The M.Zuiko Digital 25mm F1.8 II ($499.99) updates a decade-old lens, the original Olympus M.Zuiko 25mm F1.8, with upgraded metal, weather-sealed housing, and OM System branding. Nothing else changes, though; the optics carry over, so the lens renders the same sharp photos with characterful background blur as before. The improved build is welcome for anyone with a weather-protected OM or Lumix Micro Four Thirds camera, and the 25mm F1.8 II readily softens backgrounds. We've not tested either of Panasonic's direct competitors: The Leica DG Summilux 25mm F1.4 II lens ($699.99) gathers more light and is also weather-sealed, while the Lumix G 25mm F1.7 ($249.99) is a true value option, but the M.Zuiko 25mm F1.8 II is a reliable performer on its own merits.

Design: A Featherweight Prime for Micro Four Thirds

The M.Zuiko 25mm F1.8 II is roughly the same size as the original, coming in at 1.7 by 2.3 inches (HD) and 5.5 ounces with support for 46mm filter threads. The mark II edition is a teensy bit heavier than the first 25mm F1.8 (1.6 by 2.2 inches, 4.8 ounces), which makes sense as the new lens has an aluminum barrel and IPX1 weather sealing, while the older version is made of plastic without any seals or gaskets inside.

(Credit: Jim Fisher)

The IPX1 rating is new to the 25mm F1.8 II, but lines up with OM's line of sealed cameras. If you match it with an OM-1, OM-1 Mark II, or OM-3 (all rated IP53) you can go out and make pictures in heavy precipitation if it suits your fancy. The Panasonic Leica DG Summilux also advertises dust and splash protection, though it is not officially IP rated, while the budget Lumix G 25mm F1.7 omits weather protection. There aren't many other autofocusing standard primes for the system; the Olympus M.Zuiko 25mm F1.2 Pro ($1,399.99) is the other of note, though its extra-bright optical formula makes it a pricey, bulky proposition.

OM ships the lens in basic brown cardboard, an environmentally conscious choice that enables easier recycling versus packaging with a glossy finish. The lens ships with front and rear caps and a reversible plastic hood. It's a good idea to use the hood to add some extra protection to the front element. OM does not include anti-smudge fluorine on the glass, so you'll want to take care to keep it free of water drops to avoid marks. Lenses with fluorine are easy to clean with just a microfiber cloth, while I had to reach for a wet cleaning wipe to remove a fingerprint smudge from this one.

(Credit: Jim Fisher)

Handling and Focus: Fast, Silent Focus

There's not much going on with controls for this lens, as it has a manual focus ring, and that's it. It's the same situation as with the first edition. Manual focus proves to be just a little bit easier to manage than with the wider angle M.Zuiko 17mm F1.8 II, though I'd qualify both as being a little touchy in practice. If you want better manual focus (without going for a full manual lens like the $64 TTArtisan 25mm F2), the high-end M.Zuiko 25mm F1.2 Pro includes a manual focus clutch that provides more drag for precise adjustments without sacrificing the convenience of autofocus.

(Credit: Jim Fisher)

Granted, autofocus on the M.Zuiko 25mm F1.8 II is good enough that you don't have to set things manually. Photogs who rely on autofocus will enjoy instant response from a nearly silent motor with this lens. I tried it with the OM-1 Mark II and OM-3 cameras and it snapped right into focus without hesitation with both. The lens exhibits moderate breathing when shifting focus, as the frame is slightly tighter when focused close-up versus at distance, but it's not enough to detract from focus racks that shift a viewer's attention from one subject to another.

OM advertises the lens as having a 9.8-inch (0.25m) minimum focus distance, a figure that translates to 1:8.3 life-size magnification at the nearest focus distance. The lens I reviewed focused a little bit closer than advertised, however. I used it to photograph a ruler and calculated magnification as closer to 1:6.25. I don't mind the extra, unadvertised versatility, though I will note that it's uncommon for lenses to hone in closer than the specs indicate. The OM 17mm F1.7 II shares this trait.

(Credit: Jim Fisher)

I asked a company representative about the behavior and was told that the 9.8-inch figure is one where image quality is guaranteed, and focusing closer may reduce picture quality. Either way, it's handy to be able to focus a little closer, though if you are looking for a macro lens first and foremost, opt for the M.Zuiko 30mm F3.5 Macro, which captures images at greater than life-size (1.25:1) at its nearest focus distance.

(Credit: Jim Fisher)

Image Quality: Razor-Sharp Optics, Slightly Frenetic Backgrounds

I used Imatest software to check how much detail the lens can resolve with the 20MP OM-1 Mark II in our test studio. The 25mm F1.8 II aces lab tests, burying the needle for the OM-1's sensor from f/1.8-8 (2,700-2,900 lines). It loses a little bit of detail starting at f/11 (2,550 lines) and continuing through f/16 (2,100 lines) and the minimum f/22 (1,500 lines) setting. The precipitous drop is caused by optical diffraction, an effect of physics that causes light particles to scatter apart as they pass through a small opening.

(Credit: Jim Fisher)

The lens handles flare pretty well. I shot several pictures directly into the sun, and details in the foreground held up without too much false color. I noticed a couple of instances of bright magenta reflection spots when stopping down to f/16-22, as is the case with most lenses when used at very small f-stops for this type of image. This is a good one to use for backlit photos, though I'll point out the sunstars it draws from f/11-22 are somewhat mushy and not well-defined.

There's no visible distortion of which to speak in either Raw or JPG images, as the lens draws properly straight lines, even without the aid of a correction profile. I noted a slight vignette visible at f/1.8-2 in JPGs, but it is gone starting at f/2.8.

(Credit: Jim Fisher)

The 25mm F1.8's mix of standard angle, decently close focus, and bright maximum aperture means it is inclined to snap photos with soft, defocused backgrounds. Getting bokeh in pictures and isolating a subject from the background is one of the biggest advantages you get from a wide aperture lens. Backgrounds are a little busy, however. The optics are sharp for sure, but also draw highlights with defined edges that are a little brighter than the center, along with false purple/green color shift, a form of longitudinal chromatic aberration (LoCA). It's easy to spot the LoCA around the tree branches in the background of the following image, and I noticed it in the transitory areas between focus and blur in some close-ups of flowers, too.

(Credit: Jim Fisher)

Of course, LoCA is a situational concern that won't show up in every image, but the blurred-background photos you're prone to make with a bright standard lens are likely candidates for false color. LoCA has proven problematic to remedy with software tools, so aside from making a photo black and white, there's no getting around it when it appears. It's a common issue among small Micro Four Thirds lenses, too. I also noted it in the M.Zuiko 17mm F1.8 II. While I've not tested the Leica DG 25mm F1.4 II, samples in reviews from other publications (including this one from ThePhoblographer) show similar effects.

(Credit: Jim Fisher)

Verdict: A Reliable Everyday Carry Lens, Now Sealed

There's not much new about the OM System M.Zuiko 25mm F1.8 II. The first version is a long-running, well-regarded option for the Micro Four Thirds system and is certainly up to the task of keeping pace with the resolution and speed of more recent cameras. And while we'd have certainly liked to see some tweaks to the optical formula to better suppress false color effects, the addition of weather sealing and the upgrade to a metal barrel make this edition a better fit for photogs who work in rough weather. It's a good, small, mid-price option for users who want a lens that can isolate subjects and blur backgrounds, though we give slight preference to the wider angle M.Zuiko 17mm F1.8 II as our Editors' Choice prime for everyday carry.