The Leica Elmarit-M 28mm f/2.8 ASPH. ($2,195 list) is an impressively small wide-angle lens with a modest f/2.8 maximum aperture. It's compatible with Leica rangefinder cameras, although it's easy enough to use with Sony NEX and Micro Four Thirds cameras using an inexpensive adapter. It's an impressive performer, delivering sharp images at its maximum aperture, but you don't get the edge-to-edge performance that Leica shooters adore until f/4. That's still pretty reasonable for a wide-angle design, and it's even more impressive when you consider just how compact and light the lens is.

The Elmarit measures just 1.2 by 2 inches (HD) and weighs in at 6.3 ounces. The included clip-on plastic hood adds a bit of height, but not much, and its weight is impressive when you consider its all-metal construction. It can focus as close as 0.7 meter and accepts 39mm filters, the standard for smaller Leica lenses. Its aperture ranges from f/2.8 down to f/22 in half-stop clicks, and there's a tab on the focusing ring to make adjusting focus a more pleasant experience. There's no such thing as an autofocus M camera, so be prepared to focus this one yourself.

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I used Imatest to check the performance of the Elmarit when paired with the full-frame Leica M. The lens was released and designed for use on the older digital M8 camera, which featured a smaller-than-full-frame image sensor. Imatest shows that average sharpness, calculated using a center-weighted methodology, is 2,311 lines per picture height. This is in excess of the 1,800 lines that we require to call a photo sharp, but there is some softness at the extreme edges of the frame. Performance there is limited to a mere 1,347 lines, which is noticeably fuzzy upon careful examination.

Stopping down to f/4 fixes everything. The overall resolution jumps to 2,736 lines, and edges are quite impressive at 1,879 lines. At f/5.6 the overall sharpness is 3,104 lines, with edges that cross 2,700 lines, and things are just about the same at f/8. This is a wide-angle design, and it doesn't focus as close as some 28mm SLR lenses, so you won't be missing out on much bokeh by narrowing the aperture when corner-to-corner sharpness is a requirement for a shot.

There is a modest amount of barrel distortion, about 0.9 percent, which is a bit much compared to some Leica glass, but is barely relevant in field conditions. If you do notice some curvature in your images, a quick slider adjustment in Lightroom will straighten them out.

The Elmarit-M 28mm f/2.8 ASPH. is a good choice for Leica shooters who want to buy a wide-angle lens, but can't afford the Summicron-M 28mm f/2 ASPH. ($4,295). Its aperture isn't as ambitious, but its price tag is significantly lower and it's compact to boot. The lens is the widest you can use on a full-frame M without resorting to an accessory viewfinder for framing. Leica shooters who value performance over size often seek out the older, larger 28mm Elmarit on the used market, as it is said to produce sharper corners at its maximum aperture. But if you prefer the more modern look that an aspherical lens produces, and don't want to have the need for an f/2 wide-angle or the budget for the Summicron, the Elmarit-M is a solid choice. Just remember to stop it down a bit when you're going for edge-to-edge sharpness in a shot.