Lens review

Sony DT 16-50 mm f/2.8 SSM

6. Distortion

Lately there has been a trend among optics constructors which I don’t like very much. They conclude that the distortion is nothing to worry about because it can be controlled by software of a camera. The constructors of Micro 4/3 lenses or many compacts are among that group so in these instruments the optics-related distortions can be really huge. The constructors of the Sony seem to go even one step forward. Not only the distortion doesn’t bother them at all but also they allowed it to turn into moustache distortion. The result is quite pitiful…

At 16 mm, averaging the distortion for the whole image, we get a very high value of –5.29%. It’s still not the end of it. This result is still lowered by the influence of the edges where the lines, bending the other way, correct it a bit. When we cut out 60-70% of the area in the frame centre and measure the distortion there we get “barrel” with a value of –6.3% - really monstrous for a rectilinear lens. It’s worth remembering here that the Tokina and the Pentax at the widest angle had deformations on the level of –4%.

What’s more the distortion doesn’t decrease so quickly. In other lenses with similar parameters it usually plummets with the lengthening of the focal length, becoming zero near 20-24 mm and then changing the sign and increasing slowly. For the Sony 16-50 mm at 24 mm focal length we still deal with noticeable barrel distortion which level nears the value of -2%. At 28 mm focal length we still see barrel of -0.87%. The distortion gets zero and changes the sign only at the end of the focal lengths range and at 50 mm it reaches a negligible value of 0.11%.

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In this category it is really difficult to praise the tested lens for anything at all.

Sony A77, 16 mm

Sony A77, 28 mm

Sony A77, 50 mm