If you like the narrower field of view offered by a standard-angle prime, and you shoot with the Leica T, the Summilux-TL 35mm f/1.4 ASPH. ($2,395) is no doubt on your wish list. The lens captures a heck of a lot of light, and while its sharpness suffers as you move away from the center of the frame at f/1.4, it is capable of very crisp images as the aperture is narrowed. It's on the large size for a mirrorless lens, but does a fine job controlling distortion and keeping edges and corners bright. The Summilux is expensive when compared with similar lenses for other mirrorless systems, but that's a complaint you can make about just any Leica product. Devotees of the T in want of a 35mm prime that delivers perfect sharpness from edge to edge need to look at adapted, manual focus lenses. The Summilux-TL offers good performance, but it doesn't excel to the same heights as the very best of lenses.

Design
The Summilux is large for a mirrorless camera, especially for the T (Typ 701). It measures 3 by 2.8 inches (HD) and is heavy at 15.1 ounces. It's a better fit for the beefier, full-frame Leica SL. The SL will reduce its active sensor area (and image resolution) to match the 35mm when it's mounted—the lens only covers an APS-C image sensor. Videographers who use the SL will still see the appeal, as only the APS-C sensor area of its full-frame imager is used when recording 4K footage.

Build quality is excellent. The barrel is metal, with a large knurled focusing ring occupying much of its length. Like most mirrorless system lenses, manual focus is done by wire—turning the focus ring activates a motor that moves lens elements to refocus, rather than moving the elements directly—but the ring is well damped. You can feel the resistance while turning it, giving it the feel of a mechanical focus lens.

Leica offers the Summilux in black or silver, so you can choose a finish that matches your T camera. A metal lens hood is included; it's reversible for storage. You will need to remove the lens to install or remove filters; the thread is 60mm in size. There's no image stabilization, which is not a surprise, as Leica has yet to release a stabilized lens for the T.

Focus is possible as near as 1.3 feet (0.4-meter). If you're used to rangefinder lenses, that's really close—they're typically limited to 2.3 feet (0.7-meter). The Summilux doesn't enter into macro territory—at its closest focus distance it projects objects onto the image sensor at 1:9.4 life-size—but it offers a fine working distance for everyday photography. If there's any complaint to be made in terms of focus, it's that the lens is a bit slow to lock on. When tested along with the T it requires about 0.4-second to lock focus and fire. That's slower than the 0.2-second notched by the 18-56mm ($1,895.00 at Amazon) standard zoom.

Image Quality
I used Imatest to analyze test images shot with the 35mm Summilux-TL and 16-megapixel Leica T (Typ 701). At f/1.4 the lens is a little soft, scoring 1,747 lines on the standard center-weighted test. That's just a bit shy of the 1,800 lines we like to see in an image. The center third of our test image is very sharp (2,004 lines), but gives way to some softness in the mid parts and edges of the frame, both of which clock in at 1,540 lines.

Stopping down to f/2 sharpens up the entirety of the frame, with the overall score hitting 1,975 lines. Again the sharpest area is at the center (2,311 lines), with a middle third that's just slightly soft (1,724 lines) and edges that are within reason for a wide-aperture design (1,677 lines). You can easily hide some of the weakness at the edges of the frame by keeping your subject toward the center when shooting at wider f-stops.

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At f/2.8 the overall score improves to 2,169 lines, with the same pattern of sharpness—the center shows 2,500 lines, the middle third about 1,975 lines, and the edges about 1,800 lines. At f/4 the overall score hits 2,209 lines, before it peaks at f/5.6 (2,198 lines). Edges never catch up with the center, but at f/2.8 and beyond they are crisp and rife with detail.

There's a slight drop in resolution at f/8 (2,121 lines). Diffraction takes a more noticeable toll at f/11 (1,953 lines) and f/16 (1,716 lines). You can't stop down beyond f/16.

Distortion is absent, regardless of whether you shoot in Raw (DNG) or JPG format. There's a chance that the T is applying some corrections to achieve this; if it is, they're transparent when viewing Raw images in Lightroom ($9.99/Month at Adobe) . Likewise, illumination is even across the frame. Even at f/1.4 the corners only lag behind the center by a half-stop, which is well within our tolerance for Uniformity testing.

Conclusions
The Leica Summilux-TL 35mm f/1.4 ASPH. ($2,395) delivers the performance you'd expect from a wide-angle Leica lens. Its character—marked by a sharp center that gets crisper when stopped down, and edges that are clear, but never as good as the center—is similar to both the wide-angle prime lens for the T system, the Summicron-T 23mm f/2 ASPH., and the full-frame Summicron-M 35mm f/2 ASPH. for Leica's rangefinder system. It's a top performer in some respects: there's no distortion to speak of, edges are as bright as the center of the frame, even at f/1.4, and the center sharpness is excellent, especially when stopped down. But some issues keep it from getting a higher rating: the autofocus system is fairly slow, and there's something to be said for a lens that is more consistently sharp from edge to edge. If you're a T owner in want of a fast standard-angle prime with autofocus, you're faced with a Hobson's choice—there's simply no other option on the table. Luckily it's a solid one, but it comes with a premium price tag.

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