The tests explained!

We test lenses to their limits in three key areas of optical performance – sharpness, colour fringing and distortion

Sharpness (high scores are better)

Figures are based on the Imatest SFRPlus chart. For an even playing field, centre, mid and edge sharpness was checked for all lenses using the same D610 body.

Fringing (low scores are better)

Colour fringing tends to be worst at the corners of the frame. To highlight how fringing affects each lens the Imatest SFRPlus chart was shot using a D610.

Distortion (close to 0 is best)

Distortions are a common trait of wide-angled lenses, especially barrel distortion. Each lens was tested at its widest focal length on the D610.