[...] The vignetting that is typical of every optical
system is naturally more defined on a wide angle lens, particularly a high speed one like this, than on standard lenses
or those with a long focal length. At full aperture in 35mm format it is a maximum, i.e. in the corners of the image, of
around 3.4 stops, around 2 stops on Leica M8 models with their slightly smaller format . Stopping down to 5.6 visibly
reduces this light falloff – to 1.8 and 0.8 stops respectively. Stopping down further does not bring about any notable
reduction as essentially only the natural vignetting remains.