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Lens review

Canon EF 17-40 mm f/4.0L USM

22 September 2007
Robert Olech

8. Vignetting

In this category the L-grade Canon also achieves a great success. For the most difficult combination of wide-open aperture and the 17 mm focal length the light fall off in the corners of the frame is only 16% (-0.49 EV). Other lenses of similar focal lengths, but designed for the APS-C detector, can only dream about such a result. In their cases the vignetting reaches as much as 40% and usually does not decrease when stopping down the lens. For Canon’s 17-40 mm f/5.6 the problem almost does not exist since the light fall off in the corners reaches only 10% and at f/8 it is 8%.

Canon EF 17-40 mm f/4.0L USM - Vignetting


The situation is identical for the 28 mm focal length. At this focal length and f/4.0 the light fall off reaches 16%, at f/5.6 it is 7% and at f/8 it is only 4%.

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At the 40 mm focal length the situation repeats itself. At the open aperture the vignetting reaches 17%, at f/5.6 it is 7% and at f/8 it is only 4%.

Canon EF 17-40 mm f/4.0L USM - Vignetting

Canon EF 17-40 mm f/4.0L USM - Vignetting