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Lens review

Sigma A 12-24 mm f/4 DG HSM

23 October 2016
Szymon Starczewski

6. Distortion

A 12-24 mm lens, even cooperating with the smaller APS-C/DX sensor, provides angles of view reaching almost 100 degrees; as you can imagine for such an instrument distortion correction is not an easy task. Still the Sigma performs admirably here. While attached to the Canon 50D at 12, 18 and 24 mm we got the following results: −0.82%, +0.27% and +0.24%. They mean that in photos provided by the smaller sensor you won’t experience any distortion-related problems, no matter what focal length you employ.

Still we were very curious about the full frame performance of the lens. Its predecessor fared quite well, showing barrel distortion of −2.67% at the widest angle but the Canon 11-24 mm didn’t exactly distinguish itself in this category; still you have to remember it faced a more difficult task as its angle of view was wider.

At 12 mm the barrel distortion level of the Sigma A 12–24 mm f/4.0 is noticeable but moderate, amounting to −2.54%. Already at 14 mm it decreases to −0.50% so becomes practically imperceptible. With the increase of the focal length the distortion changes sign and at 16 mm you deal with its pincushion variety amounting to +0.75%. At 18 mm it increases to +1.25%, and at 24 mm it reaches +1.66%.

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To sum up the Sigma fares better in this category than its predecessor and the rival Canon, taking proper care of distortion correction. With such wide angles of view such a performance should only be praised.

Canon 50D, 12 mm
Sigma A 12-24 mm f/4 DG HSM - Distortion
Canon 50D, 18 mm
Sigma A 12-24 mm f/4 DG HSM - Distortion
Canon 50D, 24 mm
Sigma A 12-24 mm f/4 DG HSM - Distortion

Canon 5D MkIII, 12 mm
Sigma A 12-24 mm f/4 DG HSM - Distortion
Canon 5D MkIII, 18 mm
Sigma A 12-24 mm f/4 DG HSM - Distortion
Canon 5D MkIII, 24 mm
Sigma A 12-24 mm f/4 DG HSM - Distortion