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Lens review

Sigma A 40 mm f/1.4 DG HSM

10 December 2018
Maciej Lata³³o

10. Autofocus

The autofocus of the tested Sigma is noiseless but you couldn’t call it quick. Running through the whole distance scale and locking onto the subject takes about 0.8-1.0 second. For a lens which might be used as e.g. a journalistic tool it is a weak result. The speed of the mechanism didn’t depend on the camera body – the performance was similar with the lens attached to the 50D and the 5D Mark III.

When it comes to accuracy, like in the case of the A 105 mm f/1.4 DG HSM, a model we tested some time ago, we didn’t have any reservations concerning the centre autofocus point. With the side AF points the chances of blurry photos increased and the lens sometimes missfocused noticeably. Over all even 1/4–1/3 of all shots were slightly off. In the studio, on the other hand, while employing just the centre point, the number of misses never exceeded 3%.

Attached to the EOS 50D the Sigma 1.4/40 always locked on the subject without any need of microcalibration. When cooperating with the full frame EOS 5D Mark III we could notice very slight back-focus; it was eliminated by the microcalibration of the camera after setting it at −3 units.

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Canon 50D, f/1.4
Sigma A 40 mm f/1.4 DG HSM - Autofocus
Canon 5D MkIII, f/1.4
Sigma A 40 mm f/1.4 DG HSM - Autofocus