Canon EOS 7D Digital Camera Review

Chromatic Aberration

Chromatic aberration, the colored edges caused when different light wavelengths don't align perfectly, was noticeable along the outside edges, particularly at the extremes of the nearly 5x zoom range.

At the widest zoom setting, the centers are razor-sharp and the outer edges very good at the widest and middle aperture settings, with some softness creeping in with the lens fully stopped down. There's some noticeable chromatic aberration along those outer edges, again most evident at f/22.

The mid-range 90mm setting produced sharpness results similar to the widest-angle setting, with lower chromatic aberration.

Sharpness takes a hit at the full 135mm telephoto setting, though the results with the lens stopped down halfway look very good.

Distortion

We don't include distortion test results in our scoring for interchangeable-lens cameras, but we do measure it. The 28-135mm had very low distortion at the mid-range and telephoto settings, and a little over 2% barreling at the widest 28mm setting, not an unexpected result.