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Lens review

Sigma C 56 mm f/1.4 DC DN

22 December 2018
Maciej Latałło

10. Autofocus

The autofocus of the Sigma 1.4/56 DN is noiseless but not exactly quick. With the lens attached to the Sony A7R II running through the whole distance range and finding the focus takes about 1 second. That speed doesn’t depend on the direction of work.

You can also carp about the accuracy of the mechanism which performance is a bit strange. While taking sample shots I usually shoot many times the same scene at different aperture speeds. The effect I was able to reach with the tested lens depended a lot on the first photo. If the first photo was sharp, there were big chances that the majority of other shots in a given series would be sharp as well. If at the beginning or at other point the lens misfocused, it kept doing so for other 2-3 shots before the mechanism caught up something was wrong.

By the way, during the Photokina fairs we had a chance to take sample photos with the tested lens attached to the Sony A6500 and we weren’t impressed by the autofocus performance either.

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During our tests had no problems with the front focus or back focus tendencies for a change. In the photo below the subject is firmly within the depth of field and it was a shot taken in the most difficult conditions i.e. near the minimum shooting distance for which the lens is able to focus at all. A slight shift toward greater distances is nothing to worry about especially that a part of that problem might be caused by field curvature, not autofocus mistakes.

Sony A7R II, f/1.4
Sigma C 56 mm f/1.4 DC DN - Autofocus