LensTip.com

Lens review

Pentax HD DA 20-40 mm f/2.8-4.0 ED Limited DC WR

8 February 2014
Arkadiusz Olech

10. Autofocus

Although the lens is not equipped with any ultrasonic autofocus motor, its work is surprisingly quiet. You really have to bend close to the lens and the camera to hear a very delicate buzz during focusing.

The speed of the autofocus is hardly impressive, though. Running through the whole distance scale takes almost one second - an average result, taking into account the narrow working range of the focusing ring. At such a price point I think you have every reason to expect a really efficient and quick ultrasonic motor, which is, after all, a common feature in the rival devices, even those noticeably cheaper.

When it comes to the accuracy of the focusing mechanism it wasn’t perfect – the number of misses in studio conditions amounted to 4 %. On the other hand such a result still might be considered good or even very good at a push.


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As you can notice in the photos below, the autofocus of the Pentax 20-40 mm needed some microcalibration because of its noticeable tendency to set the focus behind the photographed object.

Pentax HD DA 20-40 mm f/2.8-4.0 ED Limited DC WR - Autofocus