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Lens review

2010-05-25
 

Sigma 8-16 mm f/4.5-5.6 DC HSM

10. Autofocus

The first question to be asked looking at the parameters of the tested Sigma is: do we really need an autofocus here? It’s easy to determine that at 8mm focal length and maximum relative aperture (f/4.5) you just have to set the distance scale at 0.8 meter to get a sharp image in the range from less than 40 cm to infinity. In such a case using up the battery for the HSM motor is perhaps rather wasteful…

At the maximum focal length the situation is just a bit worse. The focal length increases but the relative aperture changes into f/5.6. For such a combination if you set the distance scale at 2.4 meters you will get a sharp image from 1.2 meters to infinity. On stopping down the situation will only improve, after all.

Sigma decided to equip this lens with an autofocus mechanism, though and it is an ultrasonic HSM variety to boot. Its presence is obvious as the autofocus work can’t be heard at all. The focusing speed is quite good – running through the whole scale takes about 0.6-0.7 of a second.

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What about the accuracy? With such a combination of parameters you can’t expect anything less than zero misses. The depth of field is so deep that it would be difficult to miss here. There were no front or back focus tendencies either.


Sigma 8-16 mm f/4.5-5.6 DC HSM - Autofocus

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