Lens review

Pentax smc D FA 100 mm f/2.8 Macro WR

18 March 2011
Arkadiusz Olech

10. Autofocus

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The Pentax smc D FA 100 mm f/2.8 Macro WR autofocus motor is a typical „drill” with the basic flaw of such a solution so a high level of noise. In fact we were not impressed by any category connected with automatic focusing. It is noisy and slow because when you run through the scale you have to wait about two seconds. Lack of focus limiter is very painfully felt here- we think the K-5 would deal a lot better with turning the scale if the limiter was used. What’s more, even if the right position of the autofocus is just next to the current position on the scale, the lens doesn’t make that small step in the right direction but most often it will go to one of the scale ends, bounces off it and only then finally finds the correct position. It is not a good solution for impatient people.

The accuracy of the mechanism is not perfect either. The specimen we got had a visible back focus. However, the flaw was so small that it could be corrected by the autofocus micro regulation on the K-5 menu level. After the calibration, the lens missed in about 11% of shots in studio conditions. Sometimes these focusing mistakes were very painful indeed – the differences in positions of the distance scale between one shot and the other were visible to the naked eye

Pentax smc D FA 100 mm f/2.8 Macro WR - Autofocus