LensTip.com

Lens review

Canon EF 40 mm f/2.8 STM

7 August 2012
Szymon Starczewski

10. Autofocus

The Canon EF 40 mm f/2.8 STM and the Canon EF-S 18–135 mm f/3.5–5.6 IS STM are first lenses in the Canon line-up which are equipped with an STM stepper motor. The company ensures us such a mechanism will guarantee fast and smooth automatic focusing action during recording movies. As a matter of fact you can hear only very soft electronic whirr when you focus. Unfortunately the autofocus isn’t the fastest one because running through the whole scale takes it just about one second.

Still its accuracy is beyond reproach. In studio conditions it didn’t miss one single time so it deserves a round of applause.

When attached to the Canon 50D the lens had a slight back focus tendency. It was easily corrected by the AF micro regulation mechanism, available in the camera menu. In the case of the EOS 1Ds MkIII no micro regulation was necessary because the autofocus work was seamless.

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Canon EF 40 mm f/2.8 STM - Autofocus

Canon EF 40 mm f/2.8 STM - Autofocus