be corrected using Olympus's free Master software.

Macro Focus

We wouldn't expect wide angle zooms to be great for macro work, and the 9-18mm meets these expectations. The measured maximum magnification is slightly higher than Olympus's specification at 0.14x, at a minimum focus distance of 22.5 cm and a working distance of 11 cm from the front of the lens to the subject.

Image quality is fair; it's a bit soft at F5.6, and best results are obtained at F8-F11. The corners of our test chart shot are still rather soft, and there's strong blue/yellow chromatic aberration.
Macro - 124 x 93 mm coverage
Distortion: Moderate barrel
Corner softness: moderate
Focal length: 18mm (36 mm equiv)

 

Specific image quality issues

As always, our studio tests are backed up by taking hundreds of photographs with the lens across a range of subjects, and examining them in detail. This allows us to confirm our studio observations, and identify any other issues which don't show up in the tests. The Olympus 9-18mm performed admirably in real-world use, turning in an excellent performance overall.

Flare

Control of flare is a critical feature of a superwide lens; with such a broad view of the world, bright light sources will find themselves in the frame on a regular basis. Overall the 9-18mm fared pretty well in this regard, showing only occasional problems with flare, most problematically with a very bright light source towards the centre of the frame.

The samples below illustrate typical everyday 'contre jour' shots. With the sun in the corner of the frame at wideangle, the lens shows few problems at typical shooting apertures, but develops distinct radial 'streaking' patterns on stopping down (as in the F16 example shown here). Zooming in to 18mm with the sun still impinging directly on the front of the lens, we see some flare patterns and a loss of contrast towards the top left of the frame; in such situations it would be advisable to provide additional shading to the front element beyond that already offered by the hood.

9mm F16, sun in corner of frame 18mm F5.6, strong backlight

Chromatic aberration

Wideangle zooms are bound to suffer from a degree of lateral chromatic aberration, but Olympus has managed to keep it reasonably under control in this lens. A degree of red/cyan fringing is visible at all focal lengths, and the samples below give an idea of what to expect. The CA is reasonably straightforward to treat in post-processing; the crops at the bottom illustrate a 'quick and dirty' application of Photoshop CS3's 'lens correction' filter to the out-of-camera JPEGs, resulting in substantial (if not complete) removal of the fringing. Better results could be obtained from applying the correction during RAW conversion.

9mm
12mm
F5.6, Olympus E-3 F8, Olympus E-30
100% crop, upper left 100% crop, lower left
Red/cyan correction +9 in PS CS3 Red/cyan correction +8 in PS CS3

Distortion correction using Olympus Master

The 9-18mm shows extremely low distortion which will only rarely be visible in real-world shots, but for those occasions when absolutely straight lines are essential, it can be corrected using Olympus's free Master software (supplied with their cameras). The example below illustrates this in action; the original image has slight but visible barrel distortion, after running it through Olympus Master 2 this is corrected essentially perfectly, with the lines at the bottom of the picture becoming totally straight. Impressive stuff.

Olympus E-30, 9mm F8
Original Distortion corrected
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