Resolution (f8)

f8 Centre Frame Crops (100%)

Voigtlander 15mm at f8 Sigma 12-24mm at 15mm/f8

The gap narrows: the Sigma 12-24mm has come on a bit since f5.6 whereas the Voigtlander is barely any sharper one stop down. It still comfortably retains the advantage centre frame, though.

 

f8 Upper Left Corner (100%)

Voigtlander 15mm at f8 Sigma 12-24mm at 15mm/f8

Even in the far corners (the greater length of the Sigma makes equivalent framing almost impossible) the gap is narrowing; there is still more information in the Voigtlander shot, but at f8, its strong vignetting makes it hard to tell. Vignetting one stop down is forgiveable, but at f8 it’s out of order.