posted on Mar 5, 2010 at 10:59AM
Head-2-Head Lens Review: Canon EF 16-35mm f/2.8L II USM vs. Canon EF 17-40mm f/4L USM
Chromatic AberrationBy Ted Dillard
Chromatic Aberration occurs when different wavelengths are focused at different spots on the image sensor. It shows as a colored glow along the edge of objects, and can be quite distracting.
We tested chromatic aberration on both Canon Ultra-Wide Zoom lenses at various focal lengths and aperture settings. The files were then run through Imatest, a leading application for digital image testing, for greater analysis.
At two stops down from full open, shown in the charts below, we have a much more dramatic difference. The 17-40mm f/4.0 is tracking almost perfectly along the curve; all three wavelengths are focusing on the same spot. The Canon 16-35mm f/2.8 II, on the other hand, is showing a tighter pattern stopped-down than it did at full open, but there is still some significant drifting.
Interestingly, the 16-35mm II shot at f/4.5 looks remarkably similar, if not slightly better than the 17-40mm shot at f/4.