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Canon EF 24-70mm f/2.8 USM L - Review / Test Report - Analysis |
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Lens Reviews -
Canon EOS (APS-C)
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Page 2 of 3
Distortions
The level of distortions is very low for a standard zoom lens with
very slight barrel distortions at 24mm and marginal pincushion distortions
at 70mm. At 40mm there're no distortions 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 in line widths per picture height (LW/PH)
which can be taken as a quantity for sharpness. If you want to know more about it 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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