Canon EF70-300mm f/4-5.6L IS USM, DxOMark test results summaryFirst of all, its DxOMark score is pretty impressive for a telephoto zoom: Mounted on a 5D Mark II the results are superior or close to 10 (DxOMark Score) on the whole focal range at 5.6.This means that the global image quality will be high for every focal used, even when lighting conditions are difficult.The resolution is very homogenous in the field, however it is not very high.Distortion is very well controlled. Vignetting and chromatic aberration measurements do not show any remarkable defect.Canon EF70-300mm f/4-5.6L IS USM vs Canon