Sigma 30mm f/1.4 DC DN – Test results

Resolution

Solid: 30mm centre
Dotted: 30mm corner

The MTF graphs from our Applied Imaging tests show that the 30mm f/1.4 behaves very well indeed, despite its relatively low price. It’s very sharp in the centre, with peak resolution around f/4-f/5.6. The corners aren’t quite so sharp, but this is partially due to slight curvature of field throwing them a little out of focus with our flat test chart. Overall, though, this is an excellent performance.

Shading

30mm f/1.4

Shooting at f/1.4 gives noticeable shading on Sony APS-C cameras, with the corners being about 1.2 stops darker than the centre of the frame. But stopping down to f/2.8 essentially eliminates this vignetting entirely. Micro Four Thirds users will also see less vignetting, due to the smaller size of the image sensor.

Curvilinear distortion

SMIA TV = -2.6%
30mm (uncorrected raw)

As is the way with modern lens design, the 30mm f/1.4 shows visible barrel distortion when looking at uncorrected raw files. Sigma advises Sony users to set distortion correction to Auto, which should fix this in the camera’s JPEGs. Micro Four Thirds cameras will always correct this automatically.