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Lens review

Canon EF 24-70 mm f/4L IS USM

22 May 2015
Arkadiusz Olech

7. Coma, astigmatism and bokeh

Coma is imperceptible in the corners of the APS-C sensor but its influence can be noticed in the full frame corners. T he most pronounced deformations of the image of a diode are seen at the wide angle. The coma level is distinct there but still you cannot call it very high or huge. However, it is certain it contributes to the worsening of the image quality.

Canon EF 24-70 mm f/4L IS USM - Coma, astigmatism and bokeh


The lens doesn’t experience any astigmatism problems. The average difference between vertical and horizontal MTF50 values amounted to just 3.9%. It’s also worth noticing that the highest results in that category we got at 45 mm and the lowest – at 24 mm.

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The appearance of defocused light circles leaves a bit to be desired. The circles feature a distinct rim, they are a bit lighter in the centre and there is a slight trace of onion ring bokeh. In a cheap zoom lens all of those flaws would be rather acceptable, in an expensive L-series instrument they are a bit jarring to be honest.

Center, 45 mm, f/4.0 Corner APS-C, 45 mm, f/4.0 Corner FF, 45 mm, f/4.0
Canon EF 24-70 mm f/4L IS USM - Coma, astigmatism and bokeh Canon EF 24-70 mm f/4L IS USM - Coma, astigmatism and bokeh Canon EF 24-70 mm f/4L IS USM - Coma, astigmatism and bokeh
Center, 45 mm, f/5.6 Corner APS-C, 45 mm, f/5.6 Corner FF, 45 mm, f/5.6
Canon EF 24-70 mm f/4L IS USM - Coma, astigmatism and bokeh Canon EF 24-70 mm f/4L IS USM - Coma, astigmatism and bokeh Canon EF 24-70 mm f/4L IS USM - Coma, astigmatism and bokeh
Center, 45 mm, f/8.0 Corner APS-C, 45 mm, f/8.0 Corner FF, 45 mm, f/8.0
Canon EF 24-70 mm f/4L IS USM - Coma, astigmatism and bokeh Canon EF 24-70 mm f/4L IS USM - Coma, astigmatism and bokeh Canon EF 24-70 mm f/4L IS USM - Coma, astigmatism and bokeh