The Leica Summicron-M 35mm f/2 ASPH. ($3,195) is a wide-angle lens for Leica and other M-mount rangefinder cameras. It covers a classic field of view when paired with a full-frame body, and is quite compact, especially when you consider its f/2 aperture. It lives up to a stellar reputation and is the go-to lens for many a Leica shooter, but it doesn't quite match the pure optical perfection of the APO-Summicron-M 50mm f/2 ASPH. ($8,795.00 at Amazon) . Still, it's a top-notch lens that won't disappoint, if you can work it into your budget. The Zeiss C Biogon T* 2,8/35 ZM ($749.00 at Amazon) is still our Editors' Choice 35mm rangefinder lens as it represents a stellar value and captures images that are very sharp, but its maximum aperture isn't as great as the Summicron.

The 35mm Summicron ($500.00 at Amazon)  measures just 1.4 by 2 inches (HD), and includes a compact hood and rubber lens cap. Weight varies based on whether you buy the lens in black or chrome. The black version is 9 ounces, but the chrome version is 12.8 ounces. The chrome lens features a brass barrel, which is heavier than the aluminum used in the black version. In addition to the extra weight, the chrome lens carries a higher price of $3,350.

The lens uses small 39mm front filters, and has a physical aperture ring that can be adjusted from f/2 down to f/16 in half-stop increments. The manual focus ring has a small finger grip for more comfortable adjustments. The Summicron can focus down to 0.7 meter, which is the limit for coupled focus for most rangefinder cameras. There's a printed depth of field scale on the barrel with full stop markings from f/2 all the way through f/16.

I used Imatest to check the sharpness and distortion characteristics of the 35mm Summicron when paired with the full-frame Leica M (Typ 240) ($2,969.00 at Amazon) . At f/2 it exceeds the 1,800 lines per picture height we use to deem an image sharp, scoring 1,907 lines. The sharpness starts to drop as you move away from the center of the frame, showing just 1,200 lines at the edges. The Zeiss Biogon T* 2/35 ZM delivers similar performance at f/2; its center-weighted score is 2,240 lines, but edges are weaker at 1,100 lines.

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Stopping down to f/2.8 improves things dramatically. The center-weighted sharpness score is 2,613 lines, and edges exceed 2,300 lines. At f/4 the lens manages 3,277 lines, and resolution peaks at 3,385 lines at f/5.6. At these narrower aperture sharpness is very even across the frame. The Zeiss Biogon 35mm f/2 also improves when stopped down, but its edges aren't tack sharp until f/4. There's basically no distortion, which is no small feat when you consider the maximum aperture and size of the lens.

The Leica Summicron-M 35mm f/2 ASPH. is small, sharp, and gathers a lot of light. Its edges aren't the best at f/2, but stopped down to f/2.8 and beyond the images that the lens captures are razor sharp from edge to edge. Like anything made by Leica, the Summicron comes with a high price tag. It's up to you if it's worth spending three times as much on it as the Zeiss Biogon T* 2/35 ZM or C Biogon T* 2,8/35, but if you do, you won't be disappointed by its construction, optics, or the look of the images you'll get with it.

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