Voigtlander Super Wide Heliar 15mm f4.5
v Sigma 12-24mm f4.5-5.6

 

f11 Centre Frame Crops (100%)

Voigtlander 15mm at f11	Sigma 12-24mm at 15mm/f11

Still the Voigtlander shows better resolution, colour and contrast...

 

f11 Upper Left Corner (100%)

Voigtlander 15mm at f11	Sigma 12-24mm at 15mm/f11

...and still there is vignetting. As you might expect, the corners of both are sharpening up, but the improvement in the Voigtlander is subtle, and masked by the darkening, whereas the Sigma benefits from dramatic improvement as it is stopped down.

Page 3: f8 Performance <  > Page 5: f16 Performance