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Lens review

Sigma 120-400 mm f/4.5-5.6 APO DG OS HSM

20 October 2009
Szymon Starczewski

4. Image resolution

The picture below shows the resolution (MTF50) of the tested Sigma at the center of the frame. Measurements were conducted based on RAW files from Canon 20D.

Sigma 120-400 mm f/4.5-5.6 APO DG OS HSM - Image resolution

What conclusions arise after closely watching the results? Well, the behavior of lenses in this class is adequate to the price we have to pay for them. At the shortest focal length Sigma and Tokina 80-400 mm go neck and neck, with a slight advantage of the latter. From the focal length of 200 mm, especially in the maximum aperture range, Sigma’s advantage begins to clarify. At 300 and 400 mm Sigma dominates distinctly, although the behavior at 400 mm can only be called decent. Both independent producers are outperformed by Canon 100-400 mm IS, which comes out much better at all focal lengths. We need to remember, though, that it’s twice as expensive as Sigma and Tokina.

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Sigma 120-400 mm f/4.5-5.6 APO DG OS HSM - Image resolution

Very similar conclusions are drawn when we look at the behavior at the edge of the frame. The shortest focal lengths of Sigma and Tokina deserve praise, but the situation gets worse quickly with increasing the focal length. The range 200-400 mm is particularly week at the maximum apertures, for which the lens barely exceeds 20 lpmm. Although at 400 mm Sigma is noticeably better than Tokina, none of the lenses deserves praise here, because they don’t reach the decency boundary set at 30 lpmm at any aperture. Again, Canon is better than the competitors, showing constant behavior from one focal length to the other, distinctly exceeding 30 lpmm even at the maximum aperture. You can say a class of its own, but you need to add, class that costs.

At the end we’re presenting the clippings of our test chart obtained on JPEGs straight from the camera.

Sigma 120-400 mm f/4.5-5.6 APO DG OS HSM - Image resolution