Lens review

Sony DT 16-50 mm f/2.8 SSM

5. Chromatic and spherical aberration

The situation of the lateral chromatic aberration looks worse – in fact it is the biggest challenge at a difficult combination of the widest angle of view and the maximum relative aperture where it exceeds a very high level of 0.18%. Such a result is still good when compared to those of the rival 16-50 mm lenses from Tokina and Pentax in which cases the aberration could rise above 0.25%. It is obvious that aberration control in a lens of this type is not easy. Although the level of it in the Sony 16-50 mm is not low it would be difficult to criticize the tested lens for it as it still fares the best of all other instruments of this type. Even 17-5x class lenses, allegedly easier to manufacture, fare alike. For example the chromatic aberration of the expensive Nikkor 17-55 mm f/2.8 reached almost 0.16% so was very similar to that of the Sony.

Defocused photos or a diode (front and back focus), posted below, show that the spherical aberration is not corrected perfectly well. In the first case we have a smooth, homogeneous light spread in a circle; in the second case you can notice a significant rim near the edge.