The Olympus M.Zuiko ED 12-200mm F3.5-6.3 ($899.99) is one of the longest all-in-one zooms you can get for a Micro Four Thirds camera. It covers a wide angle through an extreme telephoto view, and is protected against dust and splashes, making it an appealing lens for travel and hikes. But its optics are underwhelming, especially when zoomed in, and the lens relies on in-camera stabilization.

Big Zoom Power

Despite offering a larger zoom ratio than any other lens for the Micro Four Thirds system, the ED 12-200mm isn't overly bulky or heavy. It measures 3.9 by 3.1 inches (HD), weighs about a pound, and supports 72mm front filters. It telescopes when zoomed, just about doubling in length at full extension.

The barrel is sturdy composite with a black finish. The zoom ring takes up most of its area; it has a textured finish, so it's comfortable to grip, even if you're wearing gloves. The 12, 25, 45, 70, 100, and 200mm settings are marked, but there's no lock to keep it in place.

It's a Micro Four Thirds lens, so it can be used with compatible cameras from Olympus, Panasonic, and a few others. At the 12mm setting you'll get images with a very wide-angle view (similar to 24mm on a full-frame camera), and when zoomed all the way in to 200mm, distant subjects are brought into close view. It's a good focal range for the zoo or a national park.

The white speck near the center of the 12mm shot above is an egret; the 200mm sample shows you how much closer the lens gets when zoomed all the way in.

The manual focus ring is just ahead, at the front of the outer, nonmoving section of the barrel. It turns freely and smoothly. The manual focus experience isn't spectacular—it's responsive, but difficult to make very fine adjustments, and there's no tactile feedback. Autofocus is quick and silent, though, and most people who buy this lens will rely on it.

The macro capability is pretty good. At 12mm it focuses almost right up to the front element, though the wide angle limits the macro magnification. When zoomed all the way in, it's good for subjects as close as 8.7 inches for 1:2.8 life-size projection.

Resolution Disappoints

I tested the 12-100mm along with the E-M1 Mark II in the lab and field, and also used it a bit with the E-M5 Mark III, both 20MP cameras.

Imatest shows excellent resolution through most of the frame at 12mm f/3.5 (2,440 lines), but details get soft toward the edges. There's a slight improvement at f/4, but you'll want to use an f-stop from f/5.6 through f/11 for the best edge-to-edge resolution. Diffraction softens everything at narrower settings—avoid using the lens at f/16 (1,800 lines) and f/22 (1,100 lines) for the best results.

The aperture drops to f/4.7 by the 25mm setting, but resolution holds up, netting good resolution wide open (2,195 lines). It crosses into very good territory at f/5.6, and is excellent at f/8 and f/11. We see the expected drop at f/16 and f/22.

Image quality shows its first signs of decline at 50mm f/5.7, where it's just okay (1,960 lines). We consider it good at f/8 (2,090 lines) and very good at f/11 (2,250 lines). Again, try to avoid shooting at f/16 and f/22.

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Things fall apart at 100mm. The lens delivers soft results at f/6.2 (1,266 lines), and isn't that much better at f/8 (1,492 lines). It's improved at f/11 (1,851 lines), and because wide-open performance is so disappointing, also at f/16 (1,800 lines) and f/22 (1,345 lines).

Numbers are down a little bit more at 200mm, with the lens never crossing the 1,800-line threshold we look to as a bar for minimal acceptable resolution for a 20MP sensor. It's very soft at f/6.3 (1,170 lines) and f/8 (1,250 lines), and a little better at f/11 (1,405 lines), f/16 (1,655 lines), and f/22 (1,275 lines).

Distortion isn't a concern, nor is there a visible vignette. In-camera corrections are applied to both JPG and Raw images, but you don't have to do anything to activate them, at least if you use Lightroom for processing.

The 12-200mm doesn't have its own stabilization system. When paired with an Olympus camera with five-axis sensor stabilzation, like the E-M5 and E-M1 series, long handheld exposures are possible at the wide angle. Olympus' in-camera stabilization is very good, netting handheld shots at 1-second exposures consistently at 12mm.

At 200mm, I found 1/30-second to be the longest speed I could get away with, a speed at where subject motion is as likely to add blur as camera shake. What's disconcerting is that sensor stabilization doesn't kick in until you engage autofocus—so you'll have a shaky viewfinder experience when framing shots at full zoom.

A Story of Compromises

The Olympus M.Zuiko ED 12-200mm F3.5-6.3 has plenty of zoom power, capturing scenes at wide angles and zooming far enough to bring distant subjects into close view. If you're going on vacation and don't want to fret about lens changes there's some appeal, but beyond that, it's worth thinking of alternatives.

Olympus sells an excellent travel zoom with a shorter range, the M.Zuiko ED 12-100mm F4.0 IS PRO, but it's priced about $400 higher. You'll lose some zoom range, but you'll gain the benefits of in-lens stabilization and better image quality throughout its entire range.

If you're shopping on a budget, the M.Zuiko ED 14-150mm F4.0-5.6 II is priced at $600, but often sells for less. It's not a stellar performer, making its own compromises, but it includes weather protection, a plus for E-M5 and E-M1 owners.