Lens review

Leica D Summilux 25 mm f/1.4

8. Vignetting

At the maximum relative aperture the frame corners illumination loss reaches as much as 38% ( -1.39 EV). It’s really a lot and it’s another reason why the Leica’s frame edge performance is significantly weaker than in the frame center. On stopping down to f/2.0 the vignetting level decreases only by 4%. By f/2.8 we still get 31% and by f/4.0 – as much as 27%. How weak this result is can be seen by comparing it with the achievements of the Olympus 3.5/35, which at f/3.5, so the maximum aperture for this lens, had the vignetting level of just 10%. When we stop the tested Leica down to f/5.6, the vignetting level decreases to 23%. By f/8.0 it reaches 17% and only at f/11 it becomes imperceptible.

Results of Leica in this category are worse than these of Canon 1.4/35 in which case the maximum vignetting reached 38% and stopping down to f/2.0 decreased the effect to 16%. At the f/2.8 vignetting was imperceptible in the Canon case.