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

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

25 January 2010

Arkadiusz Olech

8. Vignetting

Vignetting is a large problem with universal zoom lenses, which start from a really wide angle. It’s worth to mention here that the light fall-off in the corners of the frame in Nikkor 16-85 mm VR reached almost 50% and in Zeiss 16-80 mm 42%. How does Canon perform in this field? You can say that similarly.

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

At the combination of 15 mm and f/3.5 the light fall-off in the corners of the frame equals 45% (-1.73 EV). At f/4.0 decreases to 38%, to reach 28% and 23% at f/5.6 and f/8.0 respectively. Further stopping down doesn’t really improve the situation.

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The whole thing improves largely at 30 mm. There, at the maximum aperture vignetting reaches 32% (-1.1 EV), to reach a non-disturbing value of 19% at f/5.6, and at f/8.0 and f/11 fall to 15% and 12% respectively.

It’s even better at 50 mm. At the maximum aperture the light fall-off in the corners of the frame equals 30% (-1.03 EV) and decreases to 14% at f/8.0 and disappears completely at f/11.

A return to slightly worse results can be seen at the maximum focal length. There, at f/5.6 vignetting amounts to 35% (-1.23 EV), falls to 19% at f/8.0 and to 13% at f/11. It becomes unnoticeable at f/16.

In this category Canon performs worse than Zeiss again, and better than Nikkor. The differences are large, but we need to remember that Zeiss gives us slightly better brightness.

It’s worth to mention one more thing here. In this category, for every aperture value we take 5-10 shots, rotating the camera after each picture by about 90 degrees. We didn’t have as many problems with any other lens, as we had with Canon, as every turn needed to be very slow and smooth. Faster moves caused unwanted zooming. It often happened that I started taking pictures at 30 mm, and after a few turns, very surprised, discovered that the focal length was e.g. 60 mm. Such slacks shouldn’t occur in a device which costs around 720 $.