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Lens review

Sigma 10-20 mm f/3.5 EX DC HSM

25 September 2009
Szymon Starczewski

6. Distortion

Ultra wide angle lenses built in rectilinear projection usually don’t have much of distortion. A much higher level of this aberration is often found in universal zoom lenses of high focal length factors. The lack of straight lines curvature, with very large angles of view, has its price in distortions in the corners of the frame. We need to remember that, as distortions are not solely curvatures of straight lines.

So far, the perfect model to follow among ultra wide angle zoom lenses was the older Sigma 10-20 mm, which at the beginning, middle and end of the focal lengths range recorded distortion of values -0.88%, 1.3% and 0.9% respectively. The newest Nikon, Tamron or Tokina models didn’t come out better than this. Particularly the first one was weak, recording the results of -3.77% at its widest angle.

The new Sigma lens, sadly, reached the level of other constructions of this type and can no longer be hold up as a model for others. At 10mm focal length we recorded noticeable barrel distortion of -3.05% value. Fortunately, that’s the only bad news, as with increasing focal length the problem with this aberration is of marginal significance. At 15 mm it’s -0.34% and at 20 mm 0.30%.

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This is quite a change. The older Sigma 10-20 mm gave little distortion and the widest angle, but the cost of it was distortion of about 1% at longer focal lengths. The new construction corrects this aberration at longer focal lengths, while showing noticeable “barrel” at 10 mm.


Sigma 10-20 mm f/3.5 EX DC HSM - Distortion

Sigma 10-20 mm f/3.5 EX DC HSM - Distortion

Sigma 10-20 mm f/3.5 EX DC HSM - Distortion