Let's do a three-stage analysis of the vignetting characteristic this time. Without any distortion and vignetting correction, the light falloff is extreme. At f/2.8, the corners are essentially black and not much brighter at f/4. The vignetting exceeds our usual scale even at f/11.The problematic corners are getting pushed off the frame with activated distortion correction but deactivated vignetting correction. The vignetting is still heavy at f/2.8 but not terrible when stopped down, considering the ultra-wide nature of the lens. With full correction enabled, the results are quite good even at f/2.8 because the light falloff is very gradual from the center to the corners. Needless to say but the signal boost comes at the cost of increased image noise in the outer image field.