Olympus 17mm f/2.8 M.Zuiko Digital

SLRgear Review
July 13, 2009
by Andrew Alexander

One of the smallest lenses we've had in the lab, the tiny 17mm ƒ/2.8 pancake lens weighs in at just 71 grams (2.5 oz). Introduced in June 2009 with the E-P1 micro four-thirds mount camera, the lens provides an equivalent field of view of 35mm (taking into account the camera's 2x ''crop factor'').

The lens takes 37mm filters and is expected to be available in July 2009 with an approximately price of $300. The lens is also available in a kit configuration with the E-P1.

Sharpness
The 17mm ƒ/2.8 is a fairly sharp lens wide open at ƒ/2.8, though its optimal results for sharpness are achieved at ƒ/5.6.

At ƒ/2.8, we note a small central area of sharpness (~1.5 blur units) offset by some corner softness (on average, 3 blur units). Stopping down improves image sharpness: at ƒ/4, central sharpness improves slightly, and corner softness is essentially eliminated. Things become marginally better at ƒ/5.6, but you probably won't notice a difference between ƒ/4 and ƒ/5.6, so you might as well use it at ƒ/4.

Diffraction limiting begins to set in at ƒ/8, but again the impact is negligible. At ƒ/8 we note about 2 blur units on average across the frame, with a small central area of sharpness in the range of 1.5 blur units. Stopping down to ƒ/11 degrades image sharpness very slightly, and by ƒ/16 we note 3 blur units across the frame. Fully stopped-down at ƒ/22, things are fairly soft, at 4-5 blur units across the frame.

In summary, very good performance wide open and stopped-down slightly.

Chromatic Aberration
Chromatic aberration is fairly high for this lens, but fortunately the worst results are seen progressively as the lens is stopped down to its smaller aperture settings. Interestingly, the central region is both the sharpest and least impacted by chromatic aberrations, but anything approaching the corners shows off some level of fringing. Looking at our sample images is the best indication of this level of performance.

Shading (''Vignetting'')
The 17mm ƒ/2.8 does produce some light corner shading which never really goes away - fortunately, it's not overly objectionable. At ƒ/2.8 we note corners that are a half-stop darker than the center. Stopping down to ƒ/4 or less reduces this corner shading to just under a 1/3 EV differential, but it doesn't drop below the quarter-stop level.

Distortion
There is a bit of barrel distortion present in images produced with this lens - +0.2% throughout the image, and just over +0.4% in the corners. Fortunately this is easily correctable in image post-processing software, if you need your straight lines to be truly straight.

Autofocus Operation
The E-P1 uses a contrast autofocus technique, which while slow in the past on consumer point-and-shoot cameras is very speedy in the micro four-thirds configuration. The lens focused quite quickly, going from infinity to minimum close-focus in less than a second. The lens is extremely quiet in its focusing action.

Macro
While the lens focuses quite close (20cm, 8 inches) its maximum magnification is just 0.11x, making it a mediocre macro lens.

Build Quality and Handling
If you haven't already gotten a sense that this is a tiny lens, you'll have to see one to appreciate it; the E-P1 / 17mm ƒ/2.8 combination is small enough to slip into a (large) pocket, though at almost a pound in weight you may find your pants hanging a bit low on one side. The low weight is achieved through plastic construction, though the lens mount is metal. The short (22mm) barrel is finished with a matte silver, the front of the lens ringed with a blue band; the front is a charcoal-black, and the front filter threads take 37mm filters.

There are no control switches on the lens other than the focus ring; as well, there is no distance scale or depth-of-field scale. However on a lens of this size it's questionable whether either would be very useful. Functions such as autofocus control are switched via the body.

The focus ring is a 3/8''-wide plastic band, with raised indents. The ring has no hard stops, and will turn forever in either direction. There is some slight lens extension during focus operation, and the front element doesn't rotate. Without a distance scale or hard stops, it's hard to assess just how much ring travel is available. What we can say is that the E-P1 manual focus concept is very usable, in that when the lens is focused manually the LCD magnifies automatically to 100%, to allow the user to achieve excellent manual focus results.

The lens doesn't seem to ship with a hood. An interesting accessory that is available is the VF-1 viewfinder (included in the E-P1 body/lens kit). While the E-P1 concept abandons the idea of an optical viewfinder, the VF-1 re-enables it by slipping into the flash hotshoe and providing a 17mm field of view for image composition.

Alternatives

It's still early days for the micro four-thirds mount, and as such there really isn't much in the fast, wide prime category in terms of alternatives. All of our listed alternatives would require the MMF-1 four-thirds lens to micro four-thirds mount adapter. We haven't actually tested any of these combinations, so take these alternative recommendations with a grain of salt.

Olympus 25mm ƒ/2.8 Zuiko Digital ~$230
The ''regular'' pancake lens was obviously the inspiration for the 17mm pancake. The 25mm ƒ/2.8 is slightly sharper, CA is noticeably better, though there is slightly more corner shading and distortion. Slightly cheaper than the 17mm pancake.

Panasonic 25mm ƒ/1.4 ASPH Leica D SUMMILUX ~$800
We haven't yet tested this Panasonic lens, though with its fast ƒ/1.4 aperture it would make a great low-light camera combination with the E-P1.

Olympus 12-60mm ƒ/2.8-4 ED SWD ~$950
While it's not a prime lens, the 12-60mm ƒ/2.8-4 offers very fast performance at the 17mm mark (it's maximum aperture at 17mm is approximately ƒ/3). The lens is sharper and produces slightly less CA, but has slightly more corner shading and more complicated distortion than the 17mm prime. It's also much more expensive, and would hang quite heavy on the E-P1.

Conclusion
Optically, the lens performs well, though not exceptionally: it's reasonably sharp wide open, though best used at ƒ/4, and chromatic aberration is higher than we'd like. Distortion and corner shading are very reasonable. In terms of sheer portability, it's hard to beat the E-P1 with the 17mm lens mounted, as it's lighter than some advanced point-and-shoots. The low price tag also makes it fairly attractive, though it's a lens you may want to keep away from the sofa: it's so small, it could get lost in the cushions.

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.