Canon EF 24-70mm f/2.8 USM L - Review / Test Report - Analysis
Lens Reviews - Canon EOS (APS-C)

Distortion

The level of distortion is very low for a standard zoom lens with very slight barrel distortion at 24mm and marginal pincushion distortion at 70mm. At 40mm there is no distortion at all. Really a great performance here for a zoom!

24mm:

40mm:

70mm:

The chart above has a real-world size of about 120x80cm.

Vignetting

On APS-C DSLRs vignetting is very well controlled with the lens. Wide-open vignetting does not exceed ~0.5EV which is usually not much of an issue in real life situations. One stop down the problem is basically negligible.

MTF (resolution)

Well, I guess everybody has a nemesis and mine is the Canon EF 24-70mm f/2.8 USM L. It took me 4 (f-o-u-r) samples of the lens to get a good one - please note: "good", not a "great" sample. The first three variants showed rather hefty centering defects which spoiled the results quite a bit.

This final sample exhibited a very good to excellent center resolution at wide-open aperture throughout the tested focal length range. The borders follow on a good to very good level. Stopping down lifts the center further into excellent territories and the borders improve gradually till about f/5.6 to f/8. The sweet spot of the lens is in the middle of the zoom range.

Below is a simplified summary of the formal findings. The chart shows line widths per picture height (LW/PH) which can be taken as a measure for sharpness. If you want to know more about the MTF50 figures you may check out the corresponding Imatest Explanations

Chromatic Aberrations

Lateral chromatic aberrations (CAs) can be visible at 24mm where the average width exceeds 1 pixel at the image border. At the other focal length CAs are practically negligible. All-in-all a very good characteristic for a standard zoom here.




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