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Canon EF-S 15-85 mm f/3.5-5.6 IS USM

25 January 2010
Szymon Starczewski

5. Chromatic aberration

Chromatic aberration was also tested on RAW files from 20D and 50D. The results from 50D are slightly higher – perhaps it’s the sensor’s construction that plays its part (differently set pixels, different micro lenses). Fortunately, the differences are not big and as a matter of fact around the measuring error, which amounts to 0.005% in this case. The graphs for both cameras are presented below: the first one is the behavior on 20D, the second one on 50D. 

Canon EF-S 15-85 mm f/3.5-5.6 IS USM - Chromatic aberration

Canon EF-S 15-85 mm f/3.5-5.6 IS USM - Chromatic aberration


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We can see that aberration will trouble us the most at the difficult combination of the widest angle and maximum aperture. There it’s large. Fortunately, stopping down by 1 EV brings it down to a medium level.

In the middle of focal lengths this aberration will not bother us much. It stays around 0.06-0.09% there, so between small and medium level.

At the maximum aperture the problem increases once again, although never does it exceed the level regarded as medium. Fortunately, at 85 mm aberration is the smallest for apertures from f/5.6-f/8.0, so the ones we’ll be using the most.

The behavior of Canon 15-85 mm IS is basically identical to the one of Nikkor 16-85 mm VR. Of the three, it’s Zeiss 16-80 which performs the best, being the brightest and never exceeding the aberration level of 0.135%.


Canon EF-S 15-85 mm f/3.5-5.6 IS USM - Chromatic aberration