Leica Summilux-M 28mm f/1.4 ASPH review: Resolution, shading and curvilinear distortion
Resolution
The difference between edge and centre sharpness begins to close from f/4 and becomes very good at the lens’ optimal aperture of f/5.6. From f/5.6 to f/11 general resolution is excellent, though f/11 is less able for fine detail – and f/16 much less so. Wider apertures create softness around frame edges which is pleasant if anticipated and used well.
Shading
This lens demonstrates the principle that wide apertures and wide angles of view are prone to corner shading. Wide open shading is dramatic, and remains a fading feature through all aperture settings. The worst is gone by f/5.6, but is present even at f/16. Some may relish the drama of the f/1.4 shading and that it directs attention to the centre of the frame.
Curvilinear distortion
Some curvilinear distortion is to be expected with a lens this wide, and Leica isn’t entirely immune to its effects. However, the degree of distortion this lens produces is very slight, to the point that it can’t readily be detected in most pictures. What does appear can be easily corrected. It’s very good.
