LensTip.com

Lens review

Canon EF 50 mm f/1.8 STM

11 July 2015
Szymon Starczewski

10. Autofocus

The tested lens features an STM motor so the work of the focusing mechanism is very quiet. Compared to the performance of its predecessor it is indeed a nice change that will be appreciated by fans of photography and video recording as well. Still the lens can hardly be called a speed demon because running through the whole scale and confirming the focus takes about one second.

We were very happy with the accuracy of the mechanism for a change. In studio conditions it didn’t miss one single time. In order to check that performance thoroughly by f/2.8 we took 50 photos of our resolution testing chart, every time setting the focus anew. The worst result in the series was 1917 LWPH, and the best reached 2120 LWPH; the median amounted to 2034 LWPH. The maximum differences reach 10% at most so the performance of the focusing mechanism should be assessed in a very positive way.

In this category the new lens simply knocked out the older model which autofocus was not only noisy but also had noticeable repeatability problems.

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When it comes to front or back focus tendencies we didn’t notice any problems either.

50D, f/1.8
Canon EF 50 mm f/1.8 STM - Autofocus
5D Mk III, f/1.8
Canon EF 50 mm f/1.8 STM - Autofocus