Olympus 9-18mm f/4-5.6 ED M.Zuiko Digital

SLRgear Review
May 3, 2010
by Andrew Alexander

This is the third M.Zuiko series lens we have tested, the first being Olympus' diminutive 17mm prime. The M.Zuiko lens series is designed specifically for Olympus' PEN series of digital interchangeable lens bodies.

The 9-18mm ƒ/4-5.6 lens uses some revolutionary components, including a new lens element called a ''Dual-sided Super Aspherical'' lens. The lens element has a remarkable shape and must require some pretty amazing moulds to make. In addition, the lens is designed with video in mind, using a new silent autofocus motor.

The lens is designed for the four-thirds sensor system, meaning it will provide an effective field of view of 18-36mm (a 2x ''crop factor''). The lens is compatible with regular four-thirds camera bodies via an adapter. This lens isn't a "constant" lens, in that as you increase the focal length, the maximum aperture size decreases, though the minimum aperture size remains the same. The following table reflects the changes as you zoom:

The lens is slated to be available in May 2010, and should retail for approximately $700. It's unclear whether the lens ships with its unusual square-cut lens hood (LH-55B). The lens takes 52mm filters.

Sharpness
When used wide open (ƒ/4-5.6) the Olympus 9-18mm M.Zuiko provides nicely sharp results in the central portion of the frame, in the range of 1.5-2 blur units. There is some light corner softness, most noticeable at 9mm and 11mm: at the extreme, it's 6 blur units at the top right at 9mm. On the average, it's around 2-3 blur units in the corners.

Stopping down improves both central and corner sharpness; it's still sharper in the center, but now we see results between 1-2 blur units across the frame. Stopping down further doesn't actually do much to improve image sharpness, and diffraction limiting sets in around ƒ/11. If I were to pick, I'd say the optimum settings for this lens are 9mm and ƒ/5.6.

Fully stopped-down, the lens provides average performance - 3-5 blur units at 9mm, but improving as it's zoomed in towards 18mm, where it shows around 3 blur units on average.

Chromatic Aberration
CA shows up substantially in the corners with this lens, though it's not noticeable in the central region of the image. According to our tests, it's at its best when the lens is used at the 9mm setting, and at its worst at 11mm and 14mm. Chromatic aberration appears as a magenta-cyan discoloration at areas of high contrast.

Shading (''Vignetting'')
Corner shading isn't really an issue with this lens, with image corners exposing a quarter-stop darker than the center of the image at all focal lengths and apertures, with one exception; used at 9mm and ƒ/4, the corners are a half-stop darker than the center.

Distortion
It's not surprising to see a fairly high level of distortion in this wide angle lens, though the distortion is consistently barrel-shaped and easily correctable in post-processing software. At the widest setting (9mm) the lens shows a full 1% distortion in the corners. However, the lens is optimized nicely, and by 18mm there is very little distortion to speak of at all.

Autofocus Operation
The 9-18mm autofocuses quickly, going from closest focus to infinity in less than one second. It is virtually silent in its operation, as there is (according to the Olympus press release) only one lens element which moves to focus. Point-to-point focusing is very quick. The front element does not rotate during focus operations.

Macro
The Olympus 9-18mm M.Zuiko doesn't offer much for macro work: just 0.1x magnification, and a minimum close-focusing range of 25cm (around 9 inches).

Build Quality and Handling
The Olympus 9-18mm ƒ/4-5.6 M.Zuiko redefines the word tiny, at around 2 inches in both length and diameter. The lens doesn't weigh much either, at just 5.5 oz (155 grams). It uses plastic construction to achieve this weight savings, its exterior a matte black finish. The lens mount is metal, and the 52mm filter threads are plastic. The lens does not have a distance scale or depth of field markings, and there is only one switch, which locks the lens in its open position.

The last remark requires a bit more description. To make the PEN camera even more compact, the designers engineered a zoom lens system that retracts the body of the lens into itself for storage. However, to keep the mechanism from retracting fully as you move from the 18 to 9mm position, there's a lock to limit its travel. This slider must be released for the lens to collapse back into the fully retracted position.

The zoom ring of the lens is plastic with raised ribs, about a half-inch wide. The ring takes about 45 degrees to move through its range of focal lengths, as well there is a bit of extra play for retracting the lens into its storage state. There is some lens extension with this lens - it's at its longest at 9mm, extending an additional 1.25 outward, and then retracting as the lens is zoomed in to 18mm. With a lens this small, zoom creep is not a factor; there is a zoom lock switch, but it doesn't operate as you'd expect, locking the zoom into a storage state. The camera will not operate with the lens in its locked position; see above.

The focusing ring of the lens is an ndented ribbed plastic just 3/16 inch wide. The ring uses a ''fly-by-wire'' system to achieve manual focus results, and the E-P1 provides some interesting manual focus functionality. When you turn the focus ring with the MF assist option on, the camera brings up a magnified center view to allow you to precisely focus. The ring will turn forever, as there are no hard or soft stops in the focus ring, and there's no way to know how many ''degrees'' of turning action are available. The fly-by-wire operation does allow for an interesting option: you can set the focus ring direction to either left or right, from the camera's menu.

At the time of writing it's not clear whether or not the 9-18mm ƒ/4-5.6 M.Zuiko ships with its interesting LH-55B lens hood; we didn't get one with the sample we tested. The lens is a rectangular-shaped hood, which attaches via a bayonet mount.

Alternatives

Olympus 9-18mm ƒ/4-5.6 ED Zuiko Digital ~$500
While we haven't yet tested this lens, the most obvious alternative would be the non-M Zuiko equivalent of this lens design, which can be used on the PEN series of camera with an adapter. However, it's twice as heavy and slightly longer and wider. For the price premium, you're getting the storage functionality of the M.Zuiko.

Olympus 7-14mm ƒ/4 Zuiko Digital ~$1,500
If wide-angle is your goal, then this is the lens that would let you do it on a PEN series camera - offering a 14-28mm equivalent field of view. We haven't yet tested this lens, though it has received raves in our user reviews. With an adapter it would be usable on a PEN series camera, though at 27 ounces, the lens is over two times as heavy as the camera, which could make for some awkward usage.

Panasonic 7-14mm ƒ/4 ASPH LUMIX G VARIO ~$1,000
The Panasonic 7-14mm ƒ/4 is compatible with the Olympus PEN series of camera, and compared to the Olympus 9-18mm, the lens is sharper, provides better results for chromatic aberration, and less distortion. The Panasonic lens is more expensive, larger, and doesn't store like the Olympus, however.

Sigma 10-20mm ƒ/4-5.6 EX DC HSM ~$480
With an adapter, the four-thirds mount version of the Sigma 10-20mm ƒ/4-5.6 (or the newer ƒ/3.5 version) should be compatible with the PEN series of camera, and while we've tested it, you'll have to use your imagination on our test graph to compare its performance with the Olympus 9-18mm. The lens is less expensive, and would provide an equivalent field of view of 20-40mm, though it would be heavier than the camera itself, making for a potentially unwieldy combination of lens and camera.

Conclusion
For its size, the Olympus 9-18mm ƒ/4-5.6 provides impressive performance. While there are other lenses which provide similar or better performance, none offer the diminutive size and storage functionality of the 9-18mm M.Zuiko. While the retracting lens function may take some getting used to for some, it's hard to believe that this is a camera system that you can carry around in your pants pockets.

Sample Photos

The VFA target should give you a good idea of sharpness in the center and corners, as well as some idea of the extent of barrel or pincushion distortion and chromatic aberration, while the Still Life subject may help in judging contrast and color. We shoot both images using the default JPEG settings and manual white balance of our test bodies, so the images should be quite consistent from lens to lens.

Still Life shot

VFA target

As appropriate, we shoot these with both full-frame and sub-frame bodies, at a range of focal lengths, and at both maximum aperture and ƒ/8. For the ''VFA'' target (the viewfinder accuracy target from Imaging Resource), we also provide sample crops from the center and upper-left corner of each shot, so you can quickly get a sense of relative sharpness, without having to download and inspect the full-res images. To avoid space limitations with the layout of our review pages, indexes to the test shots launch in separate windows.