Leica Summilux-M 28mm f/1.4 ASPH review: Image quality
Wide aperture and wideangle lenses are prone to image quality issues, but for the cost of this lens we’d rightly expect that Leica has worked hard to do what can be done to overcome those problems
The aberration most commonly associated with wideangles is curvilinear distortion – usually barrelling, where straight lines close to the edge of the frame bend inwards towards the corners. This is a debilitating distortion that isn’t always easy to fix convincingly, and which can take time to fix well.
Of course, fixing requires straightening the edges of the frame and then re-cropping, which loses pixels as well as some of that angle of view we just paid for.
Edge-to-edge sharpness and low curvilinear distortion make this lens suited to architecture shots
Leica has worked hard to eliminate barrelling, and I was really surprised by how well it draws. The company’s claim that this 28mm is suitable for architecture – that most technically demanding type of subject matter – seems to be true. I’m very pleased with how naturally all subjects are drawn.
Closed to f/5.6, the lens produces really sharp images that are filled with detail
We should perhaps expect some corner darkening from such a wide lens, especially at the larger apertures, and indeed vignetting is very much a part of images shot at apertures wider than f/8. At f/1.4 there is a definite bright spot in the centre of the frame that has a knock-on effect with the camera’s metering system, and until f/2.8 vignetting is severe. It looks rather good in some subjects, such as documentary photography, but is not so great for technical applications.
Wide views with shallow depth of field at f/1.4 look unusual. Note the corner shading
For all Leica’s efforts with colour there are really quite prominent purple fringes and chromatic separations in images created by this lens. High-contrast edges are worst affected, and elements close to the corners worse again. In my test images I found the tops of buildings glowing slightly at every aperture and all focus distances – something that I found was a bit disappointing, and something which also interfered with apparent sharpness in some cases.
Purple fringing is a characteristic of images taken right the way through the aperture range
The lens is sharpest when used between f/4 and f/8, with absolute resolution compromised outside the f/2.8-8 range. Having said that, it is nice enough wide open even though there is a lack of critical bite in the images. Particular photographers will avoid these extreme apertures though, and will opt for the traditional sweet spot in the middle of the range – I found f/4 with a close-ish subject could still give me some differential focus while also delivering great detail in the centre of the frame.
I used the zone focusing guides on the top of the lens on a number of occasions during the test, using a range of apertures, and found that sharpness at infinity can’t be assumed. The scale seems somewhat over-ambitious, and a degree of caution is recommended.
