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Lens review

Olympus Zuiko Digital ED 50-200 mm f/2.8-3.5 SWD

13 October 2009
Szymon Starczewski

10. Autofocus

The tested Olympus 50-200 mm was equipped with an ultrasonic SWD motor (Supersonic Wave Drive), so the zoom work is silent and quick. Sometimes it’s even a bit too quick. The ZD 50-200 mm autofocus mechanism appeared to act as an impatient youth who runs like the wind but with average accuracy, often being forced to make several alterations. At the longer end it often gets lost or even persistently misses the point. I witnessed such a situation myself – the lens, more than a dozen times in a row, was unable to find the right sharpness for a well-lit test table, each time missing the point and having a strong backfocus. Only a minimal change of the distance between the test table and the lens was able to help – after that, the instrument started to work properly.

In moderately lit room, where we were playing simultaneously with the E-5 plus 50-200 SWD set and Nikon D200 plus Tamron 18-270 VR set, with both lenses wide open, often the Tamron won the accuracy contest. The Olympus liked to go throughout the whole zoom range once or twice whereas it never happened to Tamron. Don’t get me wrong : I don’t want to suggest that the Tamron has a better AF system than the Olympus because it’s not the case. Although the Tamron didn’t wander around the scale, its accuracy was mediocre. The Olympus fared definitely better but wandered around too much and got lost too many times, as far as we are concerned.

Apart from the case, described above, we have no other reservations about the autofocus’s accuracy. When the Olympus finally decided where to set the sharpness, it did it well, with great precision. The number of errors reached just 1% and we haven’t observed any frontfocus or backfocus tendencies.

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Olympus Zuiko Digital ED 50-200 mm f/2.8-3.5 SWD - Autofocus