Canon EF 24-70mm f/2.8L II USM Lens Review

Canon EF 24-70mm f/2.8L II USM Performance

Sharpness in the centre of the frame is very good to outstanding throughout the zoom range. At 24mm and f/2.8 sharpness is just a shade below excellent levels in the centre and very good towards the edges. Stopping the lens down to f/4 results in outstanding sharpness in the centre at this focal length, with clarity towards the edges that approaches excellent levels.

Zooming to 35mm results in an increase in sharpness in the centre at maximum aperture, although the clarity towards the edges decreases slightly. Peak sharpness across the frame is achieved at f/5.6 for this focal length, where sharpness in the centre is outstanding, and approaching very good levels towards the edges of the frame.

Finally, at 70mm, the performance of this lens holds up very well indeed. At f/2.8 sharpness in the centre remains very good, with good clarity being produced towards the edges of the frame. Peak sharpness is again achieved at f/5.6. Here the clarity in the centre is outstanding, and very good towards the edges of the frame.

Resolution at 24mm		Resolution at 35mm
Resolution at 70mm		How to read our charts The blue column represents readings from the centre of the picture frame at the various apertures and the green is from the edges. Averaging them out gives the red weighted column. The scale on the left side is an indication of actual image resolution. The taller the column, the better the lens performance. Simple. For this review, the lens was tested on a Canon EOS 5D Mark III using Imatest.

Chromatic aberrations are very well controlled, barely exceeding half a pixel width at most apertures and focal lengths. CA's just exceed half a pixel width between f/2.8 and f/11 at 24mm, rising as the lens is stopped down further. Still, this low level should cause very few issues, even in large prints and harsh crops from the edges of the frame.

Chromatic aberration at 24mm		Chromatic aberration at 35mm
Chromatic aberration at 70mm		How to read our charts Chromatic aberration is the lens' inability to focus on the sensor or film all colours of visible light at the same point. Severe chromatic aberration gives a noticeable fringing or a halo effect around sharp edges within the picture. It can be cured in software. Apochromatic lenses have special lens elements aspheric, extra-low dispersion etc. to minimize the problem, hence they usually cost more. For this review, the lens was tested on a Canon EOS 5D Mark III using Imatest.

As is typical with lenses covering this focal range, falloff of illumination towards the corners of the frame is quite pronounced at 24mm. Here the corners of the frame are 2.6 stops darker than the image centre and illumination isn't visually uniform until the lens is stopped down to f/8. Falloff is less pronounced at 70mm. Here the corners are 1.7 stops darker at f/2.8 and illumination is visually uniform by f/5.6.

Distortion is very well controlled for a lens of this type. At 24mm 3.32% barrel distortion is present, which is replaced by 0.834% pincushion distortion at 70mm. The distortion pattern is uniform across the frame, which should make applying corrections in image editing software afterwards relatively straightforward.

Though the supplied lens hood isn't very deep, resistance to flare is very high and contrast remains excellent, even when shooting into the light.

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