At $5,150 the Leica Summilux-M 35mm f/1.4 ASPH. is one of the more expensive lenses in available for rangefinder cameras. It's the fastest 35mm that Leica makes—if you want to capture more light, the Voigtlander Nokton 35mm f/1.2 II ($999) is available, but it's a much larger, heavier lens. The Summilux is quite small and light in comparison, to the point where it's surprising that it's a 35mm f/1.4 design. While its center sharpness never disappoints, the edges do leave something to be desired at wide apertures—a disappointment, especially when you consider the price. If you don't mind a larger lens you can save some money, and get a 35mm prime that captures images with more clarity, by opting for the Zeiss Distagon T* 1,4/35 ZM , which keeps its Editors' Choice honors thanks to its performance.

Design
At just 1.8 by 2.2 inches (HD) the Summilux-M ($5,450.00 at Adorama)  is a fine example of how compact wide-angle rangefinder lenses can be. Its barrel is aluminum and it can be found in a black or silver anodized finish. It's heavy for its size at 11.3 ounces, and if you opt to use the included metal hood it's closer to 2.3 by 2.2 inches in size. That's still small when compared with the Zeiss 35mm f/1.4, which measures 2.6 by 2.5 inches without a hood. The Zeiss lens is just a little bit heavier (13.4 ounces).

The Summilux uses 46mm filters, the same size as the 50mm Summilux-M ($4,395.00 at Amazon) and the current series of f/2.4 ASPH. Summarit-M lenses. A consistent filter thread size is always a good thing if you have multiple lenses, but the screw-in lens hood makes filter changes a bit of a pain. Like the hood included with the Summarit-M 35mm f/2.4 ASPH. ($500.00 at Amazon) it must be removed to change filters. That's not quite as convenient as the built-in collapsible hood that's built into the Summilux-M 50mm.

A collapsible hood is almost expected in a premium Leica lens, but it's not practical with a wide-angle design. Even without the hood the 35mm Summilux blocks a portion of the 35mm frame as viewed through the optical finder of a digital M ($2,969.00 at Amazon) camera. With the hood the finder blockage is more noticable, even with the cut-out window at the top left corner.

This is one area where the Zeiss is worse: Its larger, longer lens barrel blocks more of the 35mm frame than the Leica alternative, leaving the bottom right corner of your image as an unknown quantity when taking a picture. I don't view this as a big deal, especially when shooting in a documentary style, but your mileage may vary. Modern digital Leicas, including the M, the M-P ($5,447.16 at Amazon) , and the Monochrom (Typ 246) ( at Amazon) , offer Live View for those times when framing is critical, and you can always opt to use an external optical finder if you're turned off by finder blockage and use a model that doesn't support Live View.

The lens has a physical aperture ring that can be set from f/1.4 through f/16 in half-stop increments. It can focus down to 0.7-meter, typical for a rangefinder lens, and has a sizable focusing tab that makes it comfortable to adjust focus with one finger. The printed depth of field scale has full-stop markings for the entire aperture range, and at longer shooting distances and narrower apertures scale focusing is certainly possible. At f/8, for example, you can set the lens so that everything from about 2 meters to infinity is in focus.

Image Quality
I used Imatest to see just how sharp the Summilux-M is when paired with the 24-megapixel M (Typ 240). At f/1.4 the lens scores 1,875 lines per picture height on a center-weighted sharpness test. That's a little bit better than the 1,800 lines we like to see at a minimum, but we expect more from a $5,000 lens. The center is quite crisp at f/1.4 (2,291 lines) but the midpart (1,591 lines) and periphery (1,518) of the frame are soft. Compare this with the Zeiss Distagon 35mm f/1.4, which scores 2,432 lines on the same center-weighted test at f/1.4 with extremely even performance right up to the edges (2,364 lines).

At f/2 the lens improves, scoring 2,206 lines on the averaged test based on a 2,814/1,775/1,634-line center/midpart/periphery breakdown. At f/2.8 the average score is better (2,683 lines). Here the center is just about as good as it gets (3,367 lines), but there is still a strong drop at the middle third (2,288 lines) and outer third (1,915 lines) of the frame. That's similar in character to what we see with the other 35mm lenses in the current Leica catalog, the Summicron-M 35mm f/2 ASPH. ($500.00 at Amazon) and Summarit-M 35mm f/2.4 ASPH.

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The edges improve more drastically at f/4. The center-weighted average is an excellent 3,008 lines, the middle third of the frame hits 2,916 lines, and the edges show 2,337 lines. At f/5.6 the lens improves to 3,187 lines, with even performance through much of the frame, and edges that lag behind just a bit at 2,758 lines.

The Summilux is at its absolute best at f/8 (3,198 lines) and the edges of the frame approach 3,000 lines. But even there it can't match the Distagon, which peaks at f/5.6 with a 3,861-line average score. Diffraction sets in for the Summilux at f/11 (2,878 lines) and is more of an issue at f/16 (2,288 lines). As is the case with the Zeiss, the Summilux shows no noticeable distortion.

Conclusions
The Leica Summilux-M 35mm f/1.4 ASPH. isn't quite the stellar performer that we were hoping for at f/1.4, but from f/2 onward it offers strong image quality with character that is similar to other Leica 35mm lenses, and at f/4 through f/8 any criticisms of image quality are akin to nitpicking. But given its price tag, and the fact that our Editors' Choice Zeiss Distagon T* 1,4/35 ZM is as good as it is and available for about 60 percent less than the Summilux, it's a tough sell from a value proposition. The real advantage of the Summilux is its size—it certainly blocks less of the viewfinder than the Zeiss, and that may be enough for some photographers. But if you're really in want of a compact 35mm that offers an unobstructed view through the finder, the Summicron-M 35mm f/2 ASPH. is a solid compromise in terms of size and maximum aperture.

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