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Lens review

Sigma 300 mm f/2.8 EX DG HSM APO

29 January 2010
Szymon Starczewski

10. Autofocus

The Sigma 2.8/300 was equipped with the HSM motor which guarantees that the focusing mechanism work will be silent and quick. We haven’t notice any record-breaking quickness but the focusing was really comfortable. The focus locks onto the subject with authority so there was little back-and-forth fine-tuning during the process.

You can have some reservations about the focusing mechanism’s accuracy, though. In the well-lit studio conditions the autofocus had 11% of misses on average which is a medium result.

It’s worth adding that this Sigma model’s test was also an experiment and a kind of test for the Sigma service centre as well. The first specimen which we got had a huge front focus. Taking into account the focal length and fastness, such a flaw simply forces you to work manually. As we wanted to omit it we decided to send our editorial EOS 20D camera to the Sigma service centre in order to calibrate the Sigma 2.8/300 lens for the test accordingly. After the calibration the lens returned without any front or back focus tendency. You can see it perfectly well in the photo below.

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Sigma 300 mm f/2.8 EX DG HSM APO - Autofocus